Talk:List of aqueous ions by element

Consensuses currently active or not yet archived:

• § Mini-RfC: What is the best way to show oxidation states within each element?
• § Mini-RfC: Row headers
• § Mini-RfC: Oxidation number format
• § Mini-RFC: Sorting

Please consider !voting on these!

Archived consensuses

1. Use oxy- not oxo-: By WP:COMMONNAME and article names oxyanion and oxycation, should use oxy- instead of oxo-. Article has since relatively consistently used "oxy-". Archive 1 § Oxo- vs oxy-
2. Use templates for formulas: Do not use super/subscripts, but instead use {{chem2}}. Archive 1 § Template:Chem—please use this and not sub- and super-scripts
3. PT cell borders: Display the periodic table with white borders around each element cell. Archive 1 §§ Mini-RFC 1: Cell borders, Evaluation, and Summary
4. PT dividing lines: Do not include the dashed lines demarcating various groups. Archive 1 §§ Mini-RFC 2: Dashed line, Dashed line evaluation, and Summary
5. Include oxidation states in all cases, even when an element has only one. Archive 1 §§ Conclusions re "Table changes"​ and Oxidation numbers
6. Left align formula columns. Archive 1 § Conclusions re "Table changes"
7. Include anions in the main list Archive 1 § Separating anions

Index of talk page & archives by element

2&c Noble gases in archive 1 § Noble gases 8 Oxygen (unarchived) in § Hydroxide OH− ion 16 Sulfur (unarchived) in § Sulfide anion in aqueous solution 17 Chlorine (unarchived) in § RFC: Unstable perchlorate anion 23 Vanadium (unarchived) in § A few comments, based on Richens 24 Chromium (unarchived) in § Color of Cr3+ 36 Krypton in archive 1 § Krypton 43 Technetium in archive 1 § Technetium cations? 43 Technetium (unarchived) in § Radioactive elements 57-71 Lanthanoids (unarchived) in § A few comments, based on Richens 61 Promethium (unarchived) in § Radioactive elements 72 Hafnium in archive 1 § Hafnium 72 Hafnium (unarchived) in § A few comments, based on Richens 78 Platinum in archive 1 § Platinum 81 Thallium in archive 1 § Thallium oxyanions?a 84 Polonium (unarchived) in § Polonium 84 Polonium (unarchived) in § Radioactive elements 85 Astatine in archive 1 § Negative oxidation states 85 Astatine (unarchived) in § Astatine (aq) 86 Radon in archive 1 § Article name change 87 Francium (unarchived) in § Radioactive elements 91 Protactinium (unarchived) in § Radioactive elements 92 Uranium in archive 1 § Uranium 95-103 Heavier actinoids (unarchived) in § Radioactive elements 101 Mendelevium in archive 1 § Metal ions in aqueous solution Note: Includes reference to external source 104+ Transactinides in archive 1 § Metal ions in aqueous solution Note: Includes reference to external source If I have missed any, feel free to add them. YBG (talk) 06:18, 2 October 2021 (UTC)

Sulfide anion in aqueous solution

It does not exist.

That said, probably worthy of a footnote given that it was generally believed to exist until recently (2018). Double sharp (talk) 12:55, 28 July 2021 (UTC)

The phrase "S^2- does not exist in aqueous solution" may be used in common parlance. In actuality, the concentration of sulphide ions is too low to be measured. With "insoluble" divalent metal sulphides, the upper limit for the concentration of sulphide in solution is numerically equal to the square root of the solubility product. See also sulphide in qualitative inorganic analysis for pH dependence of solubility. Petergans (talk) 16:39, 28 July 2021 (UTC)

Personally it does not matter either way whether any particular aquo-ion does or does not exist, as long as there is literature support. S&P show the sulfide anion at pH ca. 13. Their wording accompanying the predominance diagram is interesting as they say it shows, "the properties of the major sulfur species [italics added] pertinent to aqueous chemistry" and that, "other species [which they list in a separate table] are thermodynamically unstable with regard to these." p. 228). The sufide anion article has been cited about 40 times without any naysayers. The sulfide anion will be removed from the image and table. Thanks Double sharp for the detective work, and Petergans for the commentary. @Petergans:, will this be OK? Sandbh (talk) 05:26, 29 July 2021 (UTC)

@Petergans, Sandbh, and Double sharp: Are there outstanding issues here? Is this section ready to be archived? YBG (talk) 22:28, 22 August 2021 (UTC)

There is an o/s here. Sandbh (talk) 05:58, 26 August 2021 (UTC)

@Sandbh: Could you clarify what the outstanding issue is to facilitate moving the discussion forward? 06:39, 26 August 2021 (UTC)

Outstanding: Whether or not some reference to the sulfide anion (aq) is included. Sandbh (talk) 07:47, 26 August 2021 (UTC)

Hydroxide OH⁻ ion

I'm not sure this is an oxyanion.

I suspect that, for H, it's just an anion. As well for O, it's just an anion. Sandbh (talk) 06:44, 1 August 2021 (UTC)

I'd say that for O it's an anion, analogous to SH⁻ or SeH⁻, but for H it's an oxyanion, analogous to OF⁻ and OCl⁻. Double sharp (talk) 06:47, 1 August 2021 (UTC)

That's quick! I moved OH− into the anion column for both H and O, pending further comments. It makes H appear to fit in better; O too. I did see something about a convention of not treating OH− as an oxyanion. Will look some more. Petergans? Sandbh (talk) 06:59, 1 August 2021 (UTC)

Judging by Google Scholar and Google Ngram, it seems that OH⁻ is the "hydroxide anion", rather than the "hydroxide oxyanion". Sandbh (talk) 07:10, 1 August 2021 (UTC)

Wulfsberg, Foundations of Inorganic Chemistry, p. 123: "Oxo anions, MO^y−
_x, which can be assembled from Lewis acids plus smaller numbers of oxide ions, O²⁻
, as Lewis bases..." It seems to me that hydroxide fits this definition about as well as hypochlorite does, if you come at it from the perspective of treating H as the main element that you're adding oxo groups to. However, if you come at OH⁻ from the perspective of treating O as the main element, then it is no more an oxo anion than SH⁻ is. So I would favour treating it the way I suggested above. Richens, FWIW, calls it an oxo anion when talking about hydrogen (p. 123). Double sharp (talk) 07:41, 1 August 2021 (UTC)

Oxford Dictionary of Biochemistry and Molecular Biology - Page 478:

”Oxoanion—any of the possible anions formable from a molecule of an oxoacid…”

From wp:

"An oxyacid, oxoacid, or ternary acid is an acid that contains oxygen. Specifically, it is a compound that contains hydrogen, oxygen, and at least one other element, with at least one hydrogen atom bonded to oxygen that can dissociate to produce the H+ cation and the anion of the acid.[1]”

Water is not an oxoacid, is it? Sandbh (talk) 11:33, 1 August 2021 (UTC)

Water is an acid containing oxygen, as it can donate protons to bases and form OH⁻. So, yes, it is technically an oxoacid. :) Double sharp (talk) 11:42, 1 August 2021 (UTC)

Hmm. Yet water does not meet the definition of an oxoacid? Sandbh (talk) 12:31, 1 August 2021 (UTC)

The requirement for containing another element is not universal, see this for example. In any case, definitions requiring "another element" are obviously not meant for this degenerate case. :) Double sharp (talk) 14:13, 1 August 2021 (UTC)

The wp definition quoted above is from the IUPAC Gold Book, which ought to hold sway over various general dictionary definitions. Sandbh (talk) 01:29, 2 August 2021 (UTC)

Lidin (1996), in Inorganic Substances Handbook, places the hydrogen peroxide ion HO⁻
₂ in the hydrogen section of his book, and notes it is stable in alkaline media. The hydroxide ion OH⁻
is in the oxygen section. Sandbh (talk) 12:31, 1 August 2021 (UTC)

I've now removed the hydrogen peroxide ion since it requires the presence of other species in order to attain the highly alkaline conditions. The H box will thus become red. Sandbh (talk) 01:05, 2 August 2021 (UTC)

@Sandbh and Double sharp: It looks to me like there are no outstanding issues in this section and it is ready to be archived. I plan to archive it in a few days unless someone tells me it should not be. YBG (talk) 22:38, 22 August 2021 (UTC)

This one is outstanding. Sandbh (talk) 06:02, 26 August 2021 (UTC)

@Sandbh: Could you clarify what the outstanding issue is to facilitate moving the discussion forward? YBG (talk) 06:43, 26 August 2021 (UTC)

Outstanding: The status of the hydroxide ion needs to be resolved. Sandbh (talk) 07:45, 26 August 2021 (UTC)

Bubble commentary

This section title did not make much sense to me until I looked very closely at the revised graphic with the circled letters. I suggest that instead the graphic be revised to use circled numbers instead; these can then be used in the notes using these characters: ①, ②, ③, and so on. Circled numbers are available all the way up to ⑳. If one did this, then the section could simply be titled "Notes" and the connection between the diagram and the notes would be self-explanatory. YBG (talk) 23:28, 5 August 2021 (UTC)

Ⓐ Will circled letters do? I wanted to avoid adding more numbers than there already are. I admit to being influenced by the use of COVID free travel zones e.g. there used to be a travel "bubble" covering the east coast of Australia and New Zealand, so that you could travel between the two without needing to go into quarantine. Sandbh (talk) 06:12, 6 August 2021 (UTC)

Even better. I didn't know they existed. YBG (talk) 00:42, 7 August 2021 (UTC)

Thank you for fixing this. It now makes visual sense. However, my overall impression with this section is that it consists of a random collection of factoids with no overarching narrative to help the reader make sense of it. If this were a WP:BLP or WP:LIT article, I reckon that many of the entries would be excised as WP:TRIVIA. When I read the section, I find that many of these bullet points require a fair amount of study before I can figure out what the point is. Then when I finish the section, all I am left with is the vague idea that I have read a random list of factoids. Certainly we must do better, especially if there is any hope of it becoming a featured list. YBG (talk) 01:32, 7 August 2021 (UTC)

A welcome insight. Speaking as someone with a fair appreciation of the chemistry of the elements, and periodic patterns, those factoids mean a lot to me, and explain much about what is going about the PT. Since this is a list rather than an article I thought it was appropriate to present them in list form. I'll see if I can add a contextual narrative. Sandbh (talk)

I am not opposed to this being a list, I just think that this list is too long to digest. Perhaps group the notes into three or four separate lists and introduce each sub-list with a one-sentence paragraph. In this case I think the magic number is much less than the normal 7±2; I think 3±1 would be a reasonable goal for each sub-list. When you frame these notes, think of your audience as someone who has vague but positive recollections of secondary school chemistry. That will significantly increase the potential audience for what might otherwise be a niche technical article. YBG (talk) 05:16, 7 August 2021 (UTC)

If I may suggest one more bubble, I think there should be one about the most radioactive elements being hard to study, and therefore noting that the species that are known may not represent the whole of what is possible, and the identifications may sometimes be in doubt. This would at once clarify some periodic oddities (Lr should have some hydrolysed species like LrOH²⁺, based on its congeners, but for obvious reasons we haven't seen it) and subsume the current long footnote about astatine. Double sharp (talk) 04:39, 7 August 2021 (UTC)

Very good; will do. Sandbh (talk) 05:13, 7 August 2021 (UTC)

As I was preparing to reword these notes so that they would not require the bubble letters, I found all of these factoids fascinating. However, several of them make no mention of ion species at all (B,F,G,I,J) and so hardly seem relevant to an article named List of aqueous ions by element. Furthermore, three of these notes - (A) re hydrogen, (D) re rare earths, and (E) re radioactive elements - are at best only marginally related to the periodic table, and so don't really seem relevant notes to a section named § Periodic table distribution. All in all, most of these notes seem to focus on the distinction between metals and nonmetals. This leaves notes (C), (H), (K), and (L), which can be summarized briefly as positive on the left, negative on the right, and mixed in the middle. YBG (talk) 05:51, 5 September 2021 (UTC)

Notes without bubbles

Here are some notes that I think will describe many of the current PT notes without making use of bubbles. I have included parenthetical labels for ease of reference if someone wishes to comment here.

• (L) The left side of the periodic table is dominated by elements with only positive aqueous ions, shown with solid reddish or orangish cells. This includes all of group 1 and most of group 2 and most of the lanthanides and actinides.
  • (L1) Elements which form simple cations can be found in all groups except 16 through 18.
  • (L2) Elements which form simple cations and no other aqueous ions include all of group 1, the heavier lanthanides and actinides, and lutetium and lawrencium in group 3.
• (R) The right side of the periodic table is dominated by elements with only negative aqueous ions, shown with solid blueish or purplish cells. This includes the early periods of groups 14 through 17.
  • (R1) Elements which form simple cations can be found only in groups 15, 16, and 17.
  • (R2) Elements which form simple cations and no other aqueous ions include only oxygen and fluorine, the first elements in groups 16 and 17 respectively.
• (C) The center of the periodic table is dominated by elements with both positive and negative ions, shown with solid yellow or diagonally split cells. This includes groups 4 through 12.
  • (C1) However, a block of six negative-ion-only elements appear in groups 5 through 8, far from the right side of the table where all other negative-ion-only elements are found.
  • (C2) Likewise, two adjacent positive-ion-only elements appear in groups 9 and 10, far from the left side of the table where all other positive-ion-only elements are found.
• (N) The rightmost column and bottom row are dominated by elements with no known aqueous ion species, shown with colorless cells.
  • (N1) The noble gases (group 18) are generally reticent to react chemically at all.
  • (N2) The radioactive elements from rutherfordium (element 104) up, are difficult to study chemically due to short half-lives and the difficulty of obtaining macroscopic specimens.

Thoughts? YBG (talk) 02:15, 7 September 2021 (UTC)

Outstanding: Sandbh (talk) 01:56, 16 September 2021 (UTC)

RFC: Unstable perchlorate anion

@Petergans, Double sharp, and YBG: The perchlorate anion is not stable in aqueous solution. What are your thoughts on whether or not to include it?

S&P (p. 248) offer the following comments:

"The species which have been entered into the construction of the diagram are Cl2, HCl, Cl−, HClO, ClO−, HClO2−, Cl02, HClO3, ClO3−, HClO4, HClO4—, and H+. It will be noted that the final diagram includes only Cl−, C12, and Cl04−. This indicates that all the other species are thermodynamically unstable with respect to the remaining three. However, all the missing species are very slow to react which means that they can exist temporarily in HOH solutions."

In their list of chlorine species, they rate the perchlorate ion as "Slow decomp".

Since the article's scope is limited to stable ions, this concerns me.

For example, Wulfsberg, shows predominance diagrams for stable forms of the elements at ph 0. He also includes "selected" forms of unstable (metastable) in shaded boxes, for "certain" elements—about 30 in all.

I'm concerned about about being on the edge of a slippery slope. I don't want to be in a situation of making calls about which species are unstable (metastable) and which to include, which is why the lede refers only to stable forms of ions.

Having said that, Wulfsberg includes Cl− and ClO4− ! Sandbh (talk) 07:31, 7 August 2021 (UTC)

I don't see the issue with the chlorine ions, since the decomposition is so very slow at standard conditions (citation: household bleach). I'd prefer to just keep them (yes, including very slow-to-decompose ClO₃⁻), perhaps putting them in brackets to note that while they do persist and "might as well be stable" for most uses, they are not thermodynamically stable.

Anyway, aren't the most serious such cases just S and Cl? Double sharp (talk) 07:37, 7 August 2021 (UTC)

Looking around the literature, the supposed unstable nature of the perchlorate ion is overstated. OTOH there is no doubting the others are unstable. One of books I found referred to a ~70% perchloric acid solution being stable for 25 years. Another book referred to the chlorate ion being stable for seconds in acid solution, and from ten to twenty minutes, to many hours at pH 7. So I think keep perchlorate and add a note about the unstable nature of chlorate, and the others, along the lines of your suggestion. Sandbh (talk) 10:37, 7 August 2021 (UTC)

• No opinion at least for now. YBG (talk) 19:26, 7 August 2021 (UTC)

I've added a corresponding note to the Cl row. Sandbh (talk) 02:23, 8 August 2021 (UTC)

@Petergans, Double sharp, and Sandbh: Seems to me that these unstable ions should be removed from the table and the note changed to read "Additional unstable ions also exist: ClO⁻ , ClO−2 and ClO−3" with the same reference. What think you folks? If you agree, are there other unstable ions that fall in this same category? YBG (talk) 23:05, 22 August 2021 (UTC)

Agree. Not as far as I'm currently aware. Sandbh (talk) 06:08, 26 August 2021 (UTC)

Disagree, because their decomposition is so slow. (Otherwise, one wonders how bleach can be kept and sold.) IIRC this phenomenon also affects sulfur. Double sharp (talk) 15:11, 29 August 2021 (UTC)

Clarify. I think unstable ions should not be included, but I agree with Double sharp that slow decomposition should be no bar. Something that decomposes in a matter of seconds probably should be excluded; ions decomposing in months or years should be included; what would be a reasonable dividing line? Ideally something with a clear gap above and below. YBG (talk) 16:11, 30 August 2021 (UTC)

Outstanding: Sandbh (talk) 01:57, 16 September 2021 (UTC)

Protonated forms of oxo-anions are not shown?

• What is a protonated form of oxo-anion?
• Examples?
• What's the basis for excluding then?

Sandbh (talk) 04:10, 8 August 2021 (UTC)

Would imagine it means something like HCO₃⁻ or HSO₄⁻. Double sharp (talk) 04:40, 8 August 2021 (UTC)

If they show as being stable on a predominance diagram then surely they'd be included? Sandbh (talk) 07:45, 8 August 2021 (UTC)

Frex HTeO3⁻ is there. Sandbh (talk) 07:49, 8 August 2021 (UTC)

I kind of think that, if we're going around including all those obvious deprotonated hydrolysis products of cations, then protonated oxyanions should be there too. Double sharp (talk) 10:03, 8 August 2021 (UTC)

When a protonated oxyanion exists, does the non-protonated oxyanion also exist? If the non-protonated oxyanion exists, does the protonated oxyanion also exist? If either or both of these are always true or even usually true, perhaps we could add a note that would allow the reader to infer the unlisted protonated form from the listed non-protonated form. On the other hand, if such a note becomes overly complicated in order to be accurate, maybe it would be easier to just include the protonated forms in the list.

But if we use the term "protonated" we should at least wikilink it to protonated and possibly explain it.

YBG (talk) 01:05, 9 August 2021 (UTC)

@YBG: Answer to your question: usually yes, but sometimes no (e.g. perxenates xenates).

I kind of think that it would work, except that for similar consistency one could argue the same for deprotonating cations, e.g. turning Ca²⁺ to CaOH⁺. But that would give blanks in the table where there really is a species, although a trivial one... Double sharp (talk) 04:04, 9 August 2021 (UTC)

@Double sharp: OK, so if I understand the situation correctly, adding protonated ions would not increase the number of cells filled in but would nearly double the height of many cells. On that basis, why not add a note to the column header saying that the protonated species also exist for most entries in this column (with an example or two so the naive reader could figure out the pattern, and then list some of the exceptions, all of them if the list is not too long. On the other hand, if we had separate columns for oxyanions and hydroxyanions, I would strongly support their inclusion, both because it would fill in an otherwise empty cell and would not increase the overall size of the table. YBG (talk) 05:56, 9 August 2021 (UTC)

@Double sharp, Sandbh, and Petergans: Seems like we need to add a note someplace. If none of you do so, I may give it a try. YBG (talk) 23:10, 22 August 2021 (UTC)

Outstanding: Sandbh (talk) 06:10, 26 August 2021 (UTC)

Colors

The list shows colors for some ions and not for others. What are we to infer when a color is not shown? That it is colorless? Or that it is not known or not sourced? I suggest that the "clear" or "colorless" be added to ions when the RS so indicates and that ions displaying chromism be labeled as "halotropic", "phototropic", "thermotropic", or the like, with an {{efn}} describing the particular chromic behavior. Then the paragraph before the list can include something like this:

Characteristic coloration of the ions is included where found in the sources.

YBG (talk) 04:28, 13 August 2021 (UTC)

The only response to this has been Petergans' removal of the colors and their subsequent restoration by me with Sandbh's agreement. Somewhere I though I'd read a comment that indicated that the colors had been included where given in the source, but I can't find that comment now, so I may have been imagining that. To the best of my knowledge, no one has reacted to my idea of including notes like "Xxx is halochromic exhibing color1 below pH X and color2 above". Thoughts? YBG (talk) 23:33, 22 August 2021 (UTC)

Oppose. Stick with what the (multiple) sources say, none of which AFAIK, make qualifications based on pH etc. Sandbh (talk) 06:12, 26 August 2021 (UTC)

@Sandbh: So if I understand correctly, none of the sources you consult have mentioned chromism, right?

And I presume that if they had made such a mention, you would have added a note describing this, right?

YBG (talk) 20:58, 26 August 2021 (UTC)

Right; right. Aside from pH indicators, I can't recall mention of the phenomenon of polychromism for the elements in aq solution in my time here at wp, and before that. Peter is of course welcome to provide RS referring this phenomenon. Sandbh (talk) 08:13, 28 August 2021 (UTC)

The problem, I suspect, is that as pH increases the ions will tend to hydrolyse. Fe³⁺ ion has very different and fainter colour (pale lilac) to its hydrolysed forms FeOH²⁺, Fe(OH)₂⁺ (orange, yellow). So, in practice you are unlikely to see Fe³⁺ as violet (it will be drowned out by its own hydrolysis products), especially because it hydrolyses quite readily for pH above 0. Double sharp (talk) 15:16, 29 August 2021 (UTC)

​That may be so. Yet somebody presumably experimentally confirmed that Fe³⁺ is violet, which has since made it into RS. Sandbh (talk) 07:43, 30 August 2021 (UTC)

And so did the ready hydrolysis. As I also wrote of in Iron#Solution chemistry. Double sharp (talk) 07:53, 30 August 2021 (UTC)

Outstanding: Sandbh (talk) 01:58, 16 September 2021 (UTC)

Main related articles

It happens to be that these are the main links:

• Cation => R to Ion § Anions and cations
• Oxycation -- a stub only
• hydroxycations
• Anion => R to Ion § Anions and cations
• Oxyanion -- full blown article
• hydroxyanions

To check out:

Category:Cations (66)

Category:Oxycations (20)

Category:Anions (107)

Category:Oxyanions (48)

-DePiep (talk) 16:29; 18 August 2021 (UTC), 16:33, 18 August 2021 (UTC)~

@DePiep: Not sure if there is anything to do here. YBG (talk) 23:44, 22 August 2021 (UTC)

Nothing to do indeed. Unless someone finds an anomaly in a category, or someone thinks that Oxycation should have content. -DePiep (talk) 11:07, 23 August 2021 (UTC)

Can be kept here not in archive, could be useful for future researching editors. -DePiep (talk) 20:21, 23 August 2021 (UTC)

OK, I won't archive this section for now. YBG (talk) 06:57, 26 August 2021 (UTC)

A few comments, based on Richens

• Lanthanoids. Richens (p. 187) writes The pattern of hydrolysis of Y³⁺ (aq) and the Ln³⁺ (aq) ions appears to parallel that of Sc³⁺ (aq) in so far as the available hydrolysis data are consistent with the formation of the species MOH²⁺ (aq), M₂(OH)4+2 (aq) and M₃(OH)4+5 (aq). ... As in the case of scandium, the lanthanide trihydroxides are only weakly amphoteric but dissolve in excess base proportional to the [OH⁻], giving evidence for the formation of Ln(OH)−4 (aq). So, it seems that the species listed for scandium and yttrium in the table should be repeated for all lanthanoids.
• Hafnium. Should give the same tetrameric species as zirconium, per Richens p. 218.
• Vanadium. V^III dimerises during hydrolysis (Richens p. 232), so the next species after VOH²⁺ should be V₂(OH)4+2 actually. Similarly V^IV hydrolyses (p. 237) to give VOOH⁺, (VO)₂(OH)2+2, and thence to anions like (VO)₂(OH)−5.

I'll continue this when I have some more time. :) Double sharp (talk) 04:20, 24 August 2021 (UTC)

All very good, provided they're experimentally verified and unambiguously characterized. YBG (talk) 04:24, 24 August 2021 (UTC)

I had gone through both Richens and B&M, element by element. There are serious doubts surrounding all polynuclear species. Their structures are [conjectural] based on what is known about solid state structures; there is little or no experimental evidence for the stoichiometry in solution. The situation arises as a consequence of the fact that the pH range between the onset of hydrolysis of the metal ion in solution and formation of a precipitate is very narrow. See, for example the speciation diagram in aluminium#Inorganic compounds. Petergans (talk) 11:14, 24 August 2021 (UTC)

It's not a doubt that Richens seems to have for at least vanadium(IV), but I can try to find B&M to check against, and in the meantime list only the mononuclear ones that seem to be missing (e.g. TcO−4, ReO−4). (I guess Ln(OH)−4 may be doubted as a hydrolysis product.) Double sharp (talk) 11:56, 24 August 2021 (UTC)

I continue to be grateful for Petergans' addition of the text saying that this list only includes ions characterized with a high degree of certainty, which I understand to mean experimentally verified and with unambiguously characterized stoichiometry. This keeps our list from collecting a huge number of forms whose existence is mere conjecture. That being said, if multiple RS have significant mentions of some species that don't quite meet this standard, and there is a consensus among editors, I support their mention in footnotes. YBG (talk) 05:45, 25 August 2021 (UTC)

A personal comment. Richens did his Ph.D. with Geoff Sykes. Geoff and I were colleagues at Leeds University for a number of years before his move to Newcastle. His research was based entirely on chemical kinetics. This is reflected in Richens' book which discusses kinetics in some detail. Almost all the information on equilibria was taken from Baes & Mesmer' book. I have checked this for every one of the elements. Petergans (talk) 11:35, 25 August 2021 (UTC)

Thanks for fixing Tc and Re (though I think Tc is still a typo).

Is LuOH²⁺ really not well-characterised, when it apparently is for all other lanthanoids? Would be interesting, if unexpected.

One question for a rare element. What do B&M say about polonium? I was under the impression there was a known Po²⁺ cation; is it just not characterised well enough? doi:10.1002/9783527656189.ch15 would be interesting, if I had access. Double sharp (talk) 15:37, 25 August 2021 (UTC)

There is no mention of polonium in B&M! The table entry of PoO₃^2- is extremely dubious on account of the very short half-life of the most common isotope, ²¹⁰Po. Petergans (talk) 20:01, 25 August 2021 (UTC)

See #Polonium below. Double sharp (talk) 04:12, 26 August 2021 (UTC)

​​​​Much as I'm grateful for Peter's expertise, research and associated editing, I feel it's somewhat dangerous to make judgements about the supposed reliability of supposedly reliable sources such as that of Richens. Wikipedia is supposed to be able to edited by anyone including general readers who can support their edits with RS.

I agree with YBG where he wrote, "This keeps our list from collecting a huge number of forms whose existence is mere conjecture" and I mostly agree with him where he wrote, "if multiple RS have significant mentions of some species that don't quite meet this standard, and there is a consensus among editors, I support their mention in footnotes." I say "mostly" since, in the scenario mentioned, I feel the species should be listed in the main table, and consensus shouldn't be able to overrule this, with the exception of WP:DUE or associated wp policy. Who are we to WP:CENSOR what supposedly RS say? That said, the notes column is good place to add a note if there are any concerns about the species in question, provided there are RS to back up such concerns.

These are my initial feelings. Sandbh (talk) 07:12, 26 August 2021 (UTC)

I don't question the reliability of Richens or other secondary sources. The issue of reliability concerns primary sources. Proposals for the identity of trimeric hydrolysis products in solution are based on computer modelling, with virtually no exceptions. The stoichiometry proposed in such situations is based on analogy with what has been identified by X-ray crystallographic determination of structures in the solid state. It is speculated that same structures will be present in solutions, but there is no independent experimental evidence to support such conjectures. The issue arises because solubility is dependent on the magnitude of crystal lattice energy, which is not relevant to matters concerning solutions. For that reason I would exclude trimeric and other polymeric species from the species listed individually in the table. Petergans (talk) 10:49, 3 September 2021 (UTC)

Outstanding: Sandbh (talk) 01:59, 16 September 2021 (UTC)

Top image colors

About the nice top illustration. I have "see"-linked the six colored bottle descriptions to their element in the List table. Like:

 • Turquoise: the nickel cation Ni²⁺ from NiCl₂ (see § Ni)

It occurs that not all written color names between the links are the same (or even worse like omitted). In the Ni example: "turquoise" vs "green". I did not check the visual color in the picture. I expect more correspondence. Can someone take a look? -DePiep (talk) 19:53, 25 August 2021 (UTC)

Thanks, DePiep. This is a nice addition. I've shortened the text a bit, including "see" only on the first one, and now there are no unsightly premature line breaks. YBG (talk) 08:02, 26 August 2021 (UTC)

Improvement. The other point is open: image has caption "the red cobalt", and the table only has "pink; blue-green". -DePiep (talk) 09:20, 26 August 2021 (UTC)

Polonium

Okay, I got Brown and Ekberg's Hydrolysis of Metal Ions:

“ Polonium is known to form a number of oxidation states including Po²⁺. Brown (2001) showed that the stability region (E_h−pH) of polonium(II) was quite narrow, occurring in a region that does not exceed a pH of 6 and is bounded by polonium metal at lower E_h and polonium(IV) at higher E_h. The hydrolytic properties of polonium(II) are expected to be similar to those of lead(II). As a consequence, polonium(II) is not expected to hydrolyse until a pH higher than 6, in a region where it is not expected to be stable. It is not expected, therefore, that polonium(II) hydrolysis species would exist and none have been reported.

Polonium also forms a tetravalent cation, PoO+2. Data are available for both the solubility constant of PoO₂(s) and stability constants for the monomeric hydrolysis species, PoOOH⁺ to PoO(OH)2−4, and the data have been reviewed by Brown (2001). The solubility of PoO₂(s) was studied by Bagnell, D’Eye and Freeman (1955) who demonstrated that the solubility was 0.075 mg l⁻¹ in water and slightly alkaline solutions. From this relationship, the solubility constant was determined to be log K_s12∘ = −6.45±0.20 (Brown, 2001) (the uncertainty has been assigned in the present review). In a later study, Bagnell and Freeman (1957) showed that the solubility of PoO₂(s) in 0.26–1.73 mol l⁻¹ hydroxide had a slope of two, indicating the formation of PoO(OH)2−4 (or, equivalently, PoO2−3) in these alkaline solutions. ...

”

And then a lot of further stuff about past studies from 1964 to 1981.

This book gives a Pourbaix diagram for polonium (admittedly at 10⁻¹² mol L⁻¹ concentration). Present species are:

• Po(VI): PoO₃
• Po(IV): PoO²⁺, PoOOH⁺, H₂PoO₃ (aq), HPoO₃⁻, PoO₃²⁻
• Po(II): Po²⁺
• Po(0): Po (s)
• Po(−II): H₂Po (aq), HPo⁻, Po²⁻

Double sharp (talk) 04:06, 26 August 2021 (UTC)

That's fascinating. But, (there's always a but) at such a low concentration the speciation must be theoretical. Somewhere in WP is a diagram I made showing calculated acid/base titration curves as a function of analyte concentration. Below ca. 10^-6M the curve has no inflection point; in such a situation the pK value cannot be determined experimentally. Petergans (talk) 07:28, 26 August 2021 (UTC)

The aq chemistry of Po is mentioned by G&E, Wiberg, and S&P. The latter write (pp. 241–242):

"Figure 10.8 is the E—pH diagram for Po with all soluble species except H+ at 10⁻⁵ M, a concentration with which a person using special equipment is likely to be working with the element. The equations in the figure legend may be used to arrive at the diagram for any other Po soluble species concentration. The diagram is to be treated with much caution because of several points: ( 1) most of the species identifications have been made on the basis of insufficient experimental data, (2) the Po species assume no complexation with anions except OH⁻ (3) most of the AG" values are estimates based upon what is compatible with most of the experimental information, (4) the influence of the radioactivity on reactions of Po is sometimes not known, and (5) very dilute solutions are known to behave strangely. This strangeness consists of the formation of colloids by adsorption of the ions onto insoluble solution impurities and the failure of the Nernst equation to apply to extremely low concentrations. The species HPo⁻ probably appears in the lower portion of the diagram, but insufficient data are available to provide an estimate."

I feel the species of Po should be shown, with the above caveat. Sandbh (talk) 07:34, 26 August 2021 (UTC)

@Petergans: What do you think should be done with situations like Po, At, and Rn? On the one hand, there has been some work and some likely conjecture, and it seems a shame to ignore it entirely. On the other hand, it is as you said, at such low concentration the speciation is theoretical. I personally think that their likely species should be included, but only in footnotes rather than the main table. Nonetheless I'm ready to be convinced otherwise.

For polonium, anyway, it's just about conceivable that one day we might know better. The half-life of ²¹⁰Po is short (138 days), but that of ²⁰⁹Po is a respectable 125 years. (Pity it's hard to make that isotope in quantity.) For astatine and radon there is probably no hope.

Incidentally Fr must be in the same situation with its 22-minute half-life, even though in this case the likely speciation (Fr⁺) is kind of too obvious to doubt. Brown and Ekberg give for that one a short line: It is thought that the degree of association between the rubidium, cesium or francium ions and the hydroxide ion is such that they would always be fully dissociated. This may be partly because that any association that did occur would be difficult to detect experimentally. They stop at Cf. Double sharp (talk) 08:12, 26 August 2021 (UTC)

My interpretation of policy is that everything that is purely speculative should be excluded from WP articles. Petergans (talk) 09:39, 26 August 2021 (UTC)

Well, my understanding from WP:CRYSTAL was a little bit more nuanced: Predictions, speculation, forecasts and theories stated by reliable, expert sources or recognized entities in a field may be included, though editors should be aware of creating undue bias to any specific point-of-view. Which seems to read, to me, that speculation is alright if it comes from a reliable source. Naturally, though, a lot of care must be taken to avoid it from becoming UNDUE. So I'd interpret it as saying: for a general list like this, including something like At species is not fine, because it creates a double standard between this and iffy polymeric species of various transition metals; for the main article on astatine, it makes sense to include (or else there is hardly anything to say), as long as it is clearly reported as speculative.

But how about this as a footnote for short-lived elements, rather than giving any likely species (Po, At, Rn, Fr, last actinoids Es–Lr): These highly radioactive elements have only been investigated in tracer quantities, and as such unambiguous characterisation of the species they form is impossible. Some theoretical speculations as to what they might be are present in the literature; more information can be found at the main articles of the elements involved. So, making it clear that some work has been done (unlike transactinoids which are left off), but leaving the speculations off for consistency with stable elements? Double sharp (talk) 10:03, 26 August 2021 (UTC)

This would belong in the body of the article as it applies in the same way to a number of elements. Petergans (talk) 14:50, 26 August 2021 (UTC)

Okay, added it above the table. Double sharp (talk) 15:31, 8 September 2021 (UTC)

 Question: Have all the issues in this section been resolved? If not, what discussion or action is remaining? YBG (talk) 06:12, 16 September 2021 (UTC)

The issue is that S&P also write The diagram is to be treated with much caution because of several points: (1) most of the species identifications have been made on the basis of insufficient experimental data, (2) the Po species assume no complexation with anions except OH−, (3) most of the ΔG◦ values are estimates based upon what is compatible with most of the experimental information, (4) the influence of the radioactivity on reactions of Po is sometimes not known, and (5) very dilute solutions are known to behave strangely. The other sources are also not too promising, based as they are on extremely low-concentration measurements (e.g. this article).

However, I did add Po²⁺ since this is at least in Greenwood & Earnshaw, as are the two other already included species Po²⁻ and PoO2−3, though nothing else is (p. 755, 2nd edition). That makes me think it is more sure than the others, especially since a colour was provided by S&P (pink), which suggests a higher concentration (possibly 10⁻⁵ M as they note before giving the diagram). Double sharp (talk) 08:05, 16 September 2021 (UTC)

Astatine (aq)

The 2021 PhD thesis by Liu includes a comprehensive survey of the literature, and a Pourbaix diagram at p. 33. These species merit inclusion, along with the usual caveats. Sandbh (talk) 08:01, 26 August 2021 (UTC)

Are they experimentally verified? Is the stoichiometry unambiguous? YBG (talk) 08:03, 26 August 2021 (UTC)

The astatine species are characterised at tiny concentrations, normally ≤ 10⁻¹⁰ M (Gmelin p. 195). So I think this is the same situation as polonium, though better than radon (and given the even shorter half-life, likely worse). In one recent study the most likely stoichiometry was decided based on running calculations of the possibilities and comparing them against experimental data (doi:10.1002/chem.201504403): the authors even write "This strategy appears to be the only practical way to identify astatine species, since no spectroscopy experiments can be performed at ultra-trace concentrations. The firm identification of the species relies on two hypotheses: 1) the charge is known from experiments (for example, from electromigration or chromatography); and 2) computed quantities significantly differ for the considered species that arise from (1)". (It's about whether an anionic At^III species is really AtO−2 or AtO(OH)−2; they decide it's probably the latter.) This doesn't seem in any way like the sort of unambiguity we can expect for less self-destructive elements. No one could do much better, of course, but again, it seems to be something I'd rather keep in footnotes. Double sharp (talk) 08:18, 26 August 2021 (UTC)

Yea, I agree. In the footnotes.

As an aside, one has to wonder about these self-destructive tendencies. Perhaps caused by traumatic childhood experiences?

YBG (talk) 21:11, 26 August 2021 (UTC)

I've wondered above (in conversation with Petergans) if it might be better not to even give the species, given how it's impossible to identify species for an element like At to the standards we're expecting for stable elements. That would knock out all those trace radioactives, including polonium (at least until someone does work with ²⁰⁹Po; I'm not holding my breath for that). Naturally, it would be a different story for the main articles on Po and At.

I should check which of those radioactives have actually been investigated the way a stable element could be. One would expect technetium and at least the longer-lived actinoids. Double sharp (talk) 15:37, 27 August 2021 (UTC)

Autogenerating the PT based on the list

I am working to replace the list with {{List of aqueous ions}} and the periodic table with {{List of aqueous ions/periodic table}}. Significant features include:

• Both are based on data found in {{List of aqueous ions/data}} so the list and the PT will always be kept in synch.
• There are no known changes to the presentation of the list.
• The list is collapsible -- and, provided it is kept in a separate top-level section, even mobile users will be able to collapse the table
• The periodic table uses a different color scheme from the current table. Rather than reproduce the current color scheme, I chose to use one based on https://colorbrewer2.org/#type=diverging&scheme=Spectral&n=11.
• The color scheme is easily changed by editing {{List of aqueous ions/color}}
• The PT encodes the species slightly differently than the current PT. In the current PT, dual (split) cells are only used when there are three or four species. In this scheme, the cells are split whenever there are both positive and negative ions.
• An alternate list {{List of aqueous ions/list2}} based on User:Petergans/sandbox is also available. This list only includes oxy*ions and hydroxy*ion. IMO this sandbox should be merged into the article without removing the more complete list. (If you wish to discuss this alternate form or merging it into the current article, please do so in a separate section rather than in this one.

Things I would still like to do:

• Turn all references into named references so they can be used in the article by reference if desired.  Not done The refs have been eliminated^{YBG (talk) 22:49, 15 September 2021 (UTC)}
• Improve the color scheme  Not done currently good enough.^{YBG (talk) 22:49, 15 September 2021 (UTC)}
• Add color icons to the "Summary of species" column in the list  Done^{YBG (talk) 03:42, 7 September 2021 (UTC)}
• Expand the template documentation  Partly done^{YBG (talk) 22:49, 15 September 2021 (UTC)}
• Add sandboxes and test cases  Partly done^{YBG (talk) 22:49, 15 September 2021 (UTC)}
• Reduce the color set to four colors with a system similar to the one shown in § Color coding the PT.  Not done for now. ^{YBG (talk) 22:49, 15 September 2021 (UTC)}
• Figure out a way to eliminate the redundancy between the data that supports the two forms of the list. (Currently, completely separate data sets support the two lists.)  Not done Will eliminate alternate form. ^{YBG (talk) 22:49, 15 September 2021 (UTC)}

At some point in the near future I hope to replace the list and periodic table with these templates. Comments, anyone? YBG (talk) 08:40, 5 September 2021 (UTC)

My main concern is with content, not form.

1. Are the proposed species for polynuclear species in solution conjectural or are they based on experimental evidence? The presence of trimeric species in solution is almost certainly conjectural, based on what is known about species identified by crystallography
2. There are gross errors in column 8 due to not distinguishing between oxidation states. The column should be removed.
3. Atomic numbers in column 1 are redundant.
4. Column 3 is redundant now that each oxidation state is shown on a separate line.
5. An issue of fundamental importance is that text-books generally do not distinguish between structures based on conjecture or experimental evidence

These issues should be addressed before making the changes that you propose. A substantial revision is in user:petergans/sandbox (nearly complete); Note that I prefer a plain layout so that other editors can make changes more easily using standard procedures. Petergans (talk) 09:25, 6 September 2021 (UTC)

Thank you, Petergans, for your helpful comments. Although it violates WP:TPO, I changed your bullets to numbers to facility my reply; I trust you do not mind. Here are my comments:

• 1 (polynuclear species) You ask whether these species are conjectural or experimental. I cannot say, but if they are conjectural, then they violate the scope statement in the lede, and should either be removed or else the scope statement should be changed. Do you have a preference between these two options?
• 2 (summary of species) Please list a specific example where column 8 is inaccurate and explain how it is inaccurate, so that I might understand what you mean. I conjecture that you mean that the scandium summary (3: C, xC, xA) is accurate because the same oxidation state (3) forms all three of these ion species (cations, (hydr)oxycations, and (hydr)oxyanions), but that the summary for vanadium (3: C, xC, xA) is not accurate, because no single oxidation state forms all three species: OS2 only forms cations (C only), OS3 forms cations and (hydrox)oxycations(C+xC), OS4 forms (hydr)oxycations (xC only), and OS5 forms (hydr)oxycations and (hydr)oxyanions (xC+xA). If that is what you mean, please say so; if not, please explain with an example so that I may better understand your meaning.
• 3 (Atomic numbers) While it is true that these are redundant, being completely determined by the element name, having the atomic number and symbol enables the reader who is not familiar with the periodic table.
• 4 (OS numbers) If column 3 is removed, the reader cannot tell which rows belong to which oxidation number, nor evey why the ions are shown on different rows. If the ions with different oxidation numbers are to be shown on different lines, then the oxidation numbers IMO must be shown, either in a separate column as currently shown, or as a prefix to each row in the species columns, or with a roman numerals in the chemical formula. ^{See § Alternate ways to display oxidation numbers below. YBG (talk) 08:10, 7 September 2021 (UTC)}
• 5 (by conjecture v. by experiment) You state text-books generally do not distinguish between structures based on conjecture or experimental evidence. By my way of thinking, that means we should generally exclude from consideration sources that do not make this distinction or else we should stop excluding conjectural results. Do you have a preference between these two?

Neither conjecture nor experiment! The process used is one of modelling. In complicated cases that means finding the model that gives the best agreement between experimental data and data calculated for a series of postulated models. An example of the process for aluminium is shown in B&M, p119. There is a general presumption that any species that has been characterized in a crystal structure should be included in the model. "Minor species" are excluded from models on the assumption their concentration in solutions is "very low". Consequently, there is always some uncertainty as to which species have appreciable concentrations in aqueous solution. There is a detailed discussion in B&M, section 18.2. pp. 419-430. Petergans (talk) 13:02, 7 September 2021 (UTC)

Regarding plain layout instead of templates, I agree that it is generally best to use plain layouts. However, in this case, I decided to use the templates so that the list and periodic table could be kept in synch. The current templates do not include the v/e/t buttons that appear in most templates to direct editors to where to edit or discuss the template. Without these it is exceptionally difficult to know how to edit the template, and it would probably be a violation of some WP rule to use such a template.

Thank you for your input! YBG (talk) 23:06, 6 September 2021 (UTC)

I am not convinced that plain layout is preferable. On a wider note, I find it getting tiresome that this article has not evolved into a stable concept to present (and in which the content issues can be developed, as Petergans is promoting). Anyway, a "plain layout" will produce a bulletlist with verbose, non-systematic info. A table, OTOH, presents info in a comprative, relative way. If such a more systematic overview is not preferred, then the title of the article is incorrect. On a more detailed level, it surprises me that there is stil unclarity (between aqua-experienced editors) on whether data like oxidation state and a "summary" is useful or not. (IMO, learning from this article, I'd say OS is obviously helpful & improving structural overview & entrance; need or reason of the element summary is unclear). As for the periodic table overview, I am looking forward to see the {{List of aqueous ions/periodic table}} by YBG in the live article; current version has too many issues (many already mentioned on this talkpage). -DePiep (talk) 14:46, 7 September 2021 (UTC)

• YBG, as you know I am a fan of the PT you created, for this article & for encyclopaedic reasdosd. How can we push forward its publication? (removing current section completely?). — Preceding unsigned comment added by DePiep (talk • contribs) 19:46, 15 September 2021 (UTC)

@DePiep: I've marked the status of my to-do list above; all are good enough for now. But I do have some more things I'd like to do first:

1. Remove unneeded stuff from the template, e.g., the alternate list and the alternate row format  Done^{YBG (talk) 05:49, 16 September 2021 (UTC)}
2. Update the template with the current data from the article.  Done^{YBG (talk) 05:49, 16 September 2021 (UTC)}
3. Generate the multi-line {{hr}} lists automatically from the oxidation-state specific data  Not done I was unable to do this within the note count limit.^{YBG (talk) 07:29, 17 September 2021 (UTC)}

One thing I am not willing to do is to implement the auto-generated periodic table without simultaneously implementing the auto-generated list. The whole point is to make sure that the two presentations of the data stay in synch. YBG (talk) 22:49, 15 September 2021 (UTC)

The template version should match the mainspace version now. I have changed the {{hr}}-divided lists into {{ubl}}-lists. All in all, I believe the unbulleted lists are cleaner than the horizontal ruled lists. As only a few elements have more than four oxidation states, I think it is as legible as the horizontal rule version but much cleaner. This resulted in two positive side effects. First, the lines in the data are shorter and cleaner and so easier to edit. Secondly, the OS sorting no longer requires a complex sort key, though it might be nice to sort first by the number of oxidation states. Any commenets? YBG (talk) 07:29, 17 September 2021 (UTC)

Summary column

@Sandbh, Double sharp, DePiep, Petergans, Droog Andrey, and ComplexRational: For the second time, the summary column has been removed. When it was removed the first time by Petergans, my impression was that most if not all of the other editors who voiced an opinion agreed with me that being able to sort the table so that the elements that have the same combination of species facilitated expIoration and discovery by the reader. If there is a consensus to eliminate this column, so be it. But let us first discuss it.

So, should the sort-by-species-combo column be removed or retained? Please !vote below. YBG (talk) 15:18, 8 September 2021 (UTC)

@YBG: I previously said [1] I’d revert if that column was deleted again. I’ll do so soonish. Sandbh (talk) 11:00, 9 September 2021 (UTC)

@Sandbh and YBG: as you can see, there is a discussion going on right here. As is the correct procedure. Reverting would constitute Editwarring. -DePiep (talk) 11:06, 9 September 2021 (UTC)

@DePiep and YBG: Not so. I can revert in accordance with WP:BRD. Sandbh (talk) 11:29, 9 September 2021 (UTC)

!Votes

• Retain. It is useful and allows the reader to explore and discover. Errors should be dealt with by correction, not by wholesale removal of data. YBG (talk) 15:18, 8 September 2021 (UTC)
• Remove. My reason for removing this column is that it must be, by definition, substantially incomplete. There is considerable uncertainty as to the minor species that might be present in solutions of divalent ion. For trivalent ions the uncertainty is gross, as the speciation is done by modelling and cannot be verified experimentally. To compensate for the removal of the column all those cases for which there is a separate article with relevant details have been linked, in column 6, to that article. P.S. I intend to add an introduction, which outlines all the issues around the determination of speciation. An almost complete draft is in my sandbox.Petergans (talk) 16:10, 8 September 2021 (UTC)

  re incompleteness, please explain. To me,it seems this column is only as incomplete as the data in the other columns. If incompleteness is not a reason for removing the oxyanion column, why would it be a reason to remove the column that summarizes the other columns? Is it because it seems more definite or certain?

  re compensating for its removal, please explain how changing from formulas to linked names compensates for the removal of the summary column. In particular, how does it compensate for the reader's loss of the ability to explore and discover by sorting the elements according to which species they form?

  YBG (talk) 22:59, 8 September 2021 (UTC)

• Remove. This column was added by YBG, with its initial table, within 5d after article creation & first editing flow [2]. Since then, we editors have struggled to explain and clarify its need & usefullness. It also introduced the OR codes like "xC" (ouch); these codes have never helped to describe the List at all and just kept us editors bizzy trying to understand the article ourselves — in a sidetrack. This 'summary' column is not a summary but a meaningless aggregation that does not say anything about the topic (article title).

Quite simple: the column provides some data for the element, but does not enlighten the interested reader about what it purports(!) to say. At all. ("How is this number of types relevant to describe & understand the topic?").

Interesting sidenote: YBG has created a graphic that, to me, actually does illustrate the meaning of anions/cations as related to elements -- and even their periodicity.^*

TL;DR it adds ←meaningless− stats; it does not illustrate the topic nor does it add encyclopaedical information. This is not how tables are read & used. -DePiep (talk) 21:18, 8 Septemb er 2021 (UTC)

^* The image I linked to, a legend-colored periodic table, does this very bright: it shows which elements have aniodic versus cationic ions (reddish versus greenish: a great graphial feature as it turns out); it shows at a glance that this has a PT-periodic pattern too (while keeping incidental elements in sight that are obstinately crossing the line — how Mendeleevian e.g. I/Te). -DePiep (talk) 21:30, 8 September 2021 (UTC)

@DePiep: If I understand you correctly, you would retain the column if it were formatted with the color boxes as the template has. If that is the case, would you support restoring the column when it can be color coded? Or perhaps even supporting its retention in anticipation of it being improved? YBG (talk) 22:36, 8 September 2021 (UTC)

No. The column is a meaningless addup (what does it want to say? We might as well add a column that says 'number of consonants in the element name'). While that PT has an overview of c/a habits of elements, showing a simple periodicity (left/right). -DePiep (talk) 22:43, 8 September 2021 (UTC)

Which ions the element does is already present in the four species-columns; then the indiscriminate listing of the species types present is not informative. The PT shows c or a tilting of each element, revealing a pattern. (Check question: 'What does it purports to say?') -DePiep (talk) 22:49, 8 September 2021 (UTC)

But without this column it is not possible to sort the table so that elements with the same combination of species are together. YBG (talk) 23:04, 8 September 2021 (UTC)

Do you think some readers would appreciate being able to explore and discover by sorting the table so that elements having the same combination of ion species are together? YBG (talk) 23:09, 8 September 2021 (UTC)

How is that describing the phenomenon of aqueous ions? Why are these cases to be grouped (by sorting)? My personal (i.e., uninitiated) quest would be for elements that produce both positive and negative ions, 'how could that be?'; this is covered in the PT. Maybe this is less relevant too -- then I need to learn that (no PT at all?). Compare, also intertesting is that there are elements that show multiple oxidation states. But add a sort (grouping) option for this? The article now just states that there are these types of ions, ok. Is the mechanism (chemistry) behind thi s to be dscribed? Why would a combining element be of interest? -DePiep (talk) 05:46, 9 September 2021 (UTC)

Good point regarding multiple oxidation states. It is in fact interesting that some elements have but a single oxidation state while others have two, three or even more. The current sort on that column sorts by the least positive state first, then by the 2nd least positive state, and so on. I think it would be an improvement to sort first by the number of oxidation states and then by the particular grouping. YBG (talk) 15:01, 14 September 2021 (UTC)

• Retain. I’ve found that column to be a useful tool. For example, to quickly determine how many elements are confined to either cations or anions, these elements being the most metallic or nonmetallic.

If abbreviations such as xC are too hard to understand then this can be explained better rather than throwing out the whole column.

Of course the information is incomplete. So what? Many aspects of science are like that yet we do the best we can with what we have, and fill in the gaps as we learn more.

To deny folks the option to further sort the data beggars the imagination.

It is our job to present reliable information, incomplete our not.

It is not our job to make judgements about how other folks may or may not be allowed to sort that information e.g. along the lines of my opening example. Sandbh (talk) 11:24, 9 September 2021 (UTC)

Status of RFC

@Sandbh, Double sharp, DePiep, Petergans, Droog Andrey, and ComplexRational: This result of this RFC appears to be "No consensus", although at least one sub-thread still has unanswered questions in it. When the column was boldly removed, I immediately responded by attempted to revert and then initiated this discussion. Unfortunately, I reverted the wrong edits and it was several days before I realized that I had failed to follow the "R" of "BRD". By this point, it would have been very difficult to restore the column. I am content to leave the column out for the present to ease the burden of those who are editing a table that still is in a bit of flux. I may choose to reinstate it at a later date. YBG (talk) 15:01, 14 September 2021 (UTC)

I might slightly disagree with your "no consensus" conclusion, but I understand all this is moot. -DePiep (talk) 19:41, 15 September 2021 (UTC)

@DePiep: It sounds like your might be saying that a consensus was reached in the above discussion, but perhaps I misunderstood you. YBG (talk) 05:53, 16 September 2021 (UTC)

Yes, I think I can see a line towards a consensus. But it's moot innit? -DePiep (talk) 11:04, 16 September 2021 (UTC)

@DePiep: Not sure what you mean by "a line towards a consensus" when only four parties expressed an opinion, they were evenly divided, and there appears to be no objective reason to prefer the reasoning of one side over the other. Or rather, perhaps I should say that both sides see good reasons for agreeing with thier side and dismissing the reasoning of the other side, hence the stalemate with no consensus.

It is definitely not moot. If there were a consensus on the current form, those who think a different form would be preferable would be reticent to propose a change. With no consensus, the threshold for change is lower.

As for BRD, as you point out, the column was present when the list was first created, and remained there for most of the article's life. Petergans removed it once, and it was promptly restored. He removed it a second time, and I attempted to restore it, but wasn't paying close enough attention to notice that I was reverting the wrong edit. So I think it would be fair to say that the presence of the column has a higher claim on "status quo" than does the absence. By all rights, the column should have remained until there was a consensus to remove it. But that ship has sailed. YBG (talk) 03:57, 17 September 2021 (UTC)

I noted that I might disagree with you on the conclusion of this mini-RFC. However, since you imply that there is no action following, it is pointless to discuss your closure. -DePiep (talk) 12:12, 17 September 2021 (UTC)

Radioactive elements

Just a holding thread for the radioactives. I added a disclaimer about the too-ephemeral ones above the table.

• Francium – Fr⁺ is obvious, especially because of coprecipitation with Cs⁺, but what level of proof are we demanding for these? Certainly the concentrations cannot have been impressive. Not in Brown & Ekberg, but that is about hydrolysis of metal ions, which would not be significant for a heavy alkali metal.
• Protactinium – are we sure about Pa³⁺? Not in Brown & Ekberg either, who only consider +4 and +5 oxidation states. Pa(III) is in brackets in Greenwood & Earnshaw (2nd ed. p. 1265).
• Similarly Brown & Ekberg do not include heavier actinoids past californium, but this may be the same sort of situation as francium, where at least the aqua-cation species and oxidation state is obvious.
• A lot of hydrolysis data for promethium is pretty suspect according to Brown & Ekberg, yet periodicity (in the sense of homogeneity of lanthanoids) suggests that the species themselves should be right.
• Technetium – There's some hydrolysis data in Brown & Ekberg for TcO²⁺ (hydrolysed to −1 charge).
• Polonium – likewise Po²⁺ (just the cation) and PoO²⁺ (hydrolysed to −2 charge). (Note, current article does give technetium and polonium species, but different ones).

No data is given for astatine or radon.

Will probably need to follow up and look at the concentrations used to determine these. Double sharp (talk) 13:35, 14 September 2021 (UTC)

The half-life of Technetium-99m is long enough for reliable data regarding hydrolysis to be obtained. Petergans (talk) 08:29, 15 September 2021 (UTC)

Never mind about technetium. Schweitzer & Pesterfield only give TcO₂ for Tc(IV). Double sharp (talk) 08:13, 16 September 2021 (UTC)

Other oddities in current table

The last column for mercury seems at least wrongly placed (not an anion). Double sharp (talk) 13:38, 14 September 2021 (UTC)

Fixed. Petergans (talk) 07:57, 15 September 2021 (UTC)

 Resolved

Is there really not Lu(OH)²⁺ as there is for all other rare earths (including scandium and yttrium)? Double sharp (talk) 08:18, 16 September 2021 (UTC)

Most probably the ion is formed just before a precipitate of Lu(OH)₃ comes out of solution, but I know of no pK values for it in the literature, so its formation is conjectural. I also have doubts about all the entries for trans-plutonium elements, for which Baes & Mesmer state (p.191) "the best information is that obtained by analogy drawn with the lanthanides". Petergans (talk) 10:39, 16 September 2021 (UTC)

A note about hot edits

A note to Petergans. I don't know we met outside of this article page. I opened this section to express my concerns wrt disputed edits, involving you. I "had to" revert an edit by you recently, and that is not the most pleasant way to interact.

I want to note that your edits in this article, especially the blanket ones, are not that obvious as you might think yourself. Other editors, qualified themselves too surely, have different opinions as to how to improve the topic into a good encyclopedic article. Maybe a GA or FA might be reached.

It is my impression that your edits are easily controversial. Please do check this wiki-concept. When controversial, much more communication is needed. That is where this talkpage is for. The preferred wiki-process is: to gain consensus.

Note that I do address you but do not not blame you, singled out. My point I want to convey is, that too little talk & development does not help the article, our encyclopedia. -DePiep (talk) 19:25, 15 September 2021 (UTC)

Regarding the column "oxidation states". The concept of oxidation and reduction is taught at the most elementary level and can be regarded as common knowledge. It follows that entries in this column are essentially redundant, except where there are data for more than one OS. In that case, the OS value and data for compounds in each OS are shown in the separate rows of the table.

The number of charges on a cation is exactly the same as the oxidation number. Showing the OS in these cases just adds clutter to the table. For oxyanions like CO₃^2- the OS is irrelevant. For ions like nitrite and nitrate, showing the OS on each line of the table is helpful.

What is controversial in these remarks? Petergans (talk) 10:13, 16 September 2021 (UTC)

I am not convinced that it's common knowledge for heavy transition metals like Nb, particularly since in that case a formula can hardly be provided. Double sharp (talk) 16:18, 17 September 2021 (UTC)

• Petergans. I just reverted your edit [3], see the es. This level of non-communication is not helping the arrticle, an so is disruptive to our encyclopaedia. -DePiep (talk) 21:52, 17 September 2021 (UTC)

I feel that a "common knowledge" argument won't cut it at WP:FAC. Articles/lists are expected to be comprehensive. The general reader, which is the wp target audience, may not know what is common knowledge. Sandbh (talk) 02:15, 18 September 2021 (UTC)

I don't understand why we are at cross-purposes. The oxidation state of an element is only used in this table to classify the hydrolysis products, with each OS on a separate line of the table. Otherwise it is completely redundant. The "general reader" argument is spurious: the table will be incomprehensible to someone who does not have enough knowledge of chemistry to understand what a chemical formula means. Petergans (talk) 07:12, 18 September 2021 (UTC)

The reason why speciation is so difficult to determine is that glass electrode#limitations are prone to secondary effects that cannot be quantified. This has 2 main consequences. i)The electrode must always be calibrated before making pH measurements with it and ii) The precision of pH measurements is generally no better than ± 0.01. The limited precision places severe limits on what can be achieved in determining which species are present in metal hydrolysis systems. In those cases where dimeric species are formed it may be possible if multiple data sets are used. It is impossible to quantify all the intermediates that must be present to form polymeric hydrolysis products. I considered moving all higher polymeric species from specific to generic mention in the table, but have hesitated to do it. Should they be identified in some way so as to indicate that their presence is likely, without there being any direct evidence for it? Petergans (talk) 10:42, 18 September 2021 (UTC)

Petergans, what you did is WP:Edit warring. It is unacceptable, and is not the way to improve the article. You are expected to 1. revert your edit, and 2. seek WP:CONSENSUS. -DePiep (talk) 12:16, 18 September 2021 (UTC)

Even the general reader is likely to have heard of H₂O and carbon dioxide. It's not too hard from there to get the gist of other formulae. Sandbh (talk) 13:06, 18 September 2021 (UTC)

This seems right to me. I distinctly remember hearing about H₂O and CO₂ (as formulae) before I first learned any chemistry. Double sharp (talk) 14:10, 18 September 2021 (UTC)

(Off-topic this is) Yes, everybody recognises "H₂O" and "CO2". So "Be(OH)2−4" is obvious too? -DePiep (talk) 20:32, 18 September 2021 (UTC)

It's not obvious, indeed. But if the reader can be counted on to know two formulae, then we know it's not a totally new concept, and it can be introduced just by linking to chemical formula. Double sharp (talk) 03:53, 19 September 2021 (UTC)

Color of Cr³⁺

Solutions containing Cr(III). From left to right: Cr₂(SO₄)₃, Cr(NO₃)₃, CrCl₃.

The color of Cr³⁺ is not green without Cl⁻. --Leiem (talk) 08:03, 18 September 2021 (UTC)

Excellent illustration! Note how the apparent colour of these solutions is dependent on the concentration of the chromophore. Petergans (talk) 11:00, 18 September 2021 (UTC)

Yes, S&P give varying colours for the colour of Cr(III) depending on the anion. They say Cr(HOH)₆⁺³ is violet but show Cr+3(aq) as being green on their Pourbaix diagram. They go on to say that Cr forms two oxides of interest to its aq chemistry, and that adding OH⁻ to a solution of Cr³⁺ obtains green hydrated Cr₂O₃. Sandbh (talk) 06:53, 19 September 2021 (UTC)

Repeated reversion

User:DePiep has once again reverted my edit. Repeatedly reverting edits without discussion is not acceptable behavior. Petergans (talk) 20:23, 23 September 2021 (UTC)

Per wikipedia guidelines: you either seek consensus or you might be blocked for editing. It has been explained to you before. -DePiep (talk) 20:44, 23 September 2021 (UTC)

I reverted [4]. -DePiep (talk) 20:59, 23 September 2021 (UTC)

Mini-RfC: What is the best way to show oxidation states within each element?

OS-within-element options

​​​​​​​​ Here are several options for how the oxidation states can be listed within each element; each one can be collapsed so you can easily compare any two of them. Please let me know if there are additional style options you would like included or if there are additional element examples you would find helpful; I would be glad to add them. YBG (talk) 04:57, 2 October 2021 (UTC)

Option 1. One row for each OS, repeated labels
Element	Oxidation state	Cations & Anions	Oxycations & hydroxycations	Oxyanions & hydroxyanions
12 Magnesium	+2	Mg2+	Mg(OH)+, Mg4(OH)4+4
24 Chromium	+2	Cr2+ (blue-green)
24 Chromium	+3	Cr3+ (green)	Cr(OH)2+, Cr(OH)+2, Cr2(OH)4+2, Cr3(OH)5+4
24 Chromium	+6			chromate and dichromate
84 Polonium	−2	polonide
84 Polonium	+2	Po2+
84 Polonium	+4		PoO2−3

Option 2. One row for each OS, blanks below 1st
Element	Oxidation state	Cations & Anions	Oxycations & hydroxycations	Oxyanions & hydroxyanions
12 Magnesium	+2	Mg2+	Mg(OH)+, Mg4(OH)4+4
24 Chromium	+2	Cr2+ (blue-green)
	+3	Cr3+ (green)	Cr(OH)2+, Cr(OH)+2, Cr2(OH)4+2, Cr3(OH)5+4
	+6			chromate and dichromate
84 Polonium	−2	polonide
	+2	Po2+
	+4		PoO2−3

Option 3. One row for each OS, rowspanned labels
Element	Oxidation state	Cations & Anions	Oxycations & hydroxycations	Oxyanions & hydroxyanions
12 Magnesium	+2	Mg2+	Mg(OH)+, Mg4(OH)4+4
24 Chromium	+2	Cr2+ (blue-green)
	+3	Cr3+ (green)	Cr(OH)2+, Cr(OH)+2, Cr2(OH)4+2, Cr3(OH)5+4
	+6			chromate and dichromate
84 Polonium	−2	polonide
	+2	Po2+
	+4		PoO2−3

Option 4. One row for each element, line-divided list
Element	Oxidation state	Cations & Anions	Oxycations & hydroxycations	Oxyanions & hydroxyanions
12 Magnesium	+2	Mg2+	Mg(OH)+, Mg4(OH)4+4
24 Chromium	+2 +3 +6	Cr2+ (blue-green) Cr3+ (green)	Cr(OH)2+, Cr(OH)+2, Cr2(OH)4+2, Cr3(OH)5+4	chromate and dichromate
84 Polonium	−2 +2 +4	polonide Po2+	PoO2−3

Option 5. One row for each element, unbulleted list
Element	Oxidation state	Cations & Anions	Oxycations & hydroxycations	Oxyanions & hydroxyanions
12 Magnesium	+2	Mg2+	Mg(OH)+, Mg4(OH)4+4
24 Chromium	+2 +3 +6	Cr2+ (blue-green) Cr3+ (green)	Cr(OH)2+, Cr(OH)+2, Cr2(OH)4+2, Cr3(OH)5+4	chromate and dichromate
84 Polonium	−2 +2 +4	polonide Po2+	PoO2−3

Option 6. One row for each element, bulleted list
Element	Oxidation state	Cations & Anions	Oxycations & hydroxycations	Oxyanions & hydroxyanions
12 Magnesium	+2	Mg2+	Mg(OH)+, Mg4(OH)4+4
24 Chromium	+2 +3 +6	Cr2+ (blue-green) Cr3+ (green)	Cr(OH)2+, Cr(OH)+2, Cr2(OH)4+2, Cr3(OH)5+4	chromate and dichromate
84 Polonium	−2 +2 +4	polonide Po2+	PoO2−3

OS-within-element !votes

Here are the options illustrated above.

• 1. One row for each OS, repeated labels
• 2. One row for each OS, blanks below 1st
• 3. One row for each OS, rowspanned labels
• 4. One row for each element, line-divided list
• 5. One row for each element, unbulleted list
• 6. One row for each element, bulleted list

Please indicate your preference(s) among these options, with brief reasoning. YBG (talk) 04:57, 2 October 2021 (UTC)

• 4>5>>6>3>2>1 Changed from 5>4>6>>3>2>1 5 is the cleanest and least cluttered by unneeded lines. YBG (talk) 04:57, 2 October 2021 (UTC).

  Changed to 4>5>>6>3>2>1. Up-voting my evaluation of line separations; in deference to fellow editors' opinions and because I have recently discovered that the line separation can be improved from the above by using <hr style="margin-left:5%;margin-right:5%;"/> YBG (talk) 20:03, 5 October 2021 (UTC)

• 3~4>2>5>1>6. I think the horizontal lines help to guide the eye, which may be useful for elements with many common oxidation states; I don't particularly mind if it is done as (3) or (4). Even (2) is kind of okay for me; (1), however, gets tiresomely repetitive IMHO. The empty bullets in (6) look kind of ugly to me. Double sharp (talk) 05:57, 2 October 2021 (UTC)

  Oops, the tables were meant to be sortable; they are now. Is your answer the same after seeing how sorting works? YBG (talk) 06:48, 2 October 2021 (UTC)

  Good point. I see the rowspan in (3) makes sorting horrible (I keep forgetting that it does). So I'd prefer 4>5>6>>1>3>2 if the list is supposed to be sortable. That said, I do not quite get why it needs to be sortable: nothing seems to be gained from it. Double sharp (talk) 08:00, 2 October 2021 (UTC)

• 3~5>4>6>2>1. 3 and 5 are the simplest and cleanest. --Leiem (talk) 11:49, 2 October 2021 (UTC)
• 3 or 1. They look the same to me. Sandbh (talk) 04:00, 5 October 2021 (UTC)
• Not #6. And let's stop giving @Petergans: oxygen & our_time wasