Wikipedia talk:WikiProject Elements/Archive 34

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Nihonium's most stable isotope half life?

I'm definitely not an expert in chemistry, so I'm going to need someone with more knowledge to help me out on this. However, I do know enough to see that I'm getting widely conflicting measurements. As given, the half-life of ²⁸⁶Nh is given as 9.5 seconds, 19.6 seconds, and 8 seconds. Which is it, exactly? exoplanetaryscience (talk) 04:46, 20 March 2018 (UTC)

@Exoplanetaryscience: The most recent value is 9.5 s from this 2017 conference paper; the 8 s value is from 2015 and the 19.6 s value from the original 2010 discovery paper (finding one atom of ²⁸⁶Nh as the granddaughter of ²⁹⁴Ts). Many of the half-lives of the heaviest nuclides are poorly known (see for example Talk:Hassium#What exactly is the half-life of Hs-270? for ²⁷⁰Hs) and the values may change again when more experiments are done. For example, while it is likely that the current assignments of atomic and mass numbers for these nuclides are correct, there is still no direct confirmation that that is the case, and there is also likely to be some undetected nuclear isomerism (see for example the case of ²⁶¹Rf as a daughter of ²⁷⁷Cn). Double sharp (talk) 06:35, 20 March 2018 (UTC)

List of chemical elements in various languages

I find this an interesting and perhaps useful idea for a list, especially given that we often cover some of these for the ancient elements with many independent etymological routes (e.g. Iron#Etymology). Double sharp (talk) 02:42, 23 March 2018 (UTC)

P.S. Note the precedent of List of numbers in various languages. Double sharp (talk) 02:43, 23 March 2018 (UTC)

Whither "Reclassifying the nonmetals"?

@DePiep, Double sharp, and Sandbh: The last piece of our discussion has rolled off to the archive, leaving behind only the index section at #Reclassifying the nonmetals.  Has apathy resulted in a consensus to do nothing? Well, at least we have a good index article to our discussions. YBG (talk) 01:18, 17 January 2018 (UTC)

No, not that consensus. I would try to write a clear proposal, but these weeks i am distracted by des vagues besognes as Brel calls inexcuses. -DePiep (talk) 08:08, 17 January 2018 (UTC)

@DePiep: Any news on a potential proposal? YBG (talk) 00:06, 6 February 2018 (UTC)

(this is taking longer than it should be, but we'll make it there)--R8R (talk) 16:43, 4 March 2018 (UTC)

I'll just pop in to point out that the predicted metallicity of Og (RSC's website calls it one; formation of Og²⁺ and Og⁴⁺ cations in OgF₂ and OgF₄ being reminiscent of Sn; the lack of utility of the GH ratio for the superheavies as it gives the oppisite answers for the metallicity of Cn and Fl to detailed calculations) suggests that we cannot treat it as a predicted nonmetal, which means that "noble gases" may have to be renamed. The current scheme would allow this to happen if we simply used polyatomic/diatomic/monatomic nonmetals, since the monatomic nonmetals are just the first six noble gases (He through Rn) but would then not include Og. Double sharp (talk) 01:31, 15 March 2018 (UTC)

This objection: you say the predicted metallicity of Og ... suggests that. A prediction that suggests? Straight to the point: do you, Double sharp, do not want "us" to make both current diatomic and polyatomic elements into "NNNM"? - DePiep (talk) 00:49, 16 March 2018 (UTC)

@DePiep: I am saying that another look at the situation is warranted. Oganesson would then be a noble gas by group and a post-transition metal or perhaps metalloid by category, creating the same problem we used to have with astatine as a halogen and metalloid (which is why we don't use groups there anymore). Whether or not this can be weaseled out of depends on whether "noble gas" is a group or a category. If it is a group, then it ends up having to disappear as a category, and then "non-noble nonmetals" becomes a bad name, while "reactive nonmetals" would necessitate "unreactive nonmetals" as rather an OR-ish synonym for what most people would loosely call "noble gases" (ignoring Og in the same way most people would ignore At). The other route is to say instead that "noble gas" is a category and so it is possible for Og to be in group 18 but not be a noble gas; only this route lets us keep on going with "reactive nonmetal / noble gas". So I'm not saying that I don't want "reactive nonmetal / noble gas"; I still support it. I am just saying that we need to take a look at how people use the term "noble gases", and that in the meantime the polyatomic/diatomic scheme offers a consistent solution that is correct until we decide to change schemes. Double sharp (talk) 02:44, 16 March 2018 (UTC)

Interesting, and mind blowing. I can follow. Sure we can handle that wrt colors, as we did with At. - DePiep (talk) 01:45, 18 March 2018 (UTC)

In Russian-language books groups are usually not named, there are families of elements instead. Conventionally: alkali metals are lithium to francium; alkali earth metals are calcium to radium; chalcogens are oxygen to tellurium (Po is ambiguous); halogens are fluorine to iodine (At is ambiguous); coin metals are copper to gold; and so on. Some of the families match some groups, but none of them form a group entirely. What's the point to include the whole group in the family at any cost? E.g., why to call Be and Mg alkali earths? They aren't alkaline at all. Droog Andrey (talk) 17:24, 16 March 2018 (UTC)

@Droog Andrey: Yes, in Japanese too Be and Mg are not considered alkaline earth metals (I agree for Be; OTOH Mg is much more alkaline than Be and comes close to Ca). The trouble is that in English they almost always are and we can't exactly change it just for Wikipedia; same for Bi, Po, and At as a pnictogen, chalcogen, and halogen respectively. These inclusions of Be and Mg as alkaline earth metals, At as a halogen, and so on are even in the IUPAC 2005 Red Book, after all. So I think this is a case where the need to follow the English literature (instead of lead in it) for the English Wikipedia means that the categorisation is already not as good as it could otherwise be. Double sharp (talk) 01:57, 17 March 2018 (UTC)

@Double sharp: OK, now we can only add hydrogen to alkali metals :-) Droog Andrey (talk) 16:51, 17 March 2018 (UTC)

@Droog Andrey: I think we can still avoid that one, since the Red Book says "The following collective names for like elements are IUPAC-approved: alkali metals (Li, Na, K, Rb, Cs, Fr), alkaline earth metals (Be, Mg, Ca, Sr, Ba, Ra), pnictogens (N, P, As, Sb, Bi), chalcogens (O, S, Se, Te, Po), halogens (F, Cl, Br, I, At), noble gases (He, Ne, Ar, Kr, Xe, Rn), lanthanoids (La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu), rare earth metals (Sc, Y and the lanthanoids) and actinoids (Ac, Th, Pa, U, Np, Pu, Am, Cm, Bk, Cf, Es, Fm, Md, No, Lr)." So we're still in the clear, since neither IUPAC nor common usage includes H as an alkali metal. (Note that this is the 2005 Red Book, so Ts had not yet been discovered and Og had not yet been externally announced; besides, neither they nor Mc and Lv had been accepted by the JWP yet.) And I might mention that not all English-language texts put hydrogen in a group in the first place; Greenwood and Earnshaw even float helium as well. ^_^

Just to be clear, I share your sentiment and would rather have "alkaline earth metal" exclude Be at least and "halogen" exclude At. The trouble is that on Wikipedia we have to reflect the status in the literature, not seek to change it. Externally, of course, things are very different. ^_^ Double sharp (talk) 16:54, 17 March 2018 (UTC)

@Double sharp: well, now we have a formal reason (while chemical reasons are obvious) to exclude Mc, Lv, Ts and Og from the corresponding families, making every family but alkali earths only a part of the corresponding group. The exceptional status of alkali earths will then give more chances for Be and Mg to be excluded sooner or later, I believe. Droog Andrey (talk) 18:00, 17 March 2018 (UTC)

To me: in English both "group" and "family" are the same (see Group (periodic table)). Confusion wrt group 1 (H is not an alkali), that's it. Translation thing? ping Droog Andrey Double sharp - DePiep (talk) 01:52, 18 March 2018 (UTC)

That's a bug I think. "Group" in our context is a vertical column of the table, a set of elements with analogous structure of valence subshells, e.g. IA group from H to Fr. "Family" is a set of elements consolidated by their naturally common properties, e.g. platinum metals (Ru, Rh, Pd, Os, Ir, Pt). Since the word "group" has a wide range of meanings, it became to be used for both things; since the most of the natural families occupy their own groups, these concepts became synonymic. But, strictly speaking, they are not the same, and superheavies from the 7th period justify this. Droog Andrey (talk) 09:55, 18 March 2018 (UTC)

Isn't all this "family" talk here about what we at enwiki call "categories"? Nice extra: in PT context, "category" is not used otherwise (unlike group and family). Already five years we have excluded At from halogens, and H is excluded from the AM's always. We note these "categories" ("families then?") by background colors in most of out PT's. However, the "Pt group" we don't call/color a category here, because it is not part of a PT-covering set. DePiep (talk) 17:06, 22 March 2018 (UTC)

@DePiep: OK, let's call it "category". So we have categories "alkali metals", "halogens", "chalcogens" and so on, and we also have groups. The category "noble gases" includes He, Ne, Ar, Kr, Xe, Rn, while the 18th group includes noble gases and oganesson, just like the 1st group includes alkali metals and hydrogen. All seems to be clear. Droog Andrey (talk) 11:42, 23 March 2018 (UTC)

@Droog Andrey:: Except for this complication: the real life chemistry word "family" would introduce all those other chemical definitions associated with "family". For example, we would have to explain/defend why we do not color the "Pt family" in our periodic table. Etcetera, into eternity. "Category" OTOH has no other such connections (but we can only use it internally). - DePiep (talk) 13:23, 23 March 2018 (UTC)

@DePiep: There are many possible families or categories of elements. The chalcogens (O-S-Se-Te-maybe Po) could be used as one; the halogens (F-Cl-Br-I-maybe At) could be used as one; the platinum group metals (Ru, Rh, Pd, Os, Ir, Pt) could be used as one. We just happened to select out of all the possible categories a set of eleven (including "unknown chemical properties") that covers all of the elements without gaps or overlaps, but that doesn't mean that those are the only categories. Double sharp (talk) 12:17, 23 March 2018 (UTC)

This applies to "families", which is a commonly used word in chemistry, and which has diffuse meaning (for example, as Droog Andrey illustrated here). However. The word "category" as used in enwiki has a more limited meaning (by our own choice). This is not to promote that meaning to the outside world at all, but it is to internally describe these sets — for lack of a better, existing word (there is none). So I'm perfectly fine that "family" has this wider varying meaning, and also there is no reason to re-define into vagueness our internal concept of "category". - DePiep (talk) 13:15, 23 March 2018 (UTC)

Group 4 element

I am going through old Good Articles with clean up tags and have come across Group 4 element. It has been tagged for expansion under the history section. I was hoping someone from this Wikiproject would take a look as i is not a topic area I have much strength in. The original GA nominator has well and truly left so it will be up to someone else. It is also the key part of a Good Topic, and that status will drop if this one is no longer a Good Article. Cheers AIRcorn (talk) 02:48, 27 March 2018 (UTC)

I think that article has other problems that due to us being rather stretched at the moment may have to wait in line for a little while to be fixed – perhaps until May has come and the winter has gone. Double sharp (talk) 03:31, 18 April 2018 (UTC)

Droog Andrey's beautiful periodic table graphic

I have upgraded this to a level-2 section, as it opens a new topic. Double sharp (talk) 14:56, 11 March 2018 (UTC)

@Droog Andrey: I love the design of your table. ^_^

Same for me. I happened to have saved the link a month ago ;-) [1]. Especially great presentation of cell-data (for example Z being near its formal position like ₈₀Hg), and cell-explanation in the pit makes a nice info spread. -DePiep (talk) 12:36, 6 March 2018 (UTC)

I presume that for the heaviest elements what we see are predictions? I am not sure that the range of oxidation states should shrink so drastically for the 6d elements; the relativistic destabilisation of the 6d orbitals would indeed favour the higher oxidation states, but most predictions I am aware of suggest that the lower oxidation states should not be unreachable (at least, I would expect Rf to have +3, Db to have +4, Sg to also have +5, Bh to also have +3 through +5, and Hs to also have +3, following the list given in The Chemistry of the Actinide and Transactinide Elements). I can agree more with Mt through Og; high oxidation states like +4 for Lv would have to be stabilised by highly electronegative ligands, and the obvious choices like O and F are knocked out because these would be class-B acceptors (like your remark about Cn not showing affinity to F).

BTW, since you publish this table, I'm curious about hearing the answer from this from someone who would be involved in this; what do you plan to do with the layout when elements beyond 118 are discovered? Elements 119 and 120 will be easy to include, but starting from 121 you'd be putting up a g-block row with not a lot of clarity on where it fits in because most of it wouldn't have been discovered yet (it'd only look complete by the time E156 rolls around, following the appearance of your Fig. 7 here). Double sharp (talk) 15:49, 5 March 2018 (UTC)

@Double sharp: thanks for your pleasant opinion :) Pure predictions start from Mt (all the numbers are gray and no one is capitalized); as for Rf-Hs, I'd better wait for more experiments. 119+ will be ignored for a while I think. Have you noticed an empirical electronegativity scale? Droog Andrey (talk) 23:03, 5 March 2018 (UTC)

@Droog Andrey: Thanks for the explanation, though I must admit that for Rf through Hs I wasn't aware of any experimental evidence for compounds other than the volatile ones in their group oxidation states; do you know where Sg^IV, Bh^VI, Hs^IV, and Hs^VI came from? And what do the greyed-out oxidation states mean for the more common elements (e.g. −1 for fluorine)? It's a bit sad about 119+ likely not showing up on the table for a while but I suppose it makes sense. (I wonder if we could put them in a sort of appendixed list somewhere until the 8th row fills up enough to justify actually drawing it in?) And yes, now that you mention it, I'm intrigued by the electronegativity scale. How does this one work? And is there a reason the whole of period 7 and the noble gases don't have values given? (If At can have a value I don't see why the essentially non-radioactive Th and U should go without.) Double sharp (talk) 23:55, 5 March 2018 (UTC)

@Droog Andrey: Incidentally I'd also like to ask you about the placement of the metalloid line (under H these two words added later Double sharp (talk) 03:09, 7 March 2018 (UTC); between Be and B; Al and Si; Ga and Ge; Sb and Te; Po and At; and after Og). Is the idea that the elements immediately next to the line should be considered metalloids, or is this a strict metal-nonmetal divide? If the latter I can understand why it doesn't go next to As and Se, although I am not quite convinced about Sb as a metal (and sometimes I wonder about Bi as a metal too), and I'm really not that convinced about Og and maybe even Ts as metals. Double sharp (talk) 02:19, 6 March 2018 (UTC)

@Double sharp: if I remember correctly, the lower oxidation states for Sg, Bh and Hs came from early predictions. Sg(V) should have some tendency to disproportionate into (IV) and (VI), I believe.

The colours of oxidation states mark the acidic (red), amphoteric (green) or basic (blue) nature of oxygen compounds. Grey colour means that the corresponding compounds either don't exist (like PtO₃) or don't exhibit acidic/basic properties (like NO).

The electronegativity scale was developed in several years comparing elements and ordering them by electronegativity. When the whole sequence was built, the numerical values were assigned: first the main reference points (2nd period with a step of 0.5), then other elements with attention to periodic trends. Noble gases have too many troubles with electronegativity; 7th period was simply ignored, although I'll maybe extend the scale in future (like Fr 0.72, Ra 0.82, Ac 1.01, Th 1.03, Pa 1.05, U 1.07, Np 1.09, Pu 1.12, Am 1.08).

The line divides metals and non-metals. Sb and Bi both have metallic conductivity, form salts with oxoacids, etc. Large atomic radius caused by relativistic destabilization of 7p leave no chance for Ts and Og to be non-metals. For me, they remind gallium and tin, respectively. Droog Andrey (talk) 12:35, 6 March 2018 (UTC)

@Droog Andrey: Well, OK, but U^V and Pu^V have similar tendencies too, and that doesn't really stop us from putting them up; so I'd think that Sg^V at least bears consideration. I wonder if the low-looking values for the 4d and 5d metals are because paying attention to periodic trends implies that the same oxidation state is considered down the group? It's well-known (or at least it should be) that elements are more electronegative in higher oxidation states (I mean, that's why Cr has 6 in red but 3 in green, and Mn has 7 in red but 3 in blue). Since Mo and W prefer 6 while Cr prefers 3, they end up looking a lot more electronegative than Cr, whereas of course if you compared +3 for each I think you'd get a trend more like the one you show (Cr 1.56, Mo 1.53, W 1.58).

Regarding metalloids: the reason I get worried about Sb and Bi is that they have a semimetallic band structure, like As and α-Sn, not a real metallic band structure. I agree that As^III is not sufficiently basic to form real isolable oxoacid salts, while Sb^III and Bi^III can manage this, but although those form via reactions with the respective oxoacids I am not quite convinced that they are really salts in the case of Sb: SbPO₄ and Sb₂(SO₄)₃ are mostly covalent (and given the small electronegativity difference between Sb and P on the Pauling scale, this isn't too surprising). Among the Bi^III halides only BiF₃ is really ionic, suggesting (along with "Bi³⁺" usually being a complex oxocation instead) that even the +3 state is a bit much for Bi to take. Nonetheless, I wholeheartedly approve of moving the metalloid line to the west of Ge; it's mostly nonmetallic, though you can force it to form an unstable sulfate, unlike Si. And I definitely prefer putting Sb and Bi in the same box to splitting them apart ^_^, and since at least Po^II (if not Po^IV) is reasonably metallic I can accept this line while simultaneously calling Sb the weakest of the metals. I'm just wondering how you'd handle the objection about Sb salts. And I accept that I may be splitting hairs about noting that As, Sb, and Bi are semimetals since, like metals, their admittedly weakened conductivity decreases with temperature. But then what are we going to do about Cn likely being a semiconductor, admittedly with a small band gap?

About Ts and Og: checking the predictions in The Chemistry of the Actinide and Transactinide Elements, I see that Ts³⁺ is compared to Au³⁺, and ionic radii suggest that it is even a bit larger. So yes, I was unduly worried about tennessine's cation-forming ability; I'd like to say I misremembered something, which is a nice way of saying I messed up. ^_^ But I'm not sure I can bring myself to call Og a metal. I mean, yes, Rn²⁺ is a thing and acts very much like Be²⁺, so Og²⁺ should be a thing too; but Og is predicted to have a structure just like Rn, and and a quick calculation of the Goldhammer-Herzfeld ratio for Og suggests nonmetallicity (it suggests metallicity for At and Ts). Double sharp (talk) 15:37, 6 March 2018 (UTC)

@Droog Andrey: P.S. This is all very much speculation at this point, but I'm curious where you'd draw the metalloid line in the "8p" row from E167 to E172. It seems to me that the onset of big relativistic effects late in the sixth period accelerates metallisation greatly (so that At and Rn already form simple cationic At⁺ and Rn²⁺), but if you look down the trend of things like Si–Ge–Sn through Cl–Br–I you see that metallisation is already happening, so that at first glance a completely metallic eighth period seems to be indicated. Yet, E172 does not seem to have a big enough polarisability to induce metallisation as the free element, and the trends for the halogen EAs and noble gas IPs seems to be doing an about-face to the extent that these values for E171 and E172 are close to those for I and Xe respectively. I admit that high IPs and EAs are encountered elsewhere in the table with the transition metals, which no one considers nonmetallic, but my discomfort with Og and E172 (eka-Og) as metals is that they are not predicted to have metallic conductivity AFAIK. I am definitely an amateur especially when it comes to these elements and so I eagerly await your explanation of why it is all right to call Og a metal like the Royal Society of Chemistry says on its page, ^_^ along with if those Sb salts are really more than "salts" (after all, As also forms compounds with similar stoichiometries, but AsPO₄ is definitely a mixed oxide and not a salt). Double sharp (talk) 03:09, 7 March 2018 (UTC)

@Double sharp: you are right that Sb and Bi are not true metals, but at least they are much closer to metals than to non-metals. Trihalides make really little sense here (AlF₃ is the only ionic as well); numerous salts of BiO⁺ are well-known. Solutions of Sb(NO₃)₃, Sb(ClO₃)₃, Sb(ClO₄)₃, Sb(MnO₄)₃ could be prepared. Copernicium could be a metalloid indeed, but I believe in 6d expansion. :) As for oganesson, I guess it will be more metallic than copernicium. E172 will be probably the only non-metal in the 8th period. Droog Andrey (talk) 22:51, 7 March 2018 (UTC)

@Droog Andrey: I'd expect Cn to be weaker than Hg as a metal, and to generally be happy sitting around in the 0 oxidation state. The ionisation energies are after all very high and the first two are actually above those of Si. ^_^ From what I understand SbO⁺ and BiO⁺ do not really exist as such and are really closer to [Sb(H₂O)₄(OH)₂]⁺ and [Bi₆(OH)₁₂]⁶⁺ respectively (though at least those are still cations, which can hardly be claimed for the other metalloids), and Ge also forms oxoacid salts (the trifluoroacetate is even quite stable). I presume the semimetallic band structure and hence rather more metal-like conductivity of Sb and Bi is what puts them over the edge. I would be comfortable calling Sb, Bi, and Po "almost metals". ^_^ (If Sn didn't have its truly metallic allotrope I'd consider putting it in the same category: Sn prefers being in the +4 oxidation state where it is not as metallic as it is in the +2 state. Sb through I and Tl through Po are happier in their two-lower oxidation state than the group one.)

I'm curious about your view of At, given its predicted metallic structure: it seems to strangely combine halogenic and metallic properties. Og as more active than Cn is reasonable, though given its predicted nonmetallic structure I wonder if one could reuse that remark and say that it strangely combines noble-gas and metallic properties. After all, forming a cation isn't everything, as not all the 4d and 5d elements actually do that. ^_^ It's only when no cation is formed and there are few metallic properties to begin with, like with Ge or As, that it starts to become an important point. Double sharp (talk) 00:17, 8 March 2018 (UTC)

@Double sharp: of course BiO⁺ isn't diatomic, that just a stoichiometry. As for metallic At and non-metallic Og: yes, I agree that could be so. Thank you for these doubts; now I'll watch the predictions intently :) Droog Andrey (talk) 00:34, 8 March 2018 (UTC)

Dividing line between metals and nonmetals

I have a little bit of time outside of my RL obligations.

The discussion between @Droog Andrey: and @Double sharp: has been remarkable. I have not had time to absorb it fully.

I did notice the references to the dividing line between metals and nonmetals, in the context of Droog Andrey's fine table. If I could be so bold I would criticise the placement of the dividing line on the basis that the criteria for distinguishing between a metal and a nonmetal are ill-defined. Good definitions normally rely on at least three attributes.

A while back, Double sharp and I had a long chat about what is a metal given there is no unambiguous definition in the literature. We more or less ended up with this:

A "metal" is a chemical element that has a lustrous appearance when freshly prepared or fractured, and one or more of the following properties:

(a) a closely packed crystalline structure^

(b) a density of at least 10 gm/cm3

(c) simple cation formation in aqueous solution#

(d) a basic oxide.

   ^Hexagonal-close packed, face-centred cubic, α-lanthanum, α-samarium, body-centred tetragonal, or body-centred cubic
   #Including aqua-cations such as [Bi(OH2)8]3+

This would make Sb a nonmetal, consistent with its nonmetallic chemistry. Actually, calling Sb a nonmetal is weird. I would call it a metalloid, as is the case in the literature generally. Like Sb, the other metalloids can be distinguished from nonmetals by their weakly acidic or amphoteric oxides. Sandbh (talk) 23:10, 9 March 2018 (UTC)

@Sandbh: I think I'm nevertheless intrigued by a "softer" approach. For one thing, a lot of elements near the boundary line are not exactly easy to put in one box or the other, and a lot of the difference comes from the oxidation states (e.g. Ge^II is more metallic than Ge^IV, though neither is generally metallic to begin with). @Droog Andrey:'s scheme seems to be based on at least the following criteria:

1. The presence of aqueous cationic chemistry;
2. The presence of a metallic band structure;
3. The formation of oxoacid salts.

Droog Andrey has agreed with my viewpoint that Sb and Bi are not true metals on these bases. Nevertheless, I think he makes a very valid point when he notes that they behave more like metals than like nonmetals. One may compare the chemistries of As with Sb and Bi to see the increasing metallic behaviour. As does not seem to form an aqueous cation, whereas "SbO⁺" is possible like "BiO⁺" (yes, I know these are not the true formulae, but what you get are still cations). Sb reacts with acids quite happily to form compounds which are stoichiometrically salts; As is much less willing to do so. Sb and Bi are semimetals, not metals, but they exhibit the normal metallic pattern of decreasing conductivity with temperature. As alloys with true metals tend to be brittle, whereas Sb and Bi alloys are not AFAIK. As is readily attacked by aqueous alkali; Sb and Bi are not even attacked by molten alkali. Both As^III and As^V are predominantly acidic; but Sb^III and Bi^III are amphoteric (although Sb^V and Bi^V are both acidic, the +5 state is the less common one for Sb and downright rare for Bi thanks to the inert pair effect). In slightly acidic solutions, Sn, Sb and Bi tend to occur as their oxides, whereas As, Se, and Te tend to occur as oxyanions.

On these bases I think it is not wrong to say that Sb is closer to Bi than to As, and that its chemistry is somewhat more metallic than nonmetallic. Given that Bi itself has some questionable characteristics as a metal and that Sb is not far behind, I think giving Sb and Bi a waiver is justifiable. In other words, maybe it is best not to look at the criteria and score them as all or nothing, but as how close they are to being fulfilled. Also, extremely good performance in one category might allow a waiver for some others; no one doubts W as a metal because of its physical properties, for example. Double sharp (talk) 03:21, 10 March 2018 (UTC)

P.S. Given that no one doubts that Be, Al, Zn, Ga, Sn, and Pb are metals, because they form cations even though they are amphoteric in all their common oxidation states, I wonder if it might not work to relax (d) a bit to simply demand indisputable amphotericity in their most common oxidation state (even if not all of them), which would allow in Sb, Bi, and Po but not Ge, As, and At from that criterion alone. In fact it almost works as a single criterion for the first 106 elements (whose aqueous chemistries are known) except for Re (and Bh and Hs are likewise expected to be exceptions), which is happiest in the +7 oxidation state where it is acidic. Simply allowing in all oxidation states doesn't solve this problem as it also admits iodine as a metal for its amphoteric +1 state. Double sharp (talk) 03:51, 10 March 2018 (UTC)

In Russian-language schoolbooks the term "metalloids" is rarely used; usually the whole set of elements is just divided into "metals" and "non-metals". So that's why my table has a single line. Astatine may go to metals in the next edition. Droog Andrey (talk) 18:59, 10 March 2018 (UTC)

I like the Russian approach. I prefer thinking of the metalloids as weak nonmetals. I tend to agree that astatine would be better shown as a post-transition metal. As such it could be expected to show appreciable nonmetallic character, as is normally the case for metals in, or in the vicinity of, the p-block. I will have more to say about Sb, later. Sandbh (talk) 05:49, 11 March 2018 (UTC)

I would agree that most of the metalloids are better classified as nonmetals than metals, but I can understand and accept antimony as an exception. As for astatine, we are to some extent running on predictions in that case, and I will summarise everything I've gathered about its chemistry from Pergamon Press' review of Cl, Br, I, and At. Astatine is predicted to have a metallic structure, and the −1 and +7 states should be rather more rare and unstable than they are for the lighter halogens; it would presumably be most at home in the relatively electropositive and Lewis acidic +1 and +3 states (with +5 perhaps a little less common because of the 6p_1/2 stabilisation). The 0 oxidation state of At behaves like that of iodine but is not easily reduced to the At⁻ anion. It is not entirely clear what the states between the well-characterised −1 (which parallels iodide), +5 (which parallels iodate), and +7 (which presumably parallels periodate) actually are and I suspect this is because in these states astatine is expected to be quite unlike iodine in having a quite cationic chemistry involving species like At⁺ and AtO⁺, which implies analogies with Sb and Bi (taking the 6p_1/2 electron pair as an extra inert pair beyond the 6s one); comparisons have also been made to Po in its extraction in these low oxidation states. Khalkin et al. (see Kugler and Keller's volume on astatine in Gmelin) have suggested the formation of what appear to be complexes of At⁺ with oxoanions such as nitrate, sulfate, bisulfate, and dichromate (they list the cation cautiously as "(AtΘ)⁺" as its structure is not well-known, but it appears to likely be an aqua complex like [At(H₂O)]⁺ or perhaps linear [At(H₂O)₂]⁺). Persulfate and Ce^IV are insufficient to oxidise At to the +5 state and appear to only reach AtO⁺; while AtO₃⁻ certainly exists, early interpretations that this was carried with IO₃⁻ were contradicted by the later finding that the At species involved was insoluble At⁺IO₃⁻, an honest-to-goodness salt of the At⁺ cation. Hypochlorite, periodate, or XeF₂ are needed to bring At to the +5 state to form the astatate anion; the latter two will also bring it to the +7 state to form the perastatate anion. I would hesitantly conclude from this that since +1 and +3 are likely to be the main oxidation states of At, not +5 and −1, and since At^I really does seem very metallic (and At^III too), this combined with the presumed metallic band structure should be enough to grant astatine, like antimony, a pass to the metals club: they seem closer to metals than to nonmetals.

Regarding the metallicity (or not) of oganesson, it seems to me that this is a peculiarity of the last main-group elements due to extreme relativistic effects making them sit uncomfortably in their allotted slots in the periodic table, almost as a premonition of the mess predicted in most of the 8th row. As a result I would like to say that periodicity as we know it might end at the 6d series with eka-gold and perhaps eka-mercury. I will discuss the predicted chemistries of elements 112 through 120 in more detail in another section, concentrating in particular on their metallicities. Double sharp (talk) 07:07, 11 March 2018 (UTC)

Yes, I agree that At(III) should be more stable that At(V). A capital red "5" in my table came from that old interpretations. It will be interesting to find some anionic species of At(III) like AtO₂^-, since the stability of HalO₂^- drastically decreases from Cl to I. Droog Andrey (talk) 11:41, 11 March 2018 (UTC)

@Droog Andrey: Kugler and Keller (1985) mention studies performed by Dreyer et al. (p. 222) that appeared to indicate that heating AtO⁺ in alkaline solution yields AtO₂⁻, but since then a new 2016 study (10.1002/chem.201504403) has shown that this is unlikely. The species "that predominates in non-complexing and non-reductive basic aqueous solutions" (as that article puts it) is actually AtO(OH)₂⁻. At about pH 1 and E over about 0.7 V (vs. NHE), AtO⁺ is the major species with At⁻ as a minor species; as pH is raised further and E is lowered, hydrolysis occurs to give AtOOH and then AtO(OH)₂⁻. Double sharp (talk) 12:08, 11 March 2018 (UTC)

@Double sharp: that's very interesting. Thanks a lot :) Droog Andrey (talk) 12:47, 11 March 2018 (UTC)

Meitnerium through oganesson

@Droog Andrey: Here are some comments from me about the last few elements as they are presented on your beautiful periodic chart. ^_^ There are ten elements listed here, so going through all of them is going to take a while. Hence I am just going to consider 109 through 111 today and deal with the rest later.

Meitnerium, darmstadtium, and roentgenium. In general, the 6d metals are expected to be quite similar to the 5d metals, though a bit larger (Rf seems to form a simple aquated cation in aqueous solution, which is basic enough for me ^_^). Droog Andrey's listed oxidation states for Mt and Ds are very reasonable, though as I've stated I'd still expect more predicted lower oxidation states for Rf through Hs (and I think we need a marker that something is predicted, so that we can continue to use the nice big numbers for Mt through Og, assuming the affinities to oxygen are still enough to make sense). It would seem reasonable to have 3 and 6 big for Mt; it seems that Ds would prefer staying in the neutral state for the most part, though we could easily treat it like Au and just have 2 big. (I'm basing these on the predictions which I collected and summarised for the superheavy element articles, e.g. meitnerium, darmstadtium, and roentgenium.) As for Rg, calculations by Keller et al. (10.1021/j100633a017) expect 3 to be the major oxidation state, like Au; 5 should indeed also be expected, thanks to the destabilisation of the 6d orbitals. I agree that −1 should not be encountered (the predicted EA falls between those of Au, which forms an anion, and those of Cu and Ag, which don't). Nevertheless, I think that 1 should be included; Keller et al. predicted that it would usually be unstable and probably only existent in the same cyanide complex that stabilises Au^I, but a 2017 study predicted that [Rg(CN₂)]⁻ should form (10.1002/qua.25393), and a 2006 study showed that [Rg(H₂O)₂]⁺ is expected to form (10.1021/ic061282s) and be a very soft metal cation. I would expect off the top of my head that the corresponding oxidation states of Mt, Ds, and Rg with Ir, Pt, and Au should get the same colours on the red/green/blue scheme, though it is possible that the slightly increased size will do more than I expect. ^_^ Double sharp (talk) 15:51, 11 March 2018 (UTC)

@Double sharp: I've just polished the electronegativity scale and updated some oxidation states for heavy elements: new version. Droog Andrey (talk) 18:20, 11 March 2018 (UTC)

@Droog Andrey: Thank you! It's wonderful to finally have an electronegativity scale that includes the transactinides. I suppose the absence of the lower oxidation states for Rf through Bh (and Hs^III) is a reflexion of the low ionisation energies expected, whereas Mt through Cn should have higher ionisation energies and favour lower oxidation states. I do wonder though if that means that Mt and Ds should have 3 and 2 also large and coloured, along with 4; it would be consistent with the importance of these lower states for Ir and Pt, and Fricke et al. indeed predicted these to be stable in aqueous solution. (Given that Mt still has lower ionisation energies than Ir, I think Pennemann et al.'s prediction of 1 as a stable oxidation state in aqueous solution for Mt is unlikely, although Ds may well indeed be happy to stay at 0.)

I'll deal with these elements later, but is there a reason why Cn is given a 3 state? I hadn't heard of that prospect and would like to add it to keep all those transactinide articles up-to-date. ^_^ I also don't see why Nh through Og should have their oxidation states uncoloured. Judging from comments across several 1970s papers by Fricke et al., I'd expect: Nh^I basic (like Tl^I and Ag^I); Fl^II amphoteric (like Pb^II); Mc^I basic (like Tl^I), Mc^III amphoteric (like Bi^III); Lv^II basic (like Po^II), Lv^IV amphoteric (like Po^IV); Ts^III amphoteric (like Au^III). I think both 1 and 3 could be large for Mc, reading his comments; I agree that by the time of Ts and Og the 5 and 6 states respectively would not be very important, though they might exist. I'll give more details about these elements later (along with the possibility of 6d expansion allowing the 3 state to exist for Nh). I hope this isn't the final 2019 version (we still have nine and a half more months before 2019 comes) and that my comments on Cn through Og (along with a few tidbits about missing oxidation states like Am^VII) aren't going to be too late! ^_-☆ Double sharp (talk) 02:06, 12 March 2018 (UTC)

@Double sharp: thanks for your comments on the oxidation states. Well, the predictions from 1970's aren't looking precise enough for me. Ds(IV) should be stabilized in octahedral complexes like [DsCl₆]^2-, while for Mt(III) there should be less stabilization because of too much negative charge which could switch d⁶ to d⁵s¹ or even d⁴s². Copernicium(III) is expected from the smooth growth of ionization energies; I've also performed some calculations by myself and found a relative stability of [CnCl₄]^- and [CnCl₅]^- (but not [CnCl₆]^2-).

I'd mostly agree with your proposal of colouring the numbers for Nh - Ts; will make a more detailed response later. Droog Andrey (talk) 13:30, 12 March 2018 (UTC)

@Droog Andrey: Very interesting to hear of your calculations! Alas I'm an amateur when it comes to this and so all I can personally do is sift through the literature. There does not seem to have been very much new since the initial breathless predictions of the 1970s, but sometimes things do come up. I'd love to hear more of your reasoned corrections to those old 1970s predictions that in some cases are still being repeated many decades later. Also, I think my exposé on Cn is ready thanks to your comments (see below). ^_^ Double sharp (talk) 14:06, 12 March 2018 (UTC)

@Double sharp: BTW, I'd also consider Rg(IV) as probably more stable state than Rg(V) (cf. [CuF₆]^2-). Droog Andrey (talk) 16:48, 12 March 2018 (UTC)

Retracting this. Calculations show disproportionation to (III) and (V). Droog Andrey (talk) 21:34, 12 March 2018 (UTC)

@Droog Andrey: I realise I neglected to mention Ts^I; given the large size of the Ts atom, I am tempted to think that it might well be basic. Certainly the amphoteric At⁺ already forms oxoanion salts like the real metals in the p-block do, and given that Po²⁺ is already basic, I am inclined to guess that a comparison of Ts^I to In^I would be on point. The fact that Ts⁺ may well be larger than Nh⁺ (larger size of Ts vs. Nh and lessened stabilisation of the oxidation state), together with the lower electronegativity of Ts compared to Nh, suggests to me that Ts⁺ could be basic like Nh⁺, while Ts³⁺ could remain amphoteric like AtO⁺ and Au³⁺. Double sharp (talk) 07:03, 13 March 2018 (UTC)

I'll note incidentally that the greater basicity of Rf through Sg than Hf through W is corroborated by experiments: Rf⁴⁺ seems to exist as a non-hydrolysed species, and hydrolysis of Sg^VI only proceeds as far as cationic complexes such as [Sg(OH)₄(H₂O)₂]²⁺ where W^VI proceeds to neutral WO₂(OH)₂. Only by Bh (incidentally the start or 6d_5/2 filling) does the change lessen, as Bh cannot handle a +7 oxidation state the way Np can. Double sharp (talk) 11:03, 14 March 2018 (UTC)

Calculations (10.1063/1.476993) indicate that Rg should be a good homologue of Au, save perhaps having a slightly greater tendency towards the higher oxidation states (+5 should be more important for Rg than for Au, at least when it comes to fluoride complexes). Double sharp (talk) 14:22, 17 March 2018 (UTC)

@Double sharp: my calculations also support higher stability of [RgF₆]^-. Droog Andrey (talk) 17:45, 17 March 2018 (UTC)

@Droog Andrey: Thanks for the predictions! Are there any prospects for oxidation state VII (raised as a question by 10.1063/1.473437)? Double sharp (talk) 06:10, 18 March 2018 (UTC)

@Double sharp: nope. Too much for Rg :) Droog Andrey (talk) 10:16, 18 March 2018 (UTC)

Copernicium. The prospect of oxidation states of Cn beyond +2 is, as Droog Andrey mentions, strongly suggested by the relatively smooth increase in ionisation energies. For example, Ds and Rg also seem to have a fairly smooth increase in ionisation energies (in eV, Ds: 9.9, 19.6, 31.4, 41, 53; Rg: 10.7, 21.5, 31.9, 42, 55; Cn: 11.4, 21.1, 32.8, 44, 57). I can't find enough data for Pt and Au at molar ionisation energies of the elements, but I would not be surprised if they show the same trend at a smaller scale, while Hg has a clear jump between the second and third ionisation energies. The standard electrode potentials given by Seaborg and Keller (1986) for elements 110, 111, and 112 are: Ds²⁺/Ds +1.7 V (viz. Pt²⁺/Pt +1.2 V); Rg³⁺/Rg +1.9 V (viz. Au³⁺/Au +1.52 V); and Cn²⁺/Cn +2.1 V (viz. Hg²⁺/Hg +0.85 V). I would therefore suspect that Cn is a transition element in the sense that its d-electrons are likely to be valence electrons; like Pt and Au (not to mention Ds and Rg), it should be very noble and difficult to oxidise from the metal, but should show multiple oxidation states once it is oxidised. Some small calculated steps in the direction of Hg^III and Hg^IV have been made (see 10.1021/ic702384y for the +3 oxidation state of the group 12 metals); anionic d⁹ complexes are quite common (e.g. Cu^II), and increased relativistic effects for Cn over Hg suggest its possibility in Cn^III (not to mention Cn^IV which has been expected since the earliest predictions). It nevertheless seems likely, given equivocal results about CnF₄, that these higher oxidation states of copernicium would be preferably found in anionic complexes, and given that Cn would be strongly on the class-B side complexes with Cl, Br, and perhaps I may be preferred to those with F (which, if existent, would likely suffer strong hydrolysis in aqueous solutions). The chemistry of Cn thus would seem to parallel that of Hg in the +2 oxidation state (10.1021/jp050736o and others suggest that when Cn does something that has a direct analogue with Hg, it matches fairly well) but be closer to its row-neighbours Ds and Rg in the +3 and +4 oxidation states. We already have some direct experimental evidence for the former in the ready formation of CnSe. (Hopefully this is not too wrong-headed, but since it agrees with you and you've done the calculations I'm quite relieved! ^_^) Double sharp (talk) 14:06, 12 March 2018 (UTC)

10.1063/1.473437 compares CnF₄ with PtF₄ (they are isoelectronic if you ignore the likely inert 7s electrons on copernicium). Double sharp (talk) 14:25, 17 March 2018 (UTC)

@Double sharp: they are not isoelectronic at all. 7s is totally consumed for Cn(IV).

BTW, Cn(III) seems to be more stable than Cn(IV):

CnCl₃^- + ¹/₂Cl₂ = CnCl₄^- - 5 kJ/mol

CnCl₄^- + ¹/₂Cl₂ = CnCl₅^- - 44 kJ/mol

The values are given for gas phase. CnCl₃^- is T-shaped, CnCl₄^- is a rhomb and CnCl₅^- is a square pyramid. Droog Andrey (talk) 17:45, 17 March 2018 (UTC)

@Droog Andrey: Yes, they're not, though the paper seems to be saying they are: "We also like to mention that if we consider the 6s²-electrons as "inert" [CnCl₄] is isoelectronic to PtCl₄, a well-known compound". (I meant the chlorides but accidentally wrote the fluorides, but I think that doesn't matter.) Admittedly I cannot find a way of counting electrons that makes this sensible, unless Cn^IV ignores the 7s electrons completely and simply takes all four from the 6d shell. Thanks for the interesting calculation! Double sharp (talk) 03:31, 18 March 2018 (UTC)

I'm on a bit of a roll here, so let's have another:

Nihonium. Seth et al. (10.1063/1.480168) have investigated the possible participation of the 6d electrons in bonding. The 2nd IP of Nh (23.94 eV) is expected to be the highest in group 13 apart from that of B (25.15 eV), and their conclusion was that the +3 and +5 oxidation states of Nh that would have us involve the 6d electrons should be highly unstable. Nonetheless, their calculations were focused on neutral compounds, such as NhH₃, NhX₃, NhH₅, and NhF₅ (in which there is appreciable 6d involvement in the bonding, but H₂ or X₂ molecules are readily eliminated), and they have noted that anionic complexes such as NhF₄⁻ and perhaps NhF₆⁻ may provide the only hope for the stabilisation of such oxidation states, (I suspect it might well be a forlorn hope, as while 6d is higher up than 7s it's not really higher up by that much, and the gap between the 1st and 2nd IPs of Nh is similar to that between the 2nd and 3rd IPs of Hg.) Thus I would think that early speculations for volatile hexafluorides of Nh and Fl can be written off as non-events and the only oxidation state of Nh that is likely to occur is +1. Incidentally Fricke and Waber in their 1971 Actinides Reviews paper outright says that Nh₂O would be a basic oxide: "The [Nh⁺] ion may, however, form only a slightly soluble oxide whose solution will be alkaline;(considerable polymerization could be anticipated) and this solution will readily absorb carbon dioxide from the air. Like argentous and aurous oxides, the oxide of [Nh⁺] may be soluble in ammonia." The anticipated reduction potential for the Nh⁺/Nh couple is +0.6 V (compare Tl⁺/Tl −0.34 V, Ag⁺/Ag +0.8 V, and Cu⁺/Cu +0.52 V), suggesting again that Bh through Lv are all quite noble metals. Nh⁺ can probably best be compared with Ag⁺ and Tl⁺, which have similar sizes. (I'll have to rewrite the Nh article slightly to include these results against higher oxidation states than +1.) Double sharp (talk) 14:45, 12 March 2018 (UTC)

@Double sharp: actually the second IP for Nh is larger than for Cs. Of course, 6d orbitals in Nh are more diffuse than 5p in Cs, and calculations suggest a metastable phase Cs[CsF₈] (my OR), so some stabilization might occur for Nh, but I'd still concern higher oxidation states of Nh as exotic ones. Droog Andrey (talk) 16:48, 12 March 2018 (UTC)

@Droog Andrey: Good point! There are predictions that Cs may use its 5p electrons as valence electrons under pressure (10.1038/nchem.1754), and Nh might do the same, but that is certainly not the normal chemistry of either element. Double sharp (talk) 01:25, 13 March 2018 (UTC)

P.S. The predicted crystal ionic radius of Nh⁺ is 148 pm; compare Tl⁺ 164 pm, Ag⁺ 129 pm, K⁺ 152 pm, and Rb⁺ 166 pm. The first two are likely to be better comparisons as the 7p elements should have strong class-B character. This suggests that Nh⁺ mostly follows Tl⁺ in chemistry but should have some traits reminiscent of Ag⁺, such as easier complexation as Keller et al. (1970) predict. Double sharp (talk) 03:12, 13 March 2018 (UTC)

Flerovium. Similarly to nihonium, Fl should be a very noble metal and it seems likely that coaxing it even to the +2 state will be difficult (albeit not as hard as for Cn; the predicted reduction potentials are +2.1 V for the Cn²⁺/Cn couple but only +0.9 V for the Fl²⁺/Fl couple, which should be compared to Pb²⁺/Pb −0.13 V, Cd²⁺/Cd −0.40 V, and Hg²⁺/Hg +0.85 V). It is probably reasonable to compare Fl²⁺ not only with its lighter congener Pb²⁺ but also with the similarly-sized Cd²⁺ and Hg²⁺; the tendency should be towards more complex formation, with Cl, Br, and I more so than F (if F complexes do form, they should again be readily hydrolysed). Fl^II is expected to form oxyanions, similarly to Pb^II. The similarities to Hg with the closed-shell configuration do make me wonder if Fl²⁺ would swing enough towards basicity; Fl may well have an even lower boiling point than Cn and it should be compact and not very reactive (10.1021/jp050736o) but not totally inert. Who knows, it might be better coloured blue instead of green after all! I'd be curious to hear your take on this. Double sharp (talk) 14:56, 12 March 2018 (UTC)

I changed my mind back again: Fl^II is probably better coloured green (amphoteric). Keller et al. predict the formation of flerovites analogues to plumbites, which would presumably occur in strongly basic solutions, suggesting that FlO is amphoteric. Note that CdO and HgO, though predominantly basic oxides, can with difficulty be made to show amphoteric properties, so that if FlO is intermediate between these and PbO amphotericity is likely. Note that the expected crystal ionic radius of Fl²⁺ of about 131 pm is only just below that of Pb²⁺ at 133 pm and appreciably higher than those of Cd²⁺ (109 pm) and Hg²⁺ (116 pm). It seems likely that Nh⁺ and Fl²⁺ behave for the most part like Tl⁺ and Pb²⁺, as expected, except for some analogies to Ag⁺, Cd²⁺, and Hg²⁺ that can be drawn on the side. Double sharp (talk) 03:12, 13 March 2018 (UTC)

Moscovium. Calculations by Keller et al. (1974; quoted in various sources, like Fricke's papers and the chapter in The Chemistry of the Actinide and Transactinide elements) suggest that Mc⁺ and Mc³⁺ are closest to Tl⁺ and Bi³⁺ in the periodic system (the former being suggested by similar ionic radii and the analogy of Hg with the quasi-closed shell to Fl). That would make Mc⁺ likely basic and Mc³⁺ likely amphoteric (and it would probably be more like McO⁺ stoichiometrically, using Bi as a model; indeed Keller et al. expect hydrolysed salts like McOCl and McOBr). The Mc⁺/Mc couple is expected to have electrode potential +1.5 V (compare Tl⁺/Tl −0.34 V); no values for Mc³⁺ are listed, but they might well be more positive than those of the couples Tl³⁺/Tl (+0.72 V) and Bi³⁺/Bi (+0.31 V). Given the analogies to Tl⁺ and Tl³⁺ I am inclined to agree that Mc^I would be the favoured oxidation state, but Mc^III would likely still be important and may well be the more important state in organomoscovium compounds. It thus seems that relativistic effects have created a "knight's move" relationship linking Cn, Nh, Fl, and Mc not only to Hg, Tl, Pb, and Bi, but also to Pt, Ag, Cd and Hg, and Tl respectively. I must confess that I do not understand the comment of Keller et al. that "Bismuth shows slight amphoteric character and thallium shows essentially none; so [Mc³⁺] is not expected to be amphoteric to any degree."; if we expected Mc³⁺ to be intermediate between them, one would expect it to similarly be slightly amphoteric, and Tl₂O₃ is certainly an amphoteric (though leaning basic) oxide. Nevertheless, if we instead suppose that periodicity holds passing from Bi³⁺ to Mc³⁺, the gross increase in size of the Mc atom thanks to the 7p_3/2 destabilisation seems to make it about as large as the Lr atom from Droog Andrey's chart. This might well suggest that Keller et al. are correct and that Mc⁺ and Mc³⁺ are both, for the most part, basic! Double sharp (talk) 15:39, 12 March 2018 (UTC)

The predicted effective ionic radius of Mc⁺ is 150 pm (compare Tl⁺ 150 pm and Nh⁺ predicted 140 pm), so that Mc⁺ and Tl⁺ should be very much analogous. The predicted effective ionic radius of Mc³⁺ is 100 pm (compare Bi³⁺ 103 pm, Tl³⁺ 88.5 pm). The large shrinkage that this implies stabilisation of the +1 and +3 oxidation states of Mc due to solvation and lattice energy. Now Bi₂O₃ leans towards the basic side of amphoteric, while Tl₂O₃ is amphoteric; if Mc₂O₃ is intermediate, though leaning towards the Bi side, it should likewise be amphoteric but leaning towards the basic side. (So once again I've changed my mind back to my original assignments.) Mc⁺ should have a considerable cluster chemistry (10.1016/0020-1650(73)80140-0). Double sharp (talk) 03:22, 13 March 2018 (UTC)

P.S. There seems to be a good deal of confusion about the sign of the electrode potential for Mc⁺/Mc: Hoffmann et al., following Keller et al., give a reactive Mc with potential −1.5 V, while Fricke et al. give +1.5 V. In light of Lv having +0.1 V for Lv²⁺/Lv it is possible that reactive Mc is more likely. Double sharp (talk) 08:25, 17 March 2018 (UTC)

Livermorium. Element 116 is the least-studied member of the 7p series. It seems likely (10.1038/265715a0, Grant and Pyper 1977) that the main oxidation state will be +2, and that Lv^II should form with an ease approaching that of the alkaline earth metal cations and hence be quite basic. If the unqualified reduction potential value of +0.1 V given in The Chemistry of the Actinide and Transactinide Elements is assigned to the Lv²⁺/Lv couple, then one would similarly expect it to be somewhat less noble than Po (Po²⁺/Po 0.6 V), corroborating this idea (the Lv dihalides should be ionic; while the heavier volatile Po tetrahalides are covalent compounds as gases, the corresponding Lv compounds should not be stable). Lv^IV should be reachable with strongly electronegative ligands, perhaps in mixed oxides; it has a similar radius to Ce^III. The large atomic size seems to exceed that of Rf and almost match that of Pu, judging from Droog Andrey's chart again, suggesting to me that Lv^IV might still be basic. This may be corroborated by Grant and Pyper's comment that a long-lived Lv isotope could reasonably be searched for in monazite as a quadrivalent phosphate(!) or mixed oxide. Double sharp (talk) 16:01, 12 March 2018 (UTC)

Again from Grant and Pyper, the predicted ionic radii are Lv²⁺ 135 pm (compare Mg²⁺ 68 pm; the closest seems to be Ba²⁺); Lv⁴⁺ 101 pm (compare Po⁴⁺ 97 pm). The II state would hence surely be basic. Lv⁴⁺ seems to be even larger than Th⁴⁺. The little problem is that it seems likely to be very difficult to get Lv into the +4 state in the first place; normally these higher oxidation states are not really ionic but covalent, like PoCl₄. It is worth noting that PoO₂ is mostly basic and shows its amphoteric side for the most part in concentrated aqueous alkali, like Bi₂O₃; given the usual that of high oxidation states are usually stabilised by oxyanion formation, it seems likely that the little Lv^IV chemistry we see would have LvO₂ less stable than LvO₃²⁻, for instance. Note that the gap between the 2nd and 3rd ionisation energies of Lv are close to that of Hg, although the ionisation energies are lower. Double sharp (talk) 03:36, 13 March 2018 (UTC)

Tennessine. If astatine already had doubts about whether it is a metal or a halogen (I'm inclined to say that it's far more of a metal than a halogen, especially since it's a metal in its common oxidation states), tennessine is a shoo-in for metallicity. The ionisation energies of Ts are a bit lower than those of Au, after all. The EA of Ts is expected to be close to that of Ag (10.1021/jp107411s suggests 1.281 eV), so it is difficult to even expect the −1 oxidation state to appear. In fact, it seems likely that Ts is in fact less electronegative than Nh, which should be stuck in the +1 oxidation state for the most part. An extrapolation from At would seem to suggest I and III as the main oxidation states. The first 5 ionisation energies of Ts are given at 10.1021/jp107411s (which I should add): in eV, they are 7.310, 14.877, 22.407, 41.591, and 52.614. There is a gap between the 3rd and 4th ionisation energies; the values for At are 9.040, 17.473, 26.247, 39.334, and 50.071, where the gap is there but not that large. Given that Lv^IV is expected to be stabilised only by the most electronegative ligands, and that the gap between the 2nd and 3rd ionisation energies of Lv is less than that between the 3rd and 4th ionisation energies of Ts, I would think that Ts^V should not be expected, especially given the difficulty of getting At to the +5 oxidation state in the first place. (Of course, we should note that such compounds are not going to be ionic.) Fricke et al. draw analogies between the ion-exchange behaviour of Ts³⁺ and Au³⁺ in halide media. Given the likely importance of the +1 and +3 oxidation states I would be tempted to draw analogies to In as well as At; Ts⁺ might well be basic, as already the linear At(H₂O)₂⁺ cation looks like the typical 2-coordination of Ag⁺. It may well be larger than the basic Nh⁺, and we already know that Ts should be less electronegative than Nh. Double sharp (talk) 06:58, 13 March 2018 (UTC)

Oganesson. I have refrained from suggesting colours for this one so far because its very status of metal or nonmetal still needs to be sorted out. Judging by the likely nonexistence of Ts^V, Og^VI should also be ruled out, and hence its chemistry is even further limited to low oxidation states in which it likely has more cationic character. For example, RnF₂ is rather salt-like and OgF₂ is likely to do the same. In halogen fluoride solutions Rn is usually present as Rn²⁺ or as radon fluoride complexes and it seems likely that Og will do the same, which would be reminiscent of Be²⁺. (Of course, since there don't seem to be oxides of Xe^II and Rn^II, those numbers can stay gray; KrF₂, XeF₂, and RnF₂ are reduced by water to form the noble gas, HF, and oxygen. Nevertheless, given that XeO₂ is now known as a hydrolysis product of XeF₄, xenon should probably get 4 in red together with 6 and 8.)

In order to touch on the metallicity of Og, we have to back up and look at the incipient metallicity of Rn: in fact, Rn has already been called a metalloid thanks to its cationic chemistry (10.1080/00268979100102951). What is interesting is the anomalously high metallicity of At and Rn, together with their tendency to form ionic rather than covalent fluorides, and their unwillingness to be oxidised past their cationic oxidation states (At^III and Rn^II). Stein (1983, 10.1524/ract.1983.32.13.163) writes that RnF₄ would be less stable than RnF₂: not even the most impressive fluorinating agents like ClF₅ and O₂F₂ appear to oxidise Rn past the +2 state. There have nevertheless been reports (10.1016/S0898-8838(08)60149-X) from tracer experiments that heating a mixture of Rn, Xe, F₂, BrF₅, and either NaF or NiF₂ yields a higher fluoride of radon (either RnF₄ and RnF₆) that hydrolyses in aqueous solution to give RnO₃ (whence the red 6 on Droog Andrey's table); this interpretation has nevertheless been disputed (10.1021/ic00190a051). It seems that the problem with Rn is that it is kinetically hindered at the divalent state (10.1016/0020-1650(75)80185-1) because of the ionicity of RnF₂ and the high positive charge on Rn in RnF⁺ (and At may well have the same problem with its fluorides). This would explain the success of tracer-scale experiments alone in producing higher radon fluorides where the ionic lattice does not form; having Xe in the mixture, diluting the Rn in a much larger amount of Xe, then allows its more xenon-like character in its higher oxidation states to show. Based on the existence of At^VII, the strongest oxidising agents may then be able to produce Rn^VIII (10.1007/978-1-4020-9975-5_2).

What then does this imply for the metallicity and oxidation states of Og? Well, OgF₂ should certainly behave like a salt. But it seems likely (10.1021/jp983665k) that due to the immense polarisability of Og even OgF₄ is quite salt-like, creating not only an Og²⁺ but also an Og⁴⁺ cation that would be truly remarkable for a nonmetal; this is rather like the chemistry of Sn indeed (the ionisation energies are also quite close). In general, because of the contraction and stabilisation of the 7s and 7p_1/2 shell, the operative oxidation states of Ts and Og must be considered as +1 and +3 for Ts and +2 and +4 for Og respectively; they thus appear to take a position in the table analogous to that of indium and tin, as they are maximally trivalent and tetravalent elements with some chemistry in the two-lower oxidation state, and indeed this comparison of Og to group 14 (along with Fl to group 18) is not new (10.1021/jp982735k). I admit that this information is not enough based on our criteria, but the presence of what seem like Og²⁺ and Og⁴⁺ cations is quite convincing to me. Against this would be that bulk solid Og is still expected to have the fcc structure of solid Xe and Rn, but interestingly the predicted cohesive energy of Og (~500 meV/atom) exceeds that of Cn (~400 meV/atom) and Fl (~200 meV/atom) and approaches that of Hg (670 meV/atom). I think I'm persuaded that it may be more useful to call Og a metal than a nonmetal, albeit one with a non-conducting structure in the bulk state like Cn (and if we are comparing Og to Sn, remember that α-Sn doesn't have a metallic band structure either). Whether or not we should colour in the numbers depends on oxide formation, but I would expect something similar to Sn (both +2 and +4 may well be amphoteric); what do you think? Double sharp (talk) 14:14, 13 March 2018 (UTC)

The quote about the salt-like Og fluorides, updating the symbol "(118)" throughout: "The local Og atom in OgF₂ and OgF₄ will loose electron densities due to highly electronegative fluorines and become an open-shell ion. The HF natural population charges for Og of OgF₂ and OgF₄ are 1.44 and 2.79, respectively. The spin-orbit effects may be more significant for open-shell cationic Og than for the closed-shell neutral one." Admittedly cationic Og⁴⁺ would also have the closed-shell configuration of Fl, so perhaps this is not a true Og⁴⁺ cation, even if Og²⁺ is likely, though the extreme polarisability of oganesson light help things somewhat. Og then might be more like germanium than tin; amphoteric in the II state, in which it is more metallic, but very much more acidic in the IV state. Note that Rn²⁺ does not exist in aqueous solution, though I am not sure if Og²⁺ would be. The upshot is that I am still flip-flopping over whether the best model for oganesson in group 14 is germanium or tin, especially given its nonmetallic structure, albeit with a stronger cohesive energy than the closed-shell metals copernicium and flerovium (which nevertheless seem to act like normal metals once you succeed in getting them out of the 0 oxidation state). In the absence of information on further predicted oganesson chemistry I worry that we may not be able to answer the question of whether oganesson is closer to metals or nonmetals. Even the predicted structure may not give enough information, given the precedents of bismuth and copernicium. Double sharp (talk) 03:24, 14 March 2018 (UTC)

At User talk:Sandbh#Goldhammer-Herzfeld ratio of oganesson, I wrote the following comment:

An interesting question is to look at copernicium and flerovium as well, as they also have closed-shell structures. Cn has an ideal-like hcp structure and a density of around 23.7 g/cm³ (about what you would expect calculating from Cd and correcting for the non-ideal crystal structure it has). Thus its molar volume is about 285/23.7 = 12.0 g/mol (compare Hg 14.82 g/mol) and its polarisability is close to that of Hg. This implies that Cn has an even higher Goldhammer-Herzfeld ratio than Hg (which is already strongly metallic), and yet calculations predict it to be a semiconductor. Flerovium has a hcp structure and a density of around 14 g/cm³; this gives a molar volume of about 289/14 = 20.6 g/mol (compare Pb 18.3 g/mol) and its polarisability is about two-thirds that of Pb. That would seem to be enough to push down its ratio from the approximately 1.25 on Pb (eyeballing the graph) to about 0.75 for Fl. And yet, all levels of theory predict that Fl is at least a semimetal (like Bi) and is probably a metal in its band structure (10.1103/PhysRevB.82.155116). I am willing to conclude therefore that the GH ratio is not giving useful results in the 7th period where relativistic effects rule. Unfortunately the one article I can find about the solid state of Og simply extrapolates the fcc structure from the lighter Rn and thus I think that the best answer for Og that can be given now is "we simply don't know".

As a result, given that the GH ratio fails spectacularly on Cn and Fl (from relativistic calculations), I am not confident that it will give the right answer for Og either. Double sharp (talk) 15:21, 14 March 2018 (UTC)

Elements 119 and 120. I realise that these are probably not going to go on your periodic table, even when they do get discovered, but these seem worth talking about. Chemically, they are obviously going to be strong metals with 1 and 2 marked in blue respectively: the ionisation potentials are predicted as about 2.7 V and 3.0 V respectively for the 119⁺/119 and the 120²⁺/120 couples (10.1088/0031-8949/10/A/001). The main interesting question here is if the 7p_3/2 electrons might also be ionisable to give oxidation states higher than 1 and 2 respectively. For E119, the difference between the 1st and 2nd ionisation energies is similar to that of Cu, Ag, and Mc, suggesting that element 119 may have some group IB-like properties in the same way that element 165 may have some group IA-like properties. I think we can therefore seriously expect a minor +3 oxidation state as predicted by Hoffmann et al. (10.1007/1-4020-3598-5_14), which like the +3 oxidation states of those three elements would probably show amphoteric behaviour (which would be consistent with colouring Og²⁺ in as amphoteric, continuing the trend from a perhaps basic Ts⁺). Annoyingly I have not found values for 3rd and higher ionisation potentials of E120, but Hoffmann et al. likewise predict a minor +4 oxidation state for it. Nonetheless reading the graph Fricke gives of the predicted DFS energy eigenvalues predict the energy gap between 8s_1/2 and 7p_3/2 for E120 to be more than that between 7p_3/2 and 7p_1/2 for Lv as the 7p_3/2 electrons rapidly retreat into the core, so that while E119 might show higher oxidation states I am doubtful that E120 would. (Similar reading of his figures seem to suggest the possibility of a +3 state for E165 but not a +4 state for E166). Double sharp (talk) 14:53, 13 March 2018 (UTC) @Droog Andrey: I've finished this series, with cautious conclusions of: Nh^I basic; Fl^II amphoteric; Mc^I basic (capital), Mc^III amphoteric; Lv^II basic (capital), Lv^IV amphoteric; Ts^I basic, Ts^III amphoteric (capital); Og^II and Og^IV amphoteric if they form oxides (which I'm not sure about); Uue^I basic (capital), Uue^III amphoteric; Ubn^II basic. Also, I think I'm rather convinced about Og being closer to metals than nonmetals on account of its greater activity than Cn or Fl and its analogies to the group 14 elements like Sn. In case I am saying anything wrong from my misunderstanding of the sources or from them being too old please do correct me. ^_^ Double sharp (talk) 14:53, 13 March 2018 (UTC)

@Double sharp: great thank you for such a detailed review. I'd mostly agree on the colourings, maybe doubting a little about the basicity of Nh and the oxygen affinity of Ts(I). Oganesson should be definitely a metal I think: in periods 4-6 the rate is two groups/period (Ga-Sb-At line), and the np_3/2-(n+1)s gap shrinking is relativistically accelerated, so I'll be very surprised if Og appear at least as non-metallic as α-Sn. Droog Andrey (talk) 19:40, 14 March 2018 (UTC)

@Droog Andrey: Thank you for reading through all of it and your agreement! Could we perhaps expect those numbers to be coloured in for a revised edition? ^_^ We're still early for 2019, after all.

I agree that Nh⁺ should have some amphoteric tendencies (which would explain its expected polymerisation), though Fricke's comparison to Ag⁺ and Au⁺ suggests to me that it is on the basic side of amphoteric. Extrapolations of Ts are hard to find but I agree that it could form Ts₂O₃ but not Ts₂O, which would parallel Au as Fricke suggests. (Admittedly that would suggest the possibility of Ts^V with extremely strong oxidisers. I guess I could maybe believe in TsF₅ forming if you tried oxidising Ts with KrF₂, but I'm not terribly convinced about a 5 state.) If you asked me outright, I've come round to believing in a metallic Og, mostly because of the 7p_1/2-8s gap shrinking (which is why we can think about 119³⁺, after all); I just have a tiny bit of doubt that would be dispelled by a detailed calculation being performed.) Note that without relativity Pb and Fl would have the diamond cubic structure, so that we already have a warning. ^_^ Double sharp (talk) 23:43, 14 March 2018 (UTC)

P.S. This actually suggests an amusing joke explanation of why E172 as a nonmetal doesn't seem so unreasonable. If we continue to move the line to the right two groups at a time, we get from At to the space after Og, except that E119 is already in the next period. Then, following the Madelung rule, E168 would be under Og (and indeed it is probably a predominantly tetravalent metal like Sn, continuing the trend). But now the period is lengthened and we are redrawing it so that the "knight's move" and "double knight's move" relationships have become vertical, so that the line goes to E171 (three spaces after E168), and it's not yet the end of the period: E172 is still there! Which gives a silly way of drawing the 8th row; simply follow the Madelung rule till E168, and then tack E169 through E172 jutting out at the end of the row. (Please note that I am not being serious. ^_-☆) Double sharp (talk) 01:47, 15 March 2018 (UTC)

Calculations on the structures of NhOH, AtOH, and TlOH (10.1016/j.cplett.2015.08.017) suggest that Nh^I is more similar to At^I than Tl^I, because the shell closure at Fl mimics the shell closure at Rn. Since AtOH is probably amphoteric (both hypoastatous acid as well as astatine(I) hydroxide), this combined with the expected polymerisation of NhOH on the way to forming Nh₂O (which would look a lot like the olation reactions of transition metal aqua complexes) suggests indeed that Nh^I would be amphoteric (green), albeit probably leaning towards the basic side of amphoteric. Given this "role reversal" of groups 14 and 18 with Fl and Og, it seems quite likely that Ts is more like Ga or In. If comparisons with Au are anything to go by, given the similarities of Ts³⁺ and Au³⁺, then TsOH is likely to be unstable (though adducts of it might exist), with the only oxide being Ts₂O₃ in the major oxidation state; this would be more reminiscent of Ga than In. So on some further revision, I think you are right, and would revise my colouring to:

• Nh: 1 green (capital)
• Fl: 2 green (capital)
• Mc: 1 blue (capital), 3 green
• Lv: 2 blue (capital), 4 green
• Ts: 1 grey, 3 green (capital)
• Og: 2 green, 4 green (capital)
• Uue: 1 blue (capital), 3 green
• Ubn: 2 blue (capital)

This suggests a swap where Ts and Og act like lighter metallic group 13 and 14 elements respectively (especially Ga and Sn), while Nh and Fl act more like At and Rn (although Fl would be significantly more metallic than Rn, having the band structure of at least a semimetal, this is exactly what we would expect one row further down the table). Mc and Lv then take an intermediate position, something like Tl and Pb (although Lv is larger and it shows in its basic +2 state, unlike the amphoteric +2 state of Pb). Uue would similarly have some Tl-like behaviour (and we shouldn't forget that Tl⁺ was widely considered an alkali metal cation for some time during the 19th century), while Ubn would return to normality for group 2 (albeit more like Ca or Sr than Ba or Ra). Very little information is available above element 120, but at least we can be somewhat confident in saying that element 121 should have only a 3 in blue. Double sharp (talk) 07:16, 15 March 2018 (UTC)

@Double sharp: You mean 7p_3/2-8s gap shrinking I guess. Yes, now your colouring is exactly what I'm thinking of :) As for Nh(I): I'd expect it to be between Au(I) and At(I), but far from Tl(I). Mc(I) would be much closer to Tl(I) instead. BTW, I hanker for the calculations of Au-At, Au-Rg, Au-Nh and Au-Ts molecules. Droog Andrey (talk) 17:50, 15 March 2018 (UTC)

Updated. Droog Andrey (talk) 21:16, 15 March 2018 (UTC)

@Droog Andrey: Yes, it's an effect of the 7p splitting that results in a valence shell closing at Fl and hence makes Nh and Fl a "subperiod" for 7p_1/2, while the destabilisation of 7p_3/2 makes Mc act like the start of a new shell and brings it close to 8s (so that 7p_3/2 are likely still valence electrons at E119). Thank you very much for the updated version! ^_^ I do have some misgivings about Rg^−I and Nh^−I which have just been added, because the predicted electron affinities are lower than those of Ts (see electron affinity (data page)). I agree that Nh and Fl are likely to be very bad homologues of Tl and Pb and that your suggested homologues of Au and At for Nh are likely to be better (similarly Hg and Rn for Fl); I think Mc and maybe Lv would be better homologues of Bi and maybe Po in their lower oxidation states. I like the capitalisation of the lower oxidation states starting from Hs, since IIRC they are predicted to start becoming important around there (maybe Bh too; I'll check the predictions later). I still have some comments elsewhere on the table regarding oxidation states which will also come soon. ^_^ I'll search around for predictions on MAu (M = At, Rg, Nh, Ts). Double sharp (talk) 23:46, 15 March 2018 (UTC)

@Droog Andrey: Here is an interesting recent paper in that direction (it covers the adsorption of At and AtOH on Au surfaces, with some notes about the expected behaviour of Nh and NhOH). I will keep looking for more predictions. Incidentally the resemblance of Ts³⁺ to Au³⁺ is rather amusing given the resemblance of At⁺ to Ag⁺. ^_^ Double sharp (talk) 04:30, 16 March 2018 (UTC)

@Double sharp: electron affinity is not everything: nitrogen has zero, but is quite electronegative :) Droog Andrey (talk) 05:09, 16 March 2018 (UTC)

@Droog Andrey: True, though part of that is the small size of N (P and As are much less electronegative) and early calculations aiming to see if Rg⁻ would be a thing focused on the expected EA. Well, the alkalides Na⁻ through Cs⁻ all exist with much lower electron affinities, so we cannot rule either of them out especially given the analogy of Nh to At and Rg being a good homologue of Au. BTW you might be interested in the Fermi-gas-like structure of the electron cloud of Og with shells smeared almost to nothing (10.1103/PhysRevLett.120.053001), which would presumably increase reactivity even further (and it suggests to me significant delocalisation in the solid state if many electrons are able to contribute). I also notice that metallic At is expected to be a superconductor like a similar high-pressure phase of iodine and I wonder if that might mean something for tennessine or perhaps nihonium. ^_^ Double sharp (talk) 05:55, 16 March 2018 (UTC)

@Double sharp: yes, atomic radius is the key to EA(Rg) < EA(Ts). Rg and Nh are smaller than Au and Tl, yielding larger electronegativities; Ts has larger size and lower electronegativity than At. Nh-Ts molecule is predicted to have negative charge on Nh atom, you know. Droog Andrey (talk) 06:09, 16 March 2018 (UTC)

@Droog Andrey: I do believe I've overlooked the obvious here (or rather stated it without realising its implications); yes, you are right. I wonder if it'd be possible to show numerical values for the atomic radii on your table without cluttering the whole thing up? The differently sized circles are beautiful but a little hard to compare when they aren't next to each other. Yes, I've heard of NhTs having negative charge on Nh rather than Ts: it's in the tennessine article and I've said above in my review that Ts should be less electronegative than Nh, thinking of that study (though I should've mentioned it explicitly). Double sharp (talk) 06:22, 16 March 2018 (UTC)

@Double sharp: some deep analysis changed my mind about Nh(III) and Mc(III). Droog Andrey (talk) 13:46, 23 March 2018 (UTC)

@Droog Andrey: Interesting! Could we have a summary of what was the factor for including Nh^III? Mc^III I can understand given that the gap between the 1st and 2nd ionisation potentials is actually a bit smaller than those for Ga and In, and Keller et al. suggest that both I and III would be major oxidation states for Mc, but what did we overlook about Nh^III in our previous analysis based on the high 2nd ionisation energy of Nh? (I imagine, like in the paper of Seth et al. I linked to, that Nh^III would be predominantly stabilised in anionic complexes similar to those of Cn^III and Cn^IV. I suppose Nh^V is probably still too much for Nh.) Does Nh^II disproportionate as I would expect (Hoffmann et al. raise it as a possibility)? Incidentally CCSD calculations (10.1103/PhysRevA.53.3926) indicate that Nh²⁺ has a d¹⁰s¹ configuration (though d⁹s² is only at 0.1 eV, whereas it is at 8 eV for Tl²⁺), so your dications page probably needs an edit for Nh. ^_^ Double sharp (talk) 15:17, 23 March 2018 (UTC)

@Double sharp: Nh³⁺ has d¹⁰s⁰, so 6d isn't screened anymore, and we have a gap between IP3 and IP4. In NhF₄^- 7s is somehow restored by fluorine ligands, and there's a large degree of correlation between F 2p and Nh 7s. Now I expect NhF₄^- to be at least as stable as AgF₄^-. Droog Andrey (talk) 16:49, 23 March 2018 (UTC)

@Droog Andrey: Hmm, that's very interesting. Rereading the original paper of Seth et al., they note that NhF₃ and NhCl₃ are T-shaped rather than trigonal planar, but unlike ClF₃ it is difficult to attribute this to lone pairs (because there would be too many lone pairs to give such a structure by the VSEPR rules). NhBr₃ and NhI₃ are instead trigonal planar, perhaps because of the increased steric repulsion between the peripheral halogen atoms. They compare the case of NhF₃ to AuF₂⁻ and HgF₂, where only 6s is involved in bonding: NhF₂⁺ is valence isoelectronic with them and can easily take up more fluoride ligands (going to NhF₃, or better still, NhF₄⁻) via backbonding into the vacant 7p orbital (kind of like boron). The relativistic contraction of the Nh–F bonds and the still significant electronegativity difference between them should certainly further stabilise this complex anion. You really should publish your wonderful calculations, so that we can cite them for Wikipedia. ^_^ I suppose it's too much to ask for FlF₆²⁻? Double sharp (talk) 03:36, 24 March 2018 (UTC)

@Double sharp: there are much more calculations waiting for publication :) As for FlF₆²⁻, I believe it will be unstable against FlF₃^- + F₃^-. Droog Andrey (talk) 08:32, 24 March 2018 (UTC)

P.S. Updated the dications page and refined the electronegativity scale for closed-shell atoms, including noble gases. Droog Andrey (talk) 20:21, 24 March 2018 (UTC)

@Droog Andrey: Thank you! Regarding the electronegativities of the noble gases, I think you'd find 10.1021/jp5098876 interesting. Double sharp (talk) 04:16, 25 March 2018 (UTC)

@Double sharp: an interesting approach, thank you :) Unfortunately, they didn't check the dependence on basis set diffuseness. And I'd use the values for 1/ε → 0 instead :) As for my method, it is based on atomic charges in linear [ZXZ]⁺ species, where Z is from the closed-shell group and X is from the previous group, e.g. [NeFNe]⁺, [ArIAr]⁺, [ZnAuZn]⁺, [HgAgHg]⁺, [SrLiSr]⁺ and so on. Droog Andrey (talk) 08:46, 25 March 2018 (UTC)

@Droog Andrey: It's certainly interesting, even if I admit that I didn't understand everything in it. ^_^ What I was intrigued by was one portion of the results that the paper agrees with you on – that the noble gases are not more electronegative than the halogens as the Pauling values imply, and that they are actually closer in electronegativity to the chalcogens. That especially makes me wonder if the the value of 4.50 for Ne (which no doubt continues the step-of-0.5 series across period 2) ought not to be changed to something closer to 3.80, as the trend would suggest. I'm also not sure if He should really be less electronegative than Ne. Double sharp (talk) 10:38, 25 March 2018 (UTC)

@Double sharp: He and Ne are the most electronegative in their periods because of filled shells. Ne is more electronegative than He because of larger density of valence electrons. Second period is just a bunch of anchoring points, you are right :) Droog Andrey (talk) 11:17, 25 March 2018 (UTC)

@Droog Andrey: That makes intuitive sense, though I'd really like to see a write-up for a calculation (presumably with your choices of values) that gives that result for He and Ne. There really are many things about your table and your calculations that I'd love to mention on Wikipedia if I could cite something for it. ^_^ Incidentally, the anomalously lower EN value for He than Ne (kind of like what happens if you put H on top of F) reminds me of this 2017 article by Wojciech Grochala suggesting that helium be moved to group 2 atop beryllium. I still find myself uncomfortable which such an idea, given the inertness of He being so much closer to that of Ne than the chemistry of Be, and would rather consider the regularities he points out to be simply a secondary course-correction based on the shared s² configuration of He and Be. Yet I cannot deny that it is intriguing. Double sharp (talk) 04:29, 26 March 2018 (UTC)

@Droog Andrey: P.S. I put your electronegativity values in a sortable wikitable at User:Double sharp/Electronegativity (I hope that's OK with you?) and it really is interesting to sort the values in ascending order and see the "electronegativity series", to quote Burzuchius at Talk:List of oxidation states of the elements#Argon - +2? ^_^ Double sharp (talk) 12:53, 26 March 2018 (UTC)

@Double sharp: yes, that's OK. Thanks a lot!

Which calculations are you interested in? Droog Andrey (talk) 15:33, 31 March 2018 (UTC)

@Droog Andrey: I'd love to say "all of them", but the most important ones are the ones I cannot find anywhere else: copernicium(III), your predictions about the higher oxidation states of Nh and Fl in anionic complexes, metastable Cs[CsF₈], and the no doubt multitude of treasures you're planning to uncover or haven't mentioned here yet. I'd also love to have a write-up on your electronegativity scale so that we can write about it on Wikipedia. ^_^ Double sharp (talk) 15:40, 31 March 2018 (UTC)

@Double sharp: That's maybe only 1% of what I have :) I hope to publish some of this, but definitely not all of this. This year I'm concentrated on other results, so the electronegativity scale could be published next year (at best). Droog Andrey (talk) 12:23, 1 April 2018 (UTC)

@Droog Andrey: Please, take as much time as you have to! If I could only request one of the above, it'd be the higher oxidation states of copernicium, but I'll be happy waiting for all of them (including that one) to come out. Double sharp (talk) 14:07, 1 April 2018 (UTC)

Oxidation states

@Droog Andrey: What are the inclusion criteria for oxidation states listed on your periodic table? I see many of the formal negative oxidation states for the transition metals in carbonyl complexes are not included, for example. Even if we're ignoring these, I think americium is missing a 7. Double sharp (talk) 06:11, 21 March 2018 (UTC)

@Double sharp: oxidation state is a formal parameter to describe the state of valence shells. AAR, there's fairly good correlation between oxidation states and chemical properties, but sometimes the former is getting too formal, particularly in organic/carbonyl complexes like Disodium tetracarbonylferrate.

Do you have any reliable sources on Am(VII)? My sources say it's just as doubtful as Pu(VIII). Droog Andrey (talk) 09:47, 21 March 2018 (UTC)

@Droog Andrey: OK, so we're including oxidation states only when they make sense (i.e. aren't too formal), which I wholeheartedly support. ^_^

About Am^VII: our actinide article (citing Greenwood and Earnshaw) mentions it without comment in AmO⁵⁻
₆ (though probably this is not the real formula with such a high negative charge). I will check some more specialised sources on this (e.g. The Chemistry of the Actinide and Transactinide Elements). OTOH, Greenwood and Earnshaw don't include Cm^VI. Double sharp (talk) 10:01, 21 March 2018 (UTC)

Greenwood and Earnshaw was published before the approval of Cm(VI) (10.1134/S1066362211050018). Droog Andrey (talk) 12:17, 21 March 2018 (UTC)

@Droog Andrey: Interesting! I was aware of CmO₂²⁺ and CmO₃, but was not sure how generally accepted they were. The plot thickens on Am^VII: it is not actually in Greenwood and Earnshaw, despite the reference. German Wikipedia has a similar colour chart cited to Holleman & Wiberg; the English translation says on p. 1726 "The heptavalency of americium is still uncertain. This extremely unstable oxidation state was reported to be formed by disproportionation of Am(VI) salts in strongly alkaline solution (2 AmO₂(OH)₂ + 3 OH⁻ → AmO₂(OH) + AmO₅³⁻ + 3 H₂O) or by anodic oxidation of Am(IV) in alkaline solution at 0 °C." The Chemistry of the Actinide and Transactinide Elements (3rd ed.) has on p. 1327 in the americium chapter: "Am(VII): While attempts to synthesize Am(VII) from Li₂O–AmO₂ mixtures at 300–400 °C failed, oxidation of 3–4 M NaOH solutions containing 0.001–0.002 M Am(VI) with ozone at 0–7 °C yields a green‐colored solution of Am(VII) (Krot et al., 1974a,b; Myasoedov and Kremliakova, 1985). A similar green‐colored solution can be obtained by ⁶⁰Co gamma irradiation at 0 °C of a N₂O‐saturated 3 M NaOH solution. (N₂O scavenges hydrated electrons by the reaction N₂O + e⁻ (aq) → N₂ + O⁻; S₂O₈²⁻ may be substituted for N₂O.) Spectrophotometric studies showed the oxidation of Np(VI) to Np(VII) and Pu(VI) to Pu(VII) under similar conditions, which provides strong evidence that the green solutions indeed contain a powerful oxidant such as Am(VII) (Krot et al., 1974a,b)." Double sharp (talk) 15:00, 21 March 2018 (UTC)

@Double sharp: so we have only a few old sources. I prefer to consider that too exotic; counting every possible oxidation state would encumber the table and mix exotic oxidation states with common ones. E.g., nitrogen(+1) is also missing in spite of Na₂N₂O₂, CF₃NO and so on. Droog Andrey (talk) 16:41, 21 March 2018 (UTC)

@Droog Andrey: Okay, I think I understand your criteria better: I guess the exclusion of the alkalides is also made for similar reasons. I must admit though that I haven't come across sure references to Rn^IV: I know of the experiments generating a volatile radon fluoride that hydrolyses to form RnO₃ (which I mentioned above while discussing Og) but that could be either RnF₄ or RnF₆ (though I agree the former is more likely). As for colourings, XeO₂ has fairly recently been found and so Xe should presumably have 4 in red as well. Double sharp (talk) 23:54, 21 March 2018 (UTC)

@Double sharp: I'm aware of XeO₂, but AFAIK it didn't show neither acidic, nor basic properties. Droog Andrey (talk) 12:04, 22 March 2018 (UTC)

@Droog Andrey: The original paper detailing the discovery of XeO₂ mentions its acidity in the supporting information: "As a non-metallic oxide, XeO₂ is acidic and insoluble under acidic conditions, but under basic conditions, it rapidly decomposes to Xe and O₂. This is in accordance with the stabilization of the yellow solid under acidic conditions in an earlier hydrolysis study, and likely accounts for the absence of XeO₂ under the fluoro-basic conditions that result from the use of excess fluoride in the synthesis of XeOF₃⁻." Double sharp (talk) 14:23, 22 March 2018 (UTC)

@Double sharp: anyway, still no xenates(IV) were obtained. Droog Andrey (talk) 17:00, 23 March 2018 (UTC)

@Droog Andrey: OK, fair enough. ^_^ BTW, I was curious about a few changes from the 2017 edition: Yb(III), Lu(III), Cu(II), Cd(II), and Hg(II) oxides have changed from amphoteric (green) to basic (blue), and Cm(II) and Bk(II) have disappeared. Could you clarify with your characteristic insight what spurred these changes? Certainly most of the elements from group 11 onwards have greater or lesser amphoteric tendencies and I'd like to know more about where the line is being drawn here. Double sharp (talk) 15:51, 31 March 2018 (UTC)

@Double sharp: we just narrowed the bounds for amphoterism to avoid the conflict with our schoolbooks where Cu(II) is treated as basic (indeed, Cu(OH)₄^2- is more about complex formation than about acidity, as well as Fe(OH)₄^2- and Mg(OH)₄^2-). Cm(II) and Bk(II) were considered as too doubtful (cf. LnI₂).

You may also check the back side featuring solubility table :) Droog Andrey (talk) 12:37, 1 April 2018 (UTC)

@Droog Andrey: I feel more than a little silly now, never having thought the "front" in the URL might imply that there was also a "back". ^_^ Indeed Cu(OH)₃⁻ and other such anionic species only appear at low Cu concentrations and high pH (link). I suppose the whole thing is a continuum and many lines can be justified for various reasons. After all, we're colouring As(III) as acidic, even though As₂O₃ will react with concentrated HCl to form AsCl₃. (Mind you, according to Post-transition metal#Group 15, some authors consider this more analogous to alcohols than to bases. Incidentally the same article describes Ge(IV) as amphoteric and Bi(III) and Po(IV) as predominantly basic, but I think this is again just a question of where the line is being drawn.) Double sharp (talk) 14:04, 1 April 2018 (UTC)

New 2018 papers on superheavy elements

New calculations on solid copernicium suggest that Cn is a metal with the bcc structure because of 6p involvement.

From the abstract of a new paper on TlOH and NhOH: "Results show that Nh should be less reactive (or more volatile) than Tl, both with respect to gold and the hydroxyl group. ... NhOH may be less volatile than TlOH due to its larger both dipole moment and anisotropic polarizability." Double sharp (talk) 15:48, 23 March 2018 (UTC)

Towards chemical studies of Fl and Mc based on their thorium-series homologues ²¹²Pb and ²¹²Bi. Double sharp (talk) 06:06, 19 April 2018 (UTC)

PT files: cleanup, and stop spreading versions

We need to cleanup the PT files at commons. At the moment, loads of variants are available, while only a few are consistently maintainedto be in line with the enwiki PT choices. Thys way, outdated and not-maintained PT's images are used in other wikis (interwikis). This should be discouraged.

Example: for User:Sandbh/Nonmetal redraft, Sandbh created and uploaded this development version File:Periodic Table Chart with reactive nonmetals in yellow.png (1). Already, we have two similar versions: this one (2) in Periodic table, and this one (3) in nonmetals. (2) and (3) are the same.

This causes the following problems:

a. They are the same, true copies but for minor details

b. We are supposed to maintain all with every change

c. Other wikis (interwiki, sister wikis) end up using a wrong, outdated, not-maintained version.

I propose to do:

1. Deprecate, warn, categorise and remove from commons development and outdated versions that have served (like (1) when it's live)
2. Propagate usage of a single file per PT version, enwiki-maintained and supported (that is: in accordance with any current enwiki PT setup). Could include svg-language.
3. Support other wiki's to use the correct enwiki designs when desired.
4. Long term, make files & filenames more systematic

-DePiep (talk) 08:18, 24 April 2018 (UTC)

• As for the examples: it appears that File:Simple_Periodic_Table_Chart-en.svg (2) is a recent fork is in preferred svg format, (over png File:Periodic Table Chart.png), so (2) should be the remaining one. -DePiep (talk) 08:26, 24 April 2018 (UTC) (svg over png)

PT colors: font color contrasts

In short: the 2013 color set has State of Matter colors used as fontcolor. Currently, these produce bad contrast with the backgrounds, making text hardly readable. I propose to boldly change the SoM-colors a bit, which will bring three more colors into conforming. The changes are minor. (W3C conformance, WP:ACCESSABILITY, contrast checks). - DePiep (talk) 07:30, 25 April 2018 (UTC)

Background: To signal the state of matter at STP (SoM) in a Periodic table, we use these fontcolors for atomic number:

• A  Solid2013 → #000000 
• A  Liquid2013 → #008000 
• A  Gas2013 → #ff0000 
• A  Unknown phase2013 → #696969 
• A  wikilink → #0645ad  (to check too)

This 2013 color set appears in some 18 combinations in the periodic table (existing category × SoM combinations).

Contrast checks are part a w3c guideline, called Web Content Accessibility Guidelines 2.0, WCAG20. The calculated result for a fontcolor/bgcolor RGB/RGB pair is called "conformance": being "AAA" (very good), "AA" (good) or "none" (bad). It affects readability, and is part of our WP:ACCESSABILITY.

Not all 2013 colors do contrast well enough with background (category) colors we use. See the analysis here: nine fail.

I propose to change the SoM colors into a slightly darker color:

• A #000000, Solid (unchanged)
• A #cb0000, Gas
• A #007000, Liquid
• A #606060, Unknown phase

This will make three more combinations conforming: see here. The remaining six nonconforming combinations can only be changed by changing the background color, which is not trivial.

The downside is that the changed red, green and grey colors do stand out less. They are less bright, and less recognisable (they are more towards black). However, since not conforming is worse we should accept this aspect. After all, not conforming to accessability means that the text (atomic number) is "not readable" at all.

I plan to make this change boldly since the changes are minor, and we don't have much choice (cannot leave bad fontcolors while the alternative is almost free at hand). It will be made together with the other 2103 color set to be made: add category Reactive nonmetal, and remove "predicted" categories altogether. It does not affect the outcome of the more fundamental question R8R made: should we indicate SoM at all? (See #Proposal: eliminate colors for states of matter: whatever the outcome, we can and will apply that). - DePiep (talk) 07:30, 25 April 2018 (UTC)

 Done. See e.g. {{Periodic table}}, and #Periodic Table colors: updating the 2013 color set. -DePiep (talk) 13:28, 25 April 2018 (UTC)

Periodic Table colors: the 2013 update 2018a set

Per Wikipedia_talk:WikiProject_Elements#How_to_proceed_with_reclassifying_nonmetals?, the following changes have been applied to the Periodic table color sets (legend themes):

• Add category Reactive nonmetal  #f0ff8f ,

remove categories polyatomic metal #a1ffc3, diatomic metal #e7ff8f (Discussion: at #Reclassifying_the_nonmetals, at #How_to_proceed_with_reclassifying_nonmetals?)

• Remove categories "predicted" like alkali metal (predicted) #d8bcbc, superactinide #d1ddff (Discussion: at #Oganesson)
• Remove SoM's (phases) "predicted" (Discussion: at #Oganesson)
• Adjust fontcolors for SoM to improve contrast (Bold statement: at #PT_colors:_font_color_contrasts)

The new set may be referred to as "2013 update 2018a". - DePiep (talk) 11:48, 25 April 2018 (UTC)

Effects are visble in, for example:

{{Periodic table}}, File:Simple Periodic Table Chart-en.svg

{{Periodic table legend}} (categories), {{Periodic table (32 columns, micro)}}

{{Periodic table (18 columns, large cells)‎}}, {{Extended periodic table (by Fricke, 32 columns, compact)‎}}

Periodic table, Unbinilium, Extended periodic table

- DePiep (talk) 13:45, 25 April 2018 (UTC)

Isotope lists: Nuclear spin should be Nuclear spin and parity

There is a mislabelled column in all the articles Isotopes of [Element name]. In the List of isotopes, there is a column labelled Nuclear spin. However most of the spin values are followed by a sign (+ or –) which indicates the parity of the isotope, normally in the ground state except for metastable states labelled with an m. For example in Isotopes of tantalum, the lightest isotope in the table is ¹⁵⁵Ta for which the Nuclear spin column shows (11/2−). This actually means that the spin is +11/2 and the parity is negative, but nowhere is this explained either in this article or anywhere else in Wikipedia that I have found.

As an example of the confusion which misidentification of the sign can cause, see Nuclear isomer, where the article until yesterday said that the spin of ^180mTa is –9 (sic), which should have been 9– (spin 9, parity –). At Talk:Nuclear isomer#9 + 1 = 8, an editor noticed that the arithmetic comes out wrong if the spin is taken as –9. I fixed the Nuclear isomer article by just removing the minus sign which adds nothing to that article.

However for the Lists of isotopes, clearly we should not remove the parity from all the tables which would be suppressing information about the isotopes. Instead I propose that we clarify the meaning of the signs in one of two ways: (1) change the column headings to read Nuclear spin and parity. Or (2) place the nuclear spin values in one column and the parity in a second (new) column.

Comments on these alternatives (or others)? Also, does anyone know how to automate the process so that the isotope lists for all 118 elements can be changed efficiently?

Dirac66 (talk) 00:39, 20 April 2018 (UTC)

I like "nuclear spin and parity". If no one has a better solution or objects to this one, then I'll start fixing all 118. Double sharp (talk) 04:08, 20 April 2018 (UTC)

Good opportunity to make the header a template? - DePiep (talk) 12:21, 20 April 2018 (UTC)

First try did not work out well with {{Isotopes table/header}}: variants between isotope pages (esp wrt abbreviations in group "n"). Later more. - DePiep (talk) 16:21, 20 April 2018 (UTC)

Even if you fix the template as desired, it still has to be inserted manually for each element. So Double sharp's offer to insert and parity for 118 elements is just as simple. It would also allow for more flexible - for example I note that your template includes a new column for Historic name, for example mesothorium for Ra-228 and such. If the columns are inserted manually, this column can be restricted to the heavier elements which actually have isotopes with obsolete names.

Also I have now revised the parity article to explicitly mention the parity of nuclei, so the article is now more relevant to these lists.Dirac66 (talk) 23:54, 23 April 2018 (UTC)

I have now started manually by adding "and parity" for H, He, Li, Be, B, C. I plan to continue in the next few days, but if someone else wants to do some elements I will not object. Dirac66 (talk) 23:51, 24 April 2018 (UTC)

 Done for Category:Lists of isotopes by element (122). - DePiep (talk) 08:20, 25 April 2018 (UTC)

BTW, shouldn't/couldn't this header be wikilinked? - DePiep (talk) 09:49, 25 April 2018 (UTC)

OK, thanks. I see that you succeeded in automating the process. As for wikilinking the header, I would say go ahead and link to it wherever you think the link is relevant. Dirac66 (talk) 10:14, 25 April 2018 (UTC)

Good you took a break and posted here ;-). As for the link(s), I take my advice from Double sharp. I see Parity (physics), Nuclear spin. Elsewhere in the header more? - DePiep (talk) 14:34, 25 April 2018 (UTC)

Well, we could link these words in each header as well. Also perhaps half-life and decay mode, which may not be clear to every reader. Dirac66 (talk) 01:31, 26 April 2018 (UTC)

Proposal: eliminate colors for states of matter

@DePiep, Double sharp, Sandbh, and YBG: This has bugged me for a while already. In the large periodic table cells, we color the atomic numbers by the state of matter of the simple substance at STP. I would like to eliminate this coloring for one obvious reason: the periodic table lists elements, not simple substances, and so properties of simple substances do not belong in a periodic table.--R8R (talk) 15:01, 24 April 2018 (UTC)

I don't agree with this. Categorisation itself is based on physical as well as chemical properties, and doesn't the former imply that we are considering simple substances? When we say that something is a metal, we are not just saying it based on its chemistry, but also because as a simple substance it is a good conductor of heat and electricity, among other criteria. Double sharp (talk) 06:24, 25 April 2018 (UTC)

State of matter depends on temperature, pressure and allotropy, that's not an inherent property of an element. Suppose the boiling point of Fl metal is measured as low as +15 degrees, which state is to be chosen then? Droog Andrey (talk) 08:00, 25 April 2018 (UTC)

I've been thinking something along the lines of what Droog Andrey said. On top of that, I assume chemistry is the main reason we classify elements as metals or nonmetals. Brittleness, hardness, and such can be complimentary at best. We don't classify iodine as a metalloid even despite its brittleness. Melting/boiling points are clearly insufficient on their own. Both mercury and bromine are liquids in their elemental forms; what do we learn from that in terms of categorization? Gallium and cesium have low mp, too, what about them? On their own, these mp/bp values of simple substances are only an excerpt of the story of the elements, and not even a perfectly characteristic one.--R8R (talk) 09:05, 25 April 2018 (UTC)

But metallicity isn't an inherent property of an element either, or else we can simply put the pressure up past 100 GPa and then Cl, Br, and I conduct electricity like metals. Furthermore, at such pressures helium isn't inert either (though it's still not a metal), forming disodium helide, which is an illustration that chemistry itself also depends on pressure. Double sharp (talk) 11:58, 25 April 2018 (UTC)

As I said, a point of mine is, mp/bp is not a particularly characteristic property even at STP. I cannot truly accept your argument as I don't think I have referred to anything about such unusual high pressures apart from Droog Andrey's comment.--R8R (talk) 12:17, 25 April 2018 (UTC)

OK, but if you are excluding as unusual high pressures where chemistry is very different and potassium is a transition metal, then you are implicitly assuming standard pressure as a default. In other words, you are already not considering the elements as potentially being found in any circumstances, but limiting them to those that can be found at standard pressure. And this is already implicit in the way you draw the periodic table, or else you have to redraw the whole thing at pressures when potassium has an [Ar]3d¹ configuration. So by drawing and colouring the periodic table in the way we know and love, we are already presupposing how they behave at standard pressure, and not in weird compounds like Na₂He at 113 GPa. Given that, we have already retreated from the idea that we are not considering elements as substances.

Based on text at chemical element, I get the feeling that this issue comes about because some languages make a distinction between elements and simple substances, having specific terms for the latter as distinct from the former: French and Russian do this, for example. In English, words like "elementary substance" and "simple substance" do not have much currency. To me it feels kind of like the sort of distinction that is good for cutting off a few points on the test and that you forget about completely when you get beyond the basics because it's not really illuminating anything. The moment you start considering enthalpy changes you immediately have to declare as standard one set of conditions, one state for each element, and one allotrope for each element. So much for the distinction between elements and simple substances: in practice one manifestation of the element as a simple substance and its state at STP has to be placed above all the others, even if it isn't the most stable (like the use of white phosphorus rather than black phosphorus). Why should we not include this useful information? Double sharp (talk) 14:39, 25 April 2018 (UTC)

P.S. An intriguing comment from that article I linked about high-pressure potassium chemistry: 'Strictly speaking, an element is defined by the number of protons in its nucleus, but chemists also associate a certain electronic structure and characteristic chemistry with certain groups of elements. [paragraph break] "I think you can argue that when you change the chemistry of potassium from that of an alkali-like s-electron element to that of a transition-metal-like d-electron element, you've pretty much got a new element," Badding says.' Double sharp (talk) 14:53, 25 April 2018 (UTC)

Come to think of it, I indeed am implicitly assuming standard pressure as a default. Because even the main categorization---the one we use to color the cells of the PT---relies on these conditions. As you rightly notice, potassium is a TM at high pressures. If we did not have a condition to stick to, all of our categorization would be null.

But then again. English does have a good way to refer to a simple substance---by the word "elemental," e.g. "elemental chlorine"---and the concept still pretty much exists. The thing is, the periodic table does not feature elemental chlorine, it only features chlorine, that is all there is to it. At this one set of conditions, chlorine can be a free gas, a part of a solid salt, a part of some organic liquid, and so on. And that is all the PT is about---about elements, not simple substances. But having to declare a set of conditions in no way implies you also have to stick to a particular allotrope or a particular state, these are not related to elements as to substances formed by that element.--R8R (talk) 09:58, 28 April 2018 (UTC)

Isn't the use of elemental as an adjective evidence that English thinks the other way? If we talk about Cl₂ as elemental chlorine, and contrast that with the chlorine atoms found in compounds such as NaCl or PhCl, then it seems to me that elemental as an adjective defines precisely what you're calling a simple substance. If we look at the IUPAC Gold Book definition of "chemical element", we see as the first definition "1. A species of atoms; all atoms with the same number of protons in the atomic nucleus", and as the second definition "2. A pure chemical substance composed of atoms with the same number of protons in the atomic nucleus. Sometimes this concept is called the elementary substance as distinct from the chemical element as defined under 1, but mostly the term chemical element is used for both concepts." That implies to me that the chlorine atoms in NaCl or PhCl are indeed representatives of the element chlorine as a species of atoms, because they have 17 protons in their nuclei; but that an element is not only a species of atoms, but also a substance composed purely of atoms belonging to that species, and in the case of chlorine, once you select STP as standard conditions, it must be gaseous Cl₂. Since the periodic table is showing chemical elements, and at least in English that also includes simple substances either as a noun or as an adjective, why should we not include state-of-matter information about them? Double sharp (talk) 15:50, 28 April 2018 (UTC)

I add: the SoM does not show much of a trend does it? The two liquids Br, Hg are locatedm.p., b.p.) or is it a concept (the Z)? IOW, the definition of an element does not have a SoM (or an allotrope, or diatomic molecules like F₂). And then, what is it in the periodic table? DePiep (talk) 13:23, 25 April 2018 (UTC)

If Fl metal is a gas at STP it would be shown as a gas. I don't yet understand what is to be gained by getting rid of the state of matter colours. Sandbh (talk) 09:37, 25 April 2018 (UTC)

We would stop giving exaggerated importance to a property that is not all too important. We are essentially limiting an element to a simple substance there, which is an uncalled for substitution. The periodic table lists elements, not simple substances, and should refer to properties of those elements, rather than substances. Most people have seen lots of sodium in the table salt but rarely, if ever, seen the metal. DePiep below captures my thoughts exactly.--R8R (talk) 12:17, 25 April 2018 (UTC)

• R8R is addressing a core issue. This is about abstraction of elements: is it stuff (with an m.p., b.p.) or is it a concept (the Z)? IOW, the definition of an element does not have a SoM (or an allotrope, or diatomic molecules like F₂). And then, what is it in the periodic table?

Over at Wikidata, people as describing the orthography (say, classifications & relationships) of chemistry. See this discussion d:Wikidata_talk:WikiProject_Chemistry/Archive/2017#A_specific_chemical_element_(Q11344)_is_a_class? December 2017). It appeared that element carbon (Q623) was both a classmember (~"graphite is a carbon"), and a material ("graphite has m.p. ...").

R8R here raises the point what those material properties have to do in the periodic table? The periodic table describes the concepts of the elements, not their real life appearances. Of course, individual elements are correctly described with their RL properties (in their article). For this reasons, I think the SoM at STP is not a core property to be listed in (main) periodic tables. As we do not list the crystals in there. (Schoolbooks may think different, if only to get students interested in the PT, but still). - DePiep (talk) 10:09, 25 April 2018 (UTC)

I remain in agreement with Double sharp. It is interesting to note that metals and metalloids are nearly all solid, whereas the nonmetals number among their kind solids (5), a liquid (1), and gases (11). The question is why? And among the metals why are the melting points of e.g. Rb, Cs, Hg, Ga so low? The first question is related to a progression in bonding type going across the table from L to R. The second question is associated with the number of electrons available for metallic bonding; relativistic effects; and the peculiar bonding found in Ga. I think most of this is related to the L-R trend in metallic to nonmetallic character going across the table + the trend of increasing metallic character going down the table, both of which are well recognised periodic trends.

And see these for the weird things that happen to the elements under pressure.

https://arxiv.org/pdf/1503.00230.pdf

https://www.nature.com/articles/nature07786

You would have to draw up a new high pressure periodic table:

"Slowly, however, modern-day alchemists are ratcheting up the pressure. As they do, they are transforming the familiar physical and chemical properties of elements from hydrogen to iron, turning liquids to solids, non-metals to metals and more besides…“We essentially have a new periodic table at high pressures,” says materials scientist Paul Loubeyre of the Alternative Energies and Atomic Energy Commission (CEA) in Bruyères-le-Châtel, France." Sandbh (talk) 06:59, 26 April 2018 (UTC)

Periodic Table colors: to improve the micro table

Is there a way to better visually distinguish discovered but uncharacterised elements from undiscovered elements? On the micro periodic table at extended periodic table, there is no visual difference between Og and E172, and you have to know from somewhere else which ones are discovered and which ones aren't (just predicted). If we'd already switched to the new schemes in development by DePiep and R8R, I'd suggest a darker gray for "discovered but uncharacterised" (like Og) and a lighter gray for "undiscovered" (like E172), but since the current old scheme has a dark gray for the post-transition metals already there simply isn't enough room for two shades of light gray with slightly different brightnesses. Perhaps for now we could have a light off-gray like #d7e8e6 for "discovered but uncharacterised", while repurposing the totally neutral and light gray #e8e8e8 for "undiscovered"? Double sharp (talk) 06:22, 26 April 2018 (UTC)

Double sharp. My thoughts:

That would be adding a second meaning to the background color. That would be confusing, and hard to keep clear/explained. We need a strong case to introduce such an exception, because our standardised legends are a useful asset. (In larger PT's we use the occurrence=border to note the difference, like {{this}}. Which is to the point: undiscovered is an occurrence).

Do we really want to add that info to the micro PT? Of course, being small means showing less information, full stop. IMO, the major point of the micro PT is showing the PT structure in overview, not individual properties. Even more so for an extended PT (location of the g-block, as predicted, is highly interesting & useful).

Yes that is the another-gray problem, well described. If we need that extra color, I'd prefer changing the PTM-gray into off-gray, freeing the white-grays-black for meanings like "unknown". (I am thinking about a speedy urgent colorchange to improve the faults in AM-darkred, PTM-gray, MOID-brown).

The article could also use the |mark=Uue, Ubn, ... parameter adding black borders, as is done for E119 in the article. Would that help? Or, we can add a second mark option, showing a say red or gray border. You want a demo?

Or should we create an other micro PT, dedicated to this topic, having the cells merged into blocks or ranges (no individual cells visible/clickable)?

BTW, do you need the same in {{this PT}}? If so, In there we could add the borders preferably.

- DePiep (talk) 11:49, 27 April 2018 (UTC)

Well, I agree that "undiscovered" is a sort of occurrence, but simultaneously it is a much more important one than any of the others. Pretty much all chemists today would agree that a synthetic element produced in invisibly small quantities should still be placed on the standard periodic table, but that an undiscovered element that has not been produced at all should not. So the boundary between "synthetic" and "undiscovered" is very important in a way that the boundary between "natural" and "synthetic" isn't, because the former and not the latter separates the experimentally known from the experimentally unknown. It is one of the first things I would want to make clear in an illustration of the extended periodic table, that the elements in the extension have not yet been discovered: that is the whole point of it being an extension, to go beyond what is currently known. In a micro and compact periodic table, we cannot do this with borders; all we have is colour, and I think we should at least make use of that. (We can use both the colour and the border when we have the space for it, as in extended periodic table (large version).) I do not think that we should emphasise the undiscovered elements with a border; the discovered elements are more important, since we actually know them, and I would instead mute the undiscovered elements somehow. Double sharp (talk) 12:17, 27 April 2018 (UTC)

Very complicated. Can we, shall we, reduce this topic to: "extended PT" only? - DePiep (talk) 19:50, 27 April 2018 (UTC)

Where should we stop? 130? 172?? 500??? I would vote for removing all undiscovered elements from the tables and stopping at 118, until scientists actually announce the discovery of more. It is all right to have an article on predicted elements at Extended periodic table, but I think including them on tables in other articles is going too far and could actually confuse some non-scientific readers. For similar reasons I would not include Atlantis on maps of the Earth, except in the article on Atlantis. Dirac66 (talk) 20:05, 27 April 2018 (UTC)

No need to "stop" anywhere. From E119 and up, everything is theoretical. But why is that forbidden area? This talk is about "predi[[]]cted" element properties, very to the point. I love the issue. - DePiep (talk) 20:20, 27 April 2018 (UTC)

I do not see anywhere on WP where the undiscovered elements are included unless they are the main topic: extended periodic table, extended periodic table (large version), ununennium, unbinilium, unbiunium. Double sharp (talk) 02:44, 28 April 2018 (UTC)

Yes I understand they could be marked in any extended PT article. But no I maintain that it should not be done by bg color, because that principally is a different theme. "Undiscovered" not on the scale of "occurrence". Also, above discussing removal of "predicted" categories at #Oganesson, this change into basic "unk chem properties" was explicitly noted/warned and agreed. On top of this, "undiscovered element" being secondary to "extension element", in a micro PT that information may be ditched (not signaling "undiscovered"). Double-using the bg-color for this would reintroduce the "predicted" status for category anyway, and in my first reply here I listed four alternative options.

Reading your arguments in detail, Double sharp, some notes. The relative importance between "primordial ... undiscovered" occurrences (4 steps) may vary, but that is less relevant in this (unless one proposes to simplify into a 2-class occurrence). one of the first things I would want to make clear ... extended PT -- Why not start, first and foremost, with make clear what the extension is? Of course today these are the same sets, but that may change tomorrow when a new element is discovered. Even in that situation, I'd expect that the PT shows what the extension is (i.e., all beyond period 7). Whether say E122 is discovered should not confuse that. Following this, mute the undiscovered elements somehow is strange, and reads like contradicting "undiscovered" ... much more important.

I think marking the extension elements somehow (E119 and up) is more to the point. - DePiep (talk) 08:54, 1 May 2018 (UTC)

• See 1st demo. 1st target: show what is the extension. - DePiep (talk) 15:36, 2 May 2018 (UTC)

_form:→Extended periodic table

Hydrogen

Helium

Lithium

Beryllium

Boron

Carbon

Nitrogen

Oxygen

Fluorine

Neon

Sodium

Magnesium

Aluminium

Silicon

Phosphorus

Sulfur

Chlorine

Argon

Potassium

Calcium

Scandium

Titanium

Vanadium

Chromium

Manganese

Iron

Cobalt

Nickel

Copper

Zinc

Gallium

Germanium

Arsenic

Selenium

Bromine

Krypton

Rubidium

Strontium

Yttrium

Zirconium

Niobium

Molybdenum

Technetium

Ruthenium

Rhodium

Palladium

Silver

Cadmium

Indium

Tin

Antimony

Tellurium

Iodine

Xenon

Caesium

Barium

Lanthanum

Cerium

Praseodymium

Neodymium

Promethium

Samarium

Europium

Gadolinium

Terbium

Dysprosium

Holmium

Erbium

Thulium

Ytterbium

Lutetium

Hafnium

Tantalum

Tungsten

Rhenium

Osmium

Iridium

Platinum

Gold

Mercury (element)

Thallium

Lead

Bismuth

Polonium

Astatine

Radon

Francium

Radium

Actinium

Thorium

Protactinium

Uranium

Neptunium

Plutonium

Americium

Curium

Berkelium

Californium

Einsteinium

Fermium

Mendelevium

Nobelium

Lawrencium

Rutherfordium

Dubnium

Seaborgium

Bohrium

Hassium

Meitnerium

Darmstadtium

Roentgenium

Copernicium

Nihonium

Flerovium

Moscovium

Livermorium

Tennessine

Oganesson

Ununennium

Unbinilium

Unquadtrium

Unquadquadium

Unquadpentium

Unquadhexium

Unquadseptium

Unquadoctium

Unquadennium

Unpentnilium

Unpentunium

Unpentbium

Unpenttrium

Unpentquadium

Unpentpentium

Unpenthexium

Unpentseptium

Unpentoctium

Unpentennium

Unhexnilium

Unhexunium

Unhexbium

Unhextrium

Unhexquadium

Unhexpentium

Unhexhexium

Unhexseptium

Unhexoctium

Unhexennium

Unseptnilium

Unseptunium

Unseptbium

Unbiunium

Unbibium

Unbitrium

Unbiquadium

Unbipentium

Unbihexium

Unbiseptium

Unbioctium

Unbiennium

Untrinilium

Untriunium

Untribium

Untritrium

Untriquadium

Untripentium

Untrihexium

Untriseptium

Untrioctium

Untriennium

Unquadnilium

Unquadunium

Unquadbium

Red box: extension (Element 119 and higher)

And I think this is not a good way to go about it. Look at Glenn T. Seaborg's article: it says "he postulated the existence of super-heavy elements in the transactinide and superactinide series", and here is Seaborg's 1970 paper about the extension to show it. Notice that he writes then that "the elements through 103 have been accounted for satisfactorily", that the elements from 104 onwards are all presented as parenthesised atomic numbers in dotted boxes, and that he extends the table all the way to Z = 168. This seems to mean that for Seaborg, elements 104–118 were part of the extension. If they are not now, then that can only be because they have since been discovered. So either the "extension" means "transactinides and onwards" or it means "anything that has not been discovered", and since we obviously no longer consider oganesson part of the extended periodic table, it must be the latter. That means that once element 119 is discovered, it is no longer part of the extension, and therefore what we are really looking at here is "undiscovered" as an occurrence. It is an important occurrence because it indicates that an element is not actually known and hence not actually on periodic tables (not the speculative extended ones, of course), but simultaneously that means that the element it describes is less important as we don't know anything about it; therefore, there is no contradiction. Double sharp (talk) 15:43, 4 May 2018 (UTC)

EN & SEP of nonmetallic elements

@Sandbh:: I think the picture File:EN & SEP of nonmetallic elementsF.png, which appears in Nonmetal § Properties would be better without the dashed lines. If anything, an oval surrounding the metalloids and coencentric ovals surrounding the reactive nonmetals (including H) and the nonmetalic halogens would seem clearer, less arbitrary, and subtly emphasize that the lines are descriptive and not an attempt at being defining. Any thoughts? YBG (talk) 14:20, 14 May 2018 (UTC)

The third bullet point was intended to address this: "The dotted horizontal and vertical guides are intended only to sketch the boundaries of a broad progression in nonmetallic character, from the metalloids towards the lower the left to oxygen and the nonmetallic halogens towards the upper right." The oval around the reactive nonmetals may look awkward if it includes P. The oval around the nonmetallic halogens will look awkward since it would include O, unless I put a dashed circle around it as per H and P. So, not sure I see the advantages outweighing the disads of the current picture. Sandbh (talk) 12:08, 15 May 2018 (UTC)

I guess I fail to see how those dotted line actually shows anything about a broad progression. Upon second thought, I think the chart would be better with no dotted lines, neither the original orthogonal ones nor the ovals I suggested. The notes could be adjusted to something like the following:

• The cluster of elements on the left show that, for the most part, the elements commonly recognized as metalloids are the weakest in both electrode potential and in electronegativity.
• The string of elements in the upper right show that oxygen and the nonmetallic halogens are the strongest oxidising agents, readily forming the anions F^–, Cl^–, Br^–, and I^– and H₂O^– and OH⁻.
• Hydrogen and nitrogen have anomalous standard electrode potential due to their reluctance to form anions H^– and NH₃^– NH₂⁻.

The correlation label would be better as R² = 0.94 <br/>(without H, N); then if desired, add another line marked R² = #.## <br/>(with H, N)

YBG (talk) 16:13, 15 May 2018 (UTC)

I think you mean OH⁻ and NH₂⁻ for O and N respectively. Other than that it is mostly fine, but instead of talking about weak or strong electrode potentials I'd want to speak numerically (large positive, small positive, small negative). Double sharp (talk) 04:46, 16 May 2018 (UTC)

@Double sharp: Thanks! I've fixed the ions; rewording the comparisons will have to wait til later. YBG (talk) 05:01, 16 May 2018 (UTC)

Probing the chemistry of astatine by the proxy of the superatom Al₁₃

Here's an interesting new paper! Double sharp (talk) 15:35, 17 May 2018 (UTC)

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How to proceed with reclassifying nonmetals?

Section header inserted YBG (talk) 00:27, 20 April 2018 (UTC)

• How to proceed? To establish the outcome, I see three routes. We should write a (formal) proposal. Then:

1. RfC

2. Inviting all participants to discuss here (maybe resulting in: "OK, go for an RfC")

3. Discuss here without formal invitation

I would like the strongest result possible, but I fear distractions or re-doing old discussions from the topic when formal RfC.

-DePiep (talk) 09:10, 4 April 2018 (UTC)

I think that a discussion here would be a perfectly strong result for that. We are the relevant Project, after all. Given that, I tend to think of RfC as of a last resort for when a consensus is nowhere to be found or possibly for some extremely important policy-changing decisions (in all honesty, the one in question isn't nearly that important). We should be perfectly fine to have a discussion here. In addition to that, I don't think we need formal invitations; regular invitations should do if anyone wants that at all. Actually, I don't think we need that, either, we are a perfectly capable Project that has in fact already come to a consensus.--R8R (talk) 10:41, 4 April 2018 (UTC)

@Double sharp, YBG, and Sandbh: it would be great to hear your thoughts on the matter before we act.--R8R (talk) 10:59, 15 April 2018 (UTC)

I agree with R8R that a discussion here is sufficient as we are the relevant project. What I'd like most is a formal proposal on what to do (or a proposal to leave the status quo) which we can hammer out and improve until we reach a consensus. We are the most active participants here, but page-watchers and others are free to join in and contribute, as they have in the past. I just need to remind myself to make sure to be as welcoming to less-frequent contributors as I am to those of you I've become wiki-acquainted with over the past few years. YBG (talk) 02:51, 16 April 2018 (UTC)

Proposal (Sandbh)

My formal proposal is to implement the two-category scheme, namely reactive nonmetals, and noble gases. I believe this is what we reached consensus on.

The nonmetal article might partly go like this:

The nonmetals are divided into two categories according to their relative propensity to form chemical compounds. These categories are reactive nonmetals and noble gases. The reactive nonmetals comprise hydrogen (in group 1), carbon, nitrogen, phosphorous, oxygen, sulfur, and selenium (in groups 14–16) and fluorine, chlorine, bromine, and iodine (in group 17). The noble gases are helium, neon, argon, krypton, xenon, and radon (in group 18). For convenience within this article, the four group 17 elements are referred to as "halogen nonmetals".

The reactive nonmetals have a diverse range of individual physical and chemical properties. In periodic table terms they largely occupy a position between the weakly nonmetallic metalloids to the left and the noble gases to the right.

Physically, four are solids, one is a liquid (bromine), and six are gases. Of the solids, carbon, selenium, and iodine are metallic-looking, whereas sulfur has a pale-yellow appearance. Ordinary white phosphorus has a yellowish-white appearance but the black allotrope, which is the most stable form of phosphorus, has a metallic-looking appearance. Bromine is reddish-brown in colour. Of the gases, fluorine and chlorine are coloured pale yellow, and yellowish green. Electrically, most are insulators whereas carbon is a semimetal and black phosphorus, selenium, and iodine are semiconductors.

Chemically, they tend to have moderate to high ionisation energies, electron affinities, and electronegativity values, and be relatively strong oxidising agents. Collectively, the highest values of these properties are found among oxygen and the halogen nonmetals. Manifestations of this status include oxygen's major association with the ubiquitous processes of corrosion and combustion, and the intrinsically corrosive nature of the halogen nonmetals. All five of these nonmetals exhibit a tendency to form predominately ionic compounds with metals whereas the remaining nonmetals tend to form predominately covalent compounds with metals.

The noble gases have very similar properties, all being colorless, odourless, and nonflammable. With their closed valence shells they have feeble interatomic forces of attraction resulting in very low melting and boiling points. That is why they are all gases under standard conditions, even those with atomic masses larger than many normally solid elements.

Chemically, the noble gases have high to very high ionisation energies, negative electron affinities, and moderate to very high electronegativities. Compounds of the noble gases number less than half a thousand, with most of these occurring via oxygen or fluorine combining with either krypton, xenon or radon.

Characteristic and other properties of metalloids, reactive nonmetals, and noble gases are summarised in the following table. Metalloids have been included in light of their generally nonmetallic chemistry. Physical properties are listed in loose order of ease of determination; chemical properties run from general to specific, and then to descriptive. While the table shows the main points of difference it is somewhat arbitrary since exceptions and boundary overlaps can be found within each category. Important instances of such are so noted.

As I said a while back...

"…[the comparative table] looks much better than what I had imagined. You can see the transition in metallic character going across the three columns [inc. the metalloids]. I can see…potential for elaborating, in the article, the trends and patterns occurring in the central [reactive nonmetals] column [since this is where the main focus of day-to-day regular nonmetallic chemistry occurs*]."

* The metalloids have predominately nonmetallic chemistries but I don't count them as being representative of "regular" nonmetallic chemistry (indeed you can see from the first column in the comparative table that they are different to well-behaved nonmetals).

What needs to be done is to redraft a new nonmetal article i.e. update the former draft, and make the associated changes to our tables, and the colour category legend. I recall User:DePiep is already across the colour scheme. Sandbh (talk) 02:58, 18 April 2018 (UTC)

Discussion of proposal

I like this. Double sharp (talk) 03:12, 18 April 2018 (UTC)

re Sandbh: as always, a pleasant and sound reading.

I edited to read "(in groups 14–16)" (not 13 ).

"For convenience within this article, the four group 17 elements are referred to as "halogen nonmetals". Maybe the part I italicised here could be gone? AFAI remember, astatine was in the metalloid-category long time ago, while still accepted as a halogen (=group 17)-member. Our consistent difference between group/column versus category. In other words: not a local article incident, but consistently throughout enwiki, and science-based not an editorial choice. With this, the notion "halogen nonmetals" is a correct Venn-description for the set.

I'm a little sensitive about giving the impression that "halogen nonmetals" is some kind of offically or semi- approved term. I'd like to make it clear that "halogen nonmetals" is not one of our headline terms or categories. It is more like e.g. gaseous nonmetals or refractory metals. Maybe keep for now and delete later on, once we see what sort of reception the new categorisation scheme gets? Sandbh (talk) 04:16, 19 April 2018 (UTC)

I wonder if we could be loose about this and just call fluorine, chlorine, bromine, and iodine "the four nonmetallic halogens" or "the four stable halogens", and then just "halogens" thereafter. When I think about the halogens I usually just think about F, Cl, Br, and I; while I will admit At as one after being alerted to it, I find its status ambiguous, and I don't think I would call Ts a halogen. It feels completely natural to me to ask things like "is astatine a halogen" or "is oganesson a noble gas", which implies that all of these are really categories and that they just act like groups because the elements in the group but not the category are not terribly important. After all, we have a precedent: hydrogen is in group 1 but isn't an alkali metal. Since Fricke is the source for many predictions we give on Ts and Og, it would be interesting to see how he uses the terms "halogen" and "noble gas" in relation to them, and also look up how At is treated in the literature. Double sharp (talk) 05:58, 19 April 2018 (UTC)

Reactive nonmetal will be the legend link.

From the blockquote: What is the "central [reactive nonmetals] column" (15,5 metrically ...)?

That was my clumsy way of referring to the reactive nonmetals column, which is the central column in the comparative table of metalloid--reactive nonmetal--noble gas. Sandbh (talk) 04:04, 19 April 2018 (UTC)

I will be back here about the new singel color (expect a new green). - DePiep (talk) 20:44, 18 April 2018 (UTC)

re Double sharp: As I read it, "halogen" is still not a category name here. (See my note above: a group only, as it was before). - DePiep (talk) 20:44, 18 April 2018 (UTC)

I support this as well.--R8R (talk) 13:30, 19 April 2018 (UTC)

Me too. My comments here are non-blocking. (Can we get a Yeah-vote list though)? - DePiep (talk) 18:08, 19 April 2018 (UTC)

I support this. A couple of comments:

1. If we use "nonmetalic halogens" instead of "halogen nonmetals", it doesn't look like a category name and it doesn't require explanation. So the entire sentence can be struck. For convenience within this article, the four group 17 elements are referred to as "halogen nonmetals."

   Will do. Sandbh (talk) 03:24, 20 April 2018 (UTC)

2. The noble gases have very similar properties is ambiguous - at first I thought it meant "... very similar to the above" instead of "very similar to each other."
3. This whole discussion is very helpful in clarifying the difference between categories (colors) on the one hand and groups (columns) on the other, a distinction that we should attempt to maintain, at least in our own minds, even when we discuss the noble gasses, which constitute not only a category but also a group.

    Two thumbs up! YBG (talk) 00:45, 20 April 2018 (UTC)

Huzzah! Sandbh (talk) 03:20, 20 April 2018 (UTC)

Oganesson

Relocated from the above. Sandbh (talk) 04:24, 19 April 2018 (UTC)

One last thing we ought to do behind the scenes is to sort out the predicted categorisation of oganesson, though. In the above text we are excluding it from the noble gases but including it in group 18. That implies that "noble gas" (and possibly "halogen", with an ambiguous status for astatine if so) are now being treated as category names rather than group names, which I am in favour of. And if we are no longer treating it provisionally as a predicted nonmetal, it seems to me that we need to (hopefully quickly) decide what to call it. Double sharp (talk) 03:12, 18 April 2018 (UTC)

…if the oganesson is a "predicted NG" all is fine, if it is "predicted halogen/metalloid", then indeed the noble gases change/reduce to categoryname only, not a group any more (halogen went the other way around). That is: if it is necessary and OK to add any "predicted ..." to Og. An other outcome could be to leave Og "unk chem properties", grey, and so as yet not changing any noble gases definition. I'ĺl have to wait and see re this. - DePiep (talk) 20:44, 18 April 2018 (UTC)

I'm inclined to leave it as "unk chem properties", grey, unless we have a reliable source predicting it will be a metal. I haven't been able to find any one willing to make a call on this, so far. I do agree with DS that it will probably be a metal but that is speculation on our part, is it not? Sandbh (talk) 04:24, 19 April 2018 (UTC)

Hmm. Is Droog Andrey's periodic chart good enough as a source for oganesson being predicted to be a metal? He is a chemist and it is published, after all. ^_^ Short of that I don't know of any calculations for Og, though emailing the authors for the studies of fcc At and hcp Fl and asking if they might be interested in doing the calculations might work as a long shot. I think uncolouring Og alone makes it look fairly odd and if we are going to do that we should probably stop emphasising all those predictions with colours and revert to grey "unknown chemical properties" for Mt through E172 (except for Cn). Double sharp (talk) 05:49, 19 April 2018 (UTC)

Unless there are reliable sources to the contrary, I agree with Double sharp: revert to grey "unknown chemical properties" for Mt through E172 (except for Cn). Sandbh (talk) 00:14, 20 April 2018 (UTC)

Just to be clear about what I mean by this: I am proposing complete removal and deprecation of "predicted" colours, even on the extended periodic table, as there are now many sources and many disagreements on categorisation for several elements (for some, like E167 through E170, none of them even say anything about metallicity), including for Og (which is already on the non-extended periodic table). So you'd still have E172 under Og, which is under Rn, but neither E172 nor Og would use a lighter version of the noble gas colour anymore. Double sharp (talk) 04:16, 20 April 2018 (UTC)

I concur, especially re the many sources and disagreements. Sandbh (talk) 06:00, 20 April 2018 (UTC)

Seems good to me as well.--R8R (talk) 09:24, 20 April 2018 (UTC)

I'll take care this removal of "predicted"-colors will be listed in #Implementation. - DePiep (talk) 09:11, 21 April 2018 (UTC)

BTW, the Royal Society of Chemistry treats oganesson as a metal on its website, but given that this prediction is likely disputed this does not affect the stand I expressed above. (I would nevertheless be OK with considering Og on the heavy metals article, though.) Double sharp (talk) 09:45, 20 April 2018 (UTC)

Interesting. None of the RSC references for the "Uses and properties" of oganesson support its classification as a metal. The Jefferson Lab ref counts it as a non-metal. The RSC have nothing to say about the status of At, and they count Po as semi-metal whereas one of their cited references (Jefferson Lab, again) counts it as a metal. I wouldn't rely on the RSC table given these inconsistencies. Sandbh (talk) 00:07, 21 April 2018 (UTC)

re Sandbh unless we have a reliable source predicting it will be a metal, above. To consider. Note that even when the prediction is well-sourced, we cannot note that any more in the PT (because there is no category "predicted" any more—at all). The option "predicted" will also disappear from all infoboxes wrt to coloring. So, the category color will be grey in all these cases; any "predicted" claim can be noted verbose only (need to check {{Infobox element}} for this). - DePiep (talk) 11:38, 21 April 2018 (UTC)

The following (predicted-only) categories will disappear completely: eka-superactinide, eka-superactinide (predicted), superactinide, superactinide (predicted). Please check if indeed there is no need for them anywhare in bg colors. - DePiep (talk) 11:54, 21 April 2018 (UTC)

I can't think of anything that would necessitate keeping them around. In the (probably not very near) future when elements 121 and onwards are synthesised and chemically characterised, we can reinstate the superactinide colour. I think the need for verbosity is not a bad thing, considering that the predictions are very varied (is element 164 dvi-platinum, dvi-mercury, dvi-lead, or dvi-radon?). Double sharp (talk) 14:28, 21 April 2018 (UTC)

This seals it. Thanks Double sharp for replying this careful & to the point. Will happen, see #Implementation. - DePiep (talk) 21:33, 21 April 2018 (UTC)

I know we don't need it, but here's one more thing in favor of ditching the predicted colors: The job of prediction is much harder today than it was in yesteryear, what with the effects of relativity. Consequently it is highly likely that predictions of the characteristics of elements will be unclear, and even if it were possible, we would reject out of hand a color scheme capable of representing, say, "30% of sources believe it will prove to be metalic, 5% reactively nonmetalic, and 15% noble gas, with 50% undecided and a margin of error of ±10%." YBG (talk) 22:33, 21 April 2018 (UTC)

Mendeleev did not predict "chemical properties", he predicted "elements" (by atomic numbers). PT core business. - DePiep (talk) 23:06, 21 April 2018 (UTC)

Well, for some of them (Sc, Ga, Ge, and Tc), he not only predicted the elements but some of their chemical properties; there's a table in gallium summarising what he predicted, for instance. Double sharp (talk) 03:52, 22 April 2018 (UTC)

• I assume that this also pertains to a "predicted phase" (state of matter at STP). Today "Phase" can have input "gas (predicted)", which then shows same red as "gas". So, the word could still appear in mainspace. But following this talk, that should be changed to: "phase=unknown". - DePiep (talk) 16:32, 23 April 2018 (UTC)
  • Yes, it should be "phase=unknown". The predictions can of course still appear as text in the element infoboxes (where I'll edit them to be more uncertain, now that they will no longer be tied to colours). Double sharp (talk) 23:28, 23 April 2018 (UTC)
    • P.S. Hmm, is the boiling point of flerovium really predicted? It's calculated for sure, but that is from the experimentally known ΔH_ads. Double sharp (talk) 23:35, 23 April 2018 (UTC)

Article redraft

This can be found here.

It looks ready to me apart from (1) two graphics needing to be updated, as noted in the redraft; and (2) perhaps some prose minutiae which I may get started on next.

I'm very happy with the redraft. I've never seen a single treatment of the nonmetals that brings together so many things namely:

• the relevance of the metalloids
• the examination of the L-R trend in nonmetallic character, including within the reactive nonmetals
• the alternate categorisations
• the prose comparison of the properties of the reactive nonmetals and the noble gases, supplemented by the metalloids in the comparative table
• the group-by-group bios
• the cross-cutting relationships within the reactive nonmetals.

Please let me know how it looks to you. Sandbh (talk) 04:20, 20 April 2018 (UTC)

About the table in #Alternative_categories. The numbered rows now use the colors for polyatomic and diatomic nonmetals (green and yellow). However, there are to be abandoned. My question is: in this table, do you still need these colors/categories? Or is there an other solution? I'd prefer to abandon those colors & their category names; we could invent two new colors for this table. At least green-confusion must be prevented.- DePiep (talk) 14:23, 20 April 2018 (UTC)

Looked again: maybe the noble gas column should be un/recolored too. Here too: the color "Noble gas" (blue) only correct in the top row. The lower rows could be uncolored. For example, the row "solid, liquid, gaseous" should not use category colors. - DePiep (talk) 15:40, 20 April 2018 (UTC)

Colours removed. How does it look now? Sandbh (talk) 00:22, 21 April 2018 (UTC)

The redraft is ready. Thank you @DePiep: for your help. Sandbh (talk) 01:37, 21 April 2018 (UTC)

re using yellow instead of green: see my re at #Implementation. -DePiep (talk) 08:37, 21 April 2018 (UTC)

re "how does it look?" (table #Alternative_categories) No errors showing, but it looks a bit unbalanced don't we think? Some distracting and confusing parts in there. May I suggest:

1. Only use the two colors in the top row (good identification of the two sets).

Done

2. Rows below: no colors, and continue each row full width (no rowspans in the NG column). This more strongly completes each row essence: "Electronegative – Very electronegative – Noble [nonmetal/gas]". IMO repetition (of NG set in rows) not a problem; one is supposed to read the table horizontally. Example of already good: the row solid/liquid/gaseous.

Done

3. To absorb the row 5 "H" more fluently in the table, add an ~empty column to the left (above that H box)?

Not done. I kept H where it is so as to keep the width of the table balanced (with the base scheme label cell in the first row). Sandbh (talk) 03:48, 23 April 2018 (UTC)

About row 5: could it be: "Other[/remaining] nonmetals" here? - DePiep (talk) 08:37, 21 April 2018 (UTC)

Not done. The cited reference simply calls them "nonmetals". Sandbh (talk) 03:48, 23 April 2018 (UTC)

More thoughts on that table: I have added signatures to my original bullets to clarify the threaded discussion. YBG (talk) 14:02, 23 April 2018 (UTC)

• I don't understand "and their kind". It should be replaced with something more understandable - or perhaps eliminated. YBG (talk) 07:18, 22 April 2018 (UTC)

Done. Sandbh (talk) 10:24, 22 April 2018 (UTC)

• The row label "Default scheme" seems weak. Better to leave that cell empty. We can get the concept across by having two table-spanning labels. At the top of the table "Categories of nonmetals", then between the unlabeled row and row "1" a second table-spanning label saying "Alternate categorizations". YBG (talk) 07:18, 22 April 2018 (UTC)

  Alternative action taken. I kept the cell but changed the title, and I changed the the name of the table to Categorisation scheme alternatives. This name encompasses the base scheme plus the other entries. Sandbh (talk) 10:24, 22 April 2018 (UTC)

  This is much better. Another alternative would be to have the title say "Nonmetal categorizations: base scheme and alternatives" (on one line or two) and then the 0th row could be simply labeled "base" - or even remain unlabeled. Without trying this, I'm not sure how it would look, so if you don't like it, feel free to ignore it. YBG (talk) 13:50, 23 April 2018 (UTC)

  Feel free to experiment YBG, and it looks better implement it. Sandbh (talk) 04:59, 25 April 2018 (UTC)

• In row 4, label the NG as "monatomic nonmetal" or better still "monatomic nonmetal <br> noble gas" YBG (talk) 07:18, 22 April 2018 (UTC)

  Not done since "monatomic nonmetal" is a made up category name. Sandbh (talk) 10:24, 22 April 2018 (UTC)

  Point well taken, much though my OCD tendencies cry out to highlight the poly/di/mono paralellism. YBG (talk) 13:50, 23 April 2018 (UTC)

  I disagree with Sandbh on this one: I don't think it's any more made up than "polyatomic nonmetal" and "diatomic nonmetal", and we allude to the monatomicity of the noble gases in the nonmetal article already. Double sharp (talk) 03:45, 25 April 2018 (UTC)

  Mea culpa. I just searched for "monatomic nonmetals" in GB, and it is not a made-up term. I've added "(monatomic nonmetal)" to "Noble gas". Sandbh (talk) 04:53, 25 April 2018 (UTC)

• In rows 1 and 5, use "(other nonmetal)" with parens. Or better stil, use "(unnamed category)" or "(unnamed)" or "(uncategorized)". The parens help indicate that this is not a category name but just a catch-all. YBG (talk) 07:18, 22 April 2018 (UTC)

  Not done. See here, for example. Other nonmetal has the same status as the other categories. Sandbh (talk) 10:24, 22 April 2018 (UTC)

  Not sure about that. Notice that in the PT cited, a convenient column break puts both "Other nonmetal" and "Other metal" appear at the bottom, thus muddying the waters. I could be convinced if you could find a source that clearly listed "Other nonmetal" prior to the ("other":) actually named categories. YBG (talk) 13:50, 23 April 2018 (UTC)

  These authors: Myers RT, Oldham KB & Tocci S 2004, Holt Chemistry, teacher ed., Holt, Rinehart & Winston, Orlando, ISBN 0-03-066463-2, have two-page colour coded table on the inside back cover and last page. Their categories are:

Metals	Nonmetals
Alkali metals	Hydrogen
Alkaine-earth metals	Semiconductors (also known as metalloids)
Transition metals	Other nonmetals
Other metals	Halogens
	Noble gases

• In row 5, break the cell currently labeled "Halogen" into two cells, one for the halogens and one for hydrogen. YBG (talk) 07:18, 22 April 2018 (UTC)

  Not done. I kept the "default scheme" cell but changed it to "base scheme" which I thing is plainer English. This cell and the H cell balance out the table. If I broke the cell currently labelled "Halogen" into two cells this would make for an unduly wide second column. Sandbh (talk) 03:48, 23 April 2018 (UTC)

  I disagree. The current scheme is unbalanced in two ways - the unsightly ear hangling off the bottom left of the table, and the NG column being considerably wider than the other columns. Better than my original suggestion would be to have the three NNNG cells in row 5 together consume the reactive nonmetal space without trying to line up the cell dividers with the cell divider divider above. This would eliminate the unsightly ear. Applying a similar technique to row 5, we could narrow the Liquid cell to consume only half the width of the Halogen cell above and so allow the Gaseous cell to be wider than the NG cells above and below. This would allow the NG column width to be better balanced with the rest of the table. YBG (talk) 13:50, 23 April 2018 (UTC)

  Please go ahead YBG. It won't matter if I make the article go live B4 you're done. Things will catch up. Sandbh (talk) 04:56, 25 April 2018 (UTC)

Overall, I think this chart and the accompanying text is very helpful to the general reader and especially for us who have been discussing these various categorization schemes for -- how long is it now? Anyway, very good work. YBG (talk) 07:18, 22 April 2018 (UTC)

Cool, thank you. Been a long time but we got there. Sandbh (talk) 10:24, 22 April 2018 (UTC)

Are we good to go now?

I presume we are since the article is ready and would be easy to post, but I also know there are knock-on consequences like needing to update the periodic table article, and its templates, and updating the element boxes. Sandbh (talk) 03:58, 23 April 2018 (UTC)

I support launching as soon as all the behind-the-scenes stuff you mention is ready. Double sharp (talk) 04:03, 23 April 2018 (UTC)

Need final choice between the two yellows. Pls publish the Moment of Decision (closing the discussion). -DePiep (talk) 14:00, 23 April 2018 (UTC)

My comments above need not cause any delay, they are very minor. When we're all done, it would be interesting to compare this discussion and decision to the last major one in terms of duration and volume of talk page discussion and number and significance of main space changes. Also, as individuals and as a project we might take a bit of time for introspection, to consider our discussion and deliberation style and think about what we're doing well (to make sure we keep doing it) and what we could do to improve. YBG (talk) 14:09, 23 April 2018 (UTC)

• BTW, what happens with the current GA status? - DePiep (talk) 13:18, 24 April 2018 (UTC)

I say we retain it as we are only editing a current article, not requesting a review of a new article. Sandbh (talk) 04:38, 25 April 2018 (UTC)

Moment of decision

Lighter yellow it is.

I'm currently writing a note for the nonmetal talk page explaining what has happened. When ready I'll update the nonmetal article and post the note. Sandbh (talk) 11:02, 24 April 2018 (UTC)

Proposed note for Nonmetal talk page

Here is what I have so far:

Categorisation scheme update Active members of WikiProject Elements have reached agreement to change the non-metal categorisation scheme from: [polyatomic nonmetal] + [diatomic nonmetal] + [noble gas] to [reactive nonmetal] + [noble gas]. Why change? The categorisation of the nonmetals has been a recurring topic of discussion within WikiProject Elements over many years. The noble gas category is non-controversial. This has always left the question of how to categorise what Steudel (1977, p. 269) referred to as the "rest of the non-metals." While the current categories of polyatomic nonmetal (C, P, S, Se) and diatomic nonmetal (H, N, O, F, Cl, Br, I) are objective, being based on the structural motifs of the elements involved, the literature does not approach the chemistry of the nonmetals in this way. Aside from the noble gases, the literature most commonly deals with nonmetals on a group-by-group basis. Thus, there is [H] + [C] + [N and P] + [O, S, and Se] + the non-metallic halogens [F, Cl, Br, I] noting we categorise At as a metalloid, albeit it has been predicted to be a metal. This is an impractical basis for an element categorisation scheme since it would give us a total of 14 colour categories, including metals, and the metalloids. It looks to us that the most widely accepted and long-standing categorisation of the nonmetals, at least conceptually, is a division into noble gases (an IUPAC-approved term) and, by default, "the rest of the nonmetals". There is no widely agreed terminology for the latter but there is widespread agreement that they share a common attribute of being "reactive" nonmetals, in comparison to the noble gases. For example, the terms less reactive, reactive, typically reactive, more reactive, highly reactive, and most reactive nonmetals are all found in the literature in connection with non-noble nonmetals. We therefore think a division into noble gases, and reactive nonmetals (a complementary and arguably non-controversial term) is a more natural way of categorising the nonmetals. The foundations of nonmetal chemistry rest upon the reactive nonmetals; that some of the noble gases could form compounds was not discovered until 1962, and since that time less than 1,000 such compounds have been synthesised. While the properties of the reactive nonmetals are diverse, the overall contrast with the noble gases is marked. And the reactive nonmetals are regularly distinguished from the elements commonly recognised as metalloids (B, Si, Ge, As, Sb, Te) despite the predominantly non-metallic chemistry of the metalloids. The updated nonmetal article sets out the physical and chemical properties of the reactive nonmetals, and the noble gases, and by way of comparison, the metalloids. We think the transition in non-metallic properties, and the distinctiveness of each category, is well borne out. For reference, the updated article includes a table of alterative nonmetal categorisation schemes found in the literature, none of which have attained widespread use. Wikipedia has used two of these schemes in the past namely (1) other nonmetals, halogens, noble gases; and (2) polyatomic nonmetals, diatomic nonmetals, noble gases, however neither of these have been completely satisfactory or representative of the way the non-noble nonmetals are conceived of in the literature. Summary We have concluded that: categorising the nonmetals as either reactive nonmetals or noble gases is more faithful to literature-based conceptions of nonmetals; and within this framework, the updated article makes better sense of the variety and subtlety of the non-metallic elements (Zuckerman and Nachod 1977, preface) against the backdrop of a left to right progression in non-metallic character.

-- Sandbh (talk) 11:23, 24 April 2018 (UTC)

References

Steudel R 1977, Chemistry of the non-metals: With an introduction to atomic structure and chemical bonding, Walter de Gruyter, Berlin
Zuckerman JJ and Nachod FC 1977, in Steudel.

Implementation

The proposal could be implemented as follows. As always, this is without prejudice (no claim is made on the future outcome).

• Reactive nonmetal should be bluelinked, possibly a redirect.

Blue-linked to the relevant section of the redraft, for the time being. Sandbh (talk) 06:02, 20 April 2018 (UTC) i.e. User:Sandbh/Nonmetal_redraft#Reactive_nonmetal

Also: created Reactive nonmetal, redirects to Nonmetal#Reactive nonmetal now. (Ending up at the right page, which is OK). - DePiep (talk) 15:37, 20 April 2018 (UTC)  Done

New background color for Reactive nonmetals

Useful links:

• {{Periodic table/sandbox}}
• {{Periodic table/blind1}} (new green), {{Periodic table/blind2}} (new yellow): graphs only, no texts
• {{Periodic table (32 columns, micro)/testcases}}
• Contrast checks: User:DePiep/PTCC/newcolors

• Ongoing process: new green has been repolaced in the demos (by some yellow). The tested green colors was: A1FFB4.

• I suggest a new green background color for the category:    Reactive nonmetal → #f0ff8f . Mostly because green is not used in the new category set, and it does not interfere with any red bg (which would be bad for colorblindness). See PT/sandbox and PT/blind1 (a no-text demo, showing visual effects).

However. It appears that green is contrasting bad with the liquid-green font of bromine. Also, there already are nine other such conflicts (bad bg vs. font contrasts). Please see my talkpage#PTCC (PT_category_colors) for more research & discussion on this. (pinged R8R) - DePiep (talk) 12:18, 19 April 2018 (UTC)

• Current colors lightgreen and yellow (   polyatomic nonmetal → #a1ffc3 ,    diatomic nonmetal → #e7ff8f ), and any intermediate example colors used in this long discussions, sandboxes and demos, will be removed from contentspace everywhere. They will not show anywhere anymore (except for archives). The new color (green) is the only one. - DePiep (talk) 12:37, 20 April 2018 (UTC)

When yellow is removed from the colour category palette what is left is rather dull, being comprised of red, grey, brown, and green shades. I am no colour scheme guru but it would be good to have a more visually pleasing scheme. I know some discussions have already been had along these lines and will go back and have a look. Sandbh (talk) 02:03, 21 April 2018 (UTC)

I have changed the light green for reactive nonmetals to yellow, which looks much better in my opinion. Sandbh (talk) 02:48, 21 April 2018 (UTC)

Added    reactive nonmetal2 → #EBFF66  ("2") for discussion and demo purposes. To be sorted out before going live. My thoughts on this will follow. - DePiep (talk) 09:26, 21 April 2018 (UTC)

See the Useful links set in top here: demo's with both colors. - DePiep (talk) 11:19, 21 April 2018 (UTC)

About using new green or new yellow for the Reactive nonmetals (the old, currently used green and yellow will be deprecated; visually they are very similar. The new RGB number will be slightly different though. This way every category has its own identifying color RGB number. Pages that have the old RGB number should be updated).

Looking at the blind demo's of both our regular and micro PT's, one can easily agree that the yellow one is brighter, and less boring: "rather dull, being comprised of red, grey, brown, and green shades" [and blue, DP], as Sandbh writes, "... a more visually pleasing scheme". Agree, but my thoughts are about: is this NNNM topic the way & the route we should/can solve that dullness?

This is why/how I ended up proposing green not yellow (both options become available of course because those two categories are abandoned for one new one).

Attention grabber. As a legend color, yellow has the disadvantages that it stands out always (attention grabber). To use this for a run-of-the-mill category (as reactive nonmetals is), is unbalancing the view. I also remember reading that yellow is a bad usage for webpage elements such as buttons, signals and symbols (cannot link to that now), in this case "buttons" being comparable to "legend items". (Deeper thoughts disclosure: if we would use some yellow in the future, it should be for the metalloids being the important border zone between metals and nonmetals).

White background issue. Also, when yellow is used without border as in our micro PT in infoboxes, contrast with the whitish background is low: e.g. the H-cell is difficult to discern. Note that colors & contrasts may differ between screens, depending on hardware, settings &tcetera. With me, the on-screen contrast is high enough, but checking other computers (including mobile) shows that this is not a guarantee. Add to this that I am quite familiar with the PT ;-) but in general readers are not (they don't know where to expect cells).

To redesign category colors. Of course, the current category pallet is screaming for a redesign (rethink all category=background colors). That should solve the unbalance and dull colors we see today (before and after this Reactive change). Main issues are: used five shades of red (two of them having the same hue even), grey is used as a regular category, brown used (ouch), irregular shading of hues (irregular saturation & lightess; compare the more even block colors), unchecked for colorblindness, unchecked for optimal cell-to-legend linking. Also, the reds for AM and LN are too dark for good contrast (font readability). Point now is that this is not solved by using yellow. Adding yellow does not solve the other color's problems; it is more like overcompensating. Such a redesign is long due, but is a complicated job (basic spread of colors for 9+1 categories, adsjust for colorblindness, work well with other graphics like occurrence/border and SoM/fontcolor). And at this moment: now way this NNNM Reactive change should be delayed because of this issue (changing existing background colors). I'd agree to have this done in 2018, so come PT-150 year 2019 we will have a shiny and invitingly colored PT. R8R is into this too.

My position: given these minor disadvantages of yellow compared to green, I'd prefer green. 'Minor' is to say that none is an absolute blocker. Using yellow to "improve" the dullness & attractivity is overcompensating (adding more extremity on the 'other' side). The other colors keep their issues. Yes the 9+1 category pallet must be redesigned in total that is, but that should be kept apart from this NNNM change. Behind this is a 'promis' and an urgent need to do that full redesign later this year. - DePiep (talk) 11:19, 21 April 2018 (UTC)

I agree that this consensus on categorization should implemented without waiting for the grand recoloring fix. Let's pick what looks best for the present, knowing that whatever deficiencies can be rectified in a future grand recoloring effort. I am personally ambivalent about yellow vs. green - though, full disclosure, I haven't really looked at either one. And I'm thinking right now that maybe I don't want to really look at either one, knowing that better eyes than mine will make a good decision and I don't want my poor color sense get in the way.

I am intrigued by the idea of choosing a color for the metalloids that would highlight them.

Another thought occurs to me, which I mention here so that our resident color expert can consider it and accept or reject it: Might it work to choose two colors per category, a pastel one for backgrounds like in our large PTs and a more intense one for places where we want just a small bright and intense color, like maybe the micro PTs or infobox bullets. Just an idea; I don't really know if it would work or not. No need for discussion here (it really is off-topic). I trust that if there is anything worthwhile to this idea, DP will incorporate it into a future proposal, and if it is not worthwhile, DP will ignore it completely. I will rest that judgement. YBG (talk) 17:36, 21 April 2018 (UTC)

re YBG:

wrt yellow or green for the Reactives now: I accept any preference by Sandbh and Double sharp, even by 1⁄12 of a grain. (Note: yellow will not survive the Redesign: nonmetals will not be yellow in year PT150).

re these colors: don't look away, take another look!

• {{blind-green}}, {{blind-yellow}}; {{Periodic table (32 columns, micro)/testcases}}

Double colors: OT, and noted. - DePiep (talk) 21:56, 21 April 2018 (UTC)

While I like the brightness of yellow, DMacks' comment at User talk:DePiep#Periodic table color in element pages makes me worried that it might not be contrasting enough against the white background in cases where the cells are not bordered (i.e. {{Periodic table (32 columns, micro)}}). In a sense this is a minor issue, though, since we've been having this issue with hydrogen for a while, and we're planning on changing the colours soon anyway. Double sharp (talk) 04:10, 22 April 2018 (UTC)

This is a well considered discussion. I especially like the aim of a new colour palette for the year PT150. Will we ask the editor of e.g. New Scientist to ask readers for their ideas on a new scheme? As an interim solution I favour yellow for the reactives, noting the disadvantages. It is not that different from the existing scheme, which uses yellow for the diatomics. The colour does stand out a bit. This is better, as an interim solution, than the washed out green. There is some poetic resonance here too noting the vast number of compounds contain nonmetals. Sandbh (talk) 04:16, 22 April 2018 (UTC)

DMacks about yellow: [2] (Jan 2016). The quote about yellow being outstanding:

To maintain this sense of similarity importance [between qualitative classes], ensure that hues [colors] maintain similar contrast with the background .. by controlling lightness & saturation of each color. For example, yellow will not be as visible on a white background as red, green, or blue, so the class you assign to yellow may be perceived as having a different importance than the others.

— Cynthia A. Brewer,

Brewer created colorbrewer, on choosing colors for maps. Good source, icw the book.

I don think we need outside New Scientist's ideas for colors. I think WP:ELEMENTS knows best what this category-business is about and actually I've never seen any link or source taking this topic as seriously and comprehensively as we do. Both in science and in coloring. What we need is the on-Wikipedia process of building a new set. The parameters & requirements are well understood by us. BTW I'm working on/in my PTCC.

The next arguments are not optimal: not that different from the existing scheme. "We already use yellow so ...": ouch!?! Since we drop one category (going from 10 to 9), this is the easiest way to get rid of a problematic issue! re better, as an interim solution: since you understand the problem(s) with yellow, then why accept a worse interim solution instead of making a step for the better direction right away? re washed out green: I could make it stronger, but only a bit. It now has lightness & saturation similar to the noble gas's blue, which is easing the eye. re: poetic resonance ... the vast number of compounds contain nonmetals: this is favoring one category over the others. This too is a bad design reasoning. Point is to not make difference between them for secondary, perceived impressions. (Exception: maybe metalloids could have this exception because they inherently are a hinge & border category). In general, all these thoughts & reasonings will be thrown out of the window when we start redesigning the scheme shortly. Task is to eliminate cultural & perceived meanings with colors. - DePiep (talk) 09:36, 23 April 2018 (UTC)

OK, I'm convinced by this to lean in favour of green, noting of coure that I hope that we will usher in 2019 with a new colour set. ^_^ Double sharp (talk) 10:26, 23 April 2018 (UTC)

I like the thought that went into DePiep's post. I agree going from 10 to 9 colours is an opportunity to get rid of a problem. I don't agree if it replaces one problem ("garish" yellow) with another one (a particularly boring colour palette) especially if the whole thing is going to be redesigned for PT 150. That is not what I call taking a step for the better direction right away. I had a look at the green option and I had a look at the yellow option. The second option was easier on my eyes. As well, the green H on top of the red Li was not a good look. Sandbh (talk) 11:14, 23 April 2018 (UTC)

I checked darker colors:

 A  instead of  A 

 A  instead of  A 

Darker green is bad for the "Liquid" color in Br (green on green; a nogo); darker yellow is good for contrast, but is even more attention grabbing IMO. - DePiep (talk) 12:40, 23 April 2018 (UTC)

More color trials. Reuse of demos with two yellows: {{blind1}}, {{blind2}}, {{micro's}}. Notes? ping Sandbh, Double sharp. - DePiep (talk) 13:11, 23 April 2018 (UTC)

The tested green colors was: A1FFB4; now replaced in the demos. - DePiep (talk) 21:00, 23 April 2018 (UTC)

• Per Sandbh's preference, yellow it will be. - DePiep (talk) 13:11, 23 April 2018 (UTC)

Thank you DePiep. Sandbh (talk) 10:56, 24 April 2018 (UTC)

• • OK, no problem: I won't let colour hold us up, especially when I was rather on the fence to begin with. ^_^ I prefer the darker yellow for better contrast, but I'm OK with the lighter one too. Double sharp (talk) 15:30, 23 April 2018 (UTC)

Thank you Double sharp. Sandbh (talk) 10:56, 24 April 2018 (UTC)

I didn't want to overstretch this discussion. This way, it is honoring Sandbh, not agreeing with ;-). - DePiep (talk) 21:00, 23 April 2018 (UTC)

• Once the article is live, I'll sweep the templates. For files: the darker yellow is ebff66. - DePiep (talk) 21:13, 23 April 2018 (UTC)

Prepared in the sandboxes. Waiting for color decision. - DePiep (talk) 09:03, 24 April 2018 (UTC)

Noting DePiep's comment that darker yellow is good for contrast, but is even more attention grabbing; and Double sharp's comment re being fine with either yellow, then lighter yellow it is. Sandbh (talk) 10:58, 24 April 2018 (UTC)

That's #F0FF8F. -DePiep (talk) 13:16, 24 April 2018 (UTC)

References

Remove all "predicted" colors

From the discussion #Oganesson above, it is proposed to remove all "predicted" colors from all our periodic tables, including extended PT's, and use category color "unknown chemical properties" (=light grey). Thisaffects all elements Z=109–172 except for Cn being a post-transition element. Any scientific claim or statement can be addressed in an article's body text.

Demo: see {{Periodic table (32 columns, micro)/testcases}}. Note that {{Infobox ununennium}} (119) will show the same headerbar's color as {{Infobox oganesson}} then (grey). - DePiep (talk) 11:33, 21 April 2018 (UTC)

I agree that it is a good thing to eliminate the predicted colors YBG (talk) 17:24, 21 April 2018 (UTC)

[minor ;-) ]This is about the consequences and implementation. For arguments and !votes please see #Oganesson. - DePiep (talk) 21:29, 21 April 2018 (UTC)

• In {{Infobox element}}: use

|category=unknown chemical properties

|category comment=any text -- will show unedited

Note:

|category=<blank> also will show light-grey headerbars (unk chem properties), and no colored box for "element category"; better use |category comment= with this. - DePiep (talk) 13:32, 23 April 2018 (UTC)

Prepared in the sandboxes. Waiting for color decision. - DePiep (talk) 09:03, 24 April 2018 (UTC)

This removal is not related to the introduction of category Reactive nonmetals, but will be introduced in the same single colorset change (BTW, these are first changes to the 2013 set since 2013). - DePiep (talk) 07:46, 25 April 2018 (UTC)

Refine SoM colors

The SoM fontcolors will be slightly adjusted to improve readability (contrasts). This is unrelated to the Reactive category introduction, but I mention it here because it changes the 2013 color set (in the same update we prepared). More here. - DePiep (talk) 07:46, 25 April 2018 (UTC)

Articles, templates

• In the 11 element infoboxes, change into:

|category=reactive nonmetal.

• Texts: check for "diatomic" and "polyatomic", maybe adjustment needed. - DePiep (talk) 13:57, 23 April 2018 (UTC)

• Templates having the "predicted" legend added:

{{extended, Fricke}}

{{Nefedov, large cells}}

Todo

1. in template page: rm option |predictedN=yes from legend; also |sa= and |eka-sa= (superactinides).

2. in template: replace all "... (predicted)" categories with "unknown checmial properties" for the elements (all element cell input).

3. In any article that uses the template: check text for "predicted" etc.

Prepared in the sandboxes. Waiting for color decision. - DePiep (talk) 09:03, 24 April 2018 (UTC)

Articles to check for "predicted":

• Unbinilium
• Ununennium
• Extended periodic table
• Extended periodic table (large version)
• Unbiunium

-DePiep (talk) 20:53, 23 April 2018 (UTC)

Gone live

I've updated the nonmetal article and added the note to the talk page. Sandbh (talk) 11:40, 25 April 2018 (UTC)

@DePiep, Double sharp, R8R, and YBG: as above. Sandbh (talk) 11:47, 25 April 2018 (UTC)

I thank and compliment you all. - DePiep (talk) 15:08, 25 April 2018 (UTC)

I call: Progression

• Discussion 2012-2013, Categorisation:

Talk opened 2012-06-26

Talk concluded 2013-08-17

Open: 417 days.

• Discussion 2017-2018, Reclassifying the nonmetals:

Talk opened 2017-03-12

Talk concluded 2018-04-25

Open: 409 days.

- DePiep (talk) 15:08, 25 April 2018 (UTC)

After-decision remarks

Any remarks made after the decision better go here. - DePiep (talk) 20:45, 25 April 2018 (UTC)

I thank you for finally reaching the conclusion I had pushed for some months ago. I have updated the periodic table by article quality to reflect the new scheme; I'm now taking courses towards a mathematics degree at the National University of Singapore. It's a little pity that I couldn't devote time to Wikipedia any longer, but now I have more opportunities ahead. Parcly Taxel 04:41, 26 April 2018 (UTC)

I believe I was also an early adapter of this proposal (or maybe I just wish I had been:). Consensus at WP and in this project often takes quite a while to accomplish, and it is worth it to accomplish the end result. And I might add, the end result is not just a decision, and not just a good decision, but a good decision that has broad support and is likely to last for quite a while. YBG (talk) 05:05, 26 April 2018 (UTC)

I recall @R8R: was an early advocate for this categorisation scheme whereas I preferred a tripartite scheme. I am pleased to say the end result is the richer for our exchange of views, and contributions from WikiProject Elements members (active and inactive), and other editors. Sandbh (talk) 07:12, 26 April 2018 (UTC)

• PT images to update: please list files (images) that should be updated. - DePiep (talk) 13:09, 27 April 2018 (UTC)
• I must say, reducing the number of categories (from 10 to 9) makes the overall PT look (the "glancing view") much more at ease! More so because the reduction is in the chaotic (category-spoken) p-block. IMO this is not just an aesthetic aspect, but also an editorial one: how much detail do we want to put in there? (Compare, in extremis: think what happens when give each element its own color). - DePiep (talk) 18:49, 3 May 2018 (UTC)

I've made a couple of changes visible at WP:WikiProject Elements/Articles/Periodic Table by Quality/Other PTQs, specfically, changes to {{Periodic table by article importance}} and {{Periodic table by article work needed}}, basically saying that reactive nonmetal is mid-importance with a high need for work. Feel free to modify. YBG (talk) 05:39, 11 May 2018 (UTC)

• • These periodic table images need an update (from History of the periodic table): File:Periodic_table_compilation.svg and File:Periodic table large.svg. They are outdated, enwiki-wise, since 2013. - DePiep (talk) 09:07, 30 May 2018 (UTC)

@DePiep: Looking through commons:Category:SVG periodic table, here's a bunch more using the old diatomic/polyatomic color scheme:

• 
  Ptable.svg
• 
  Sc-TableImage.svg
• 
  Si-TableImage.svg
• 
  Periyodik tablo tr.svg
• 
  Simple Periodic Table Chart-condensed.svg
• 
  ADOMAH periodic table - electron orbitals (polyatomic).svg
• 
  Periodic table overview (18-columns, group 3 = Sc-Y-Lu-Lr).svg
• 
  * Periodic table (polyatomic).svg *Periodic table (polyatomic)-*.svg

  * * = * id * sr * sr-lat
• 
  * Periodic table.svg * Periodic table *.svg

  * * = * fa * fi * mk * nb * pl * pt * ru * sl * zh-hans * zh-hk * zh-tw * lv
• 
  * Periodic table simple *.svg

  * * = * af * ca * cs * de * el * en * eo * et * fi * fr * hu * it * nl * no * pl * pt * pt-br * ru * sv * uk

— YBG (talk) 09:39, 7 June 2018 (UTC)

The first few are actually so old that they still use the other nonmetal / halogen scheme. Nonetheless, we don't (or at least shouldn't) use most of those images anymore, and if other-language Wikipedias and other sister projects are using them, it is their decision whether to adopt the en.wp colour scheme, not ours. (This remark of course doesn't apply to images that we actually do use, which should be updated.) Double sharp (talk) 10:50, 7 June 2018 (UTC)

File:Il sistema periodico.svg (Primo Levi). -DePiep (talk) 00:50, 28 June 2018 (UTC)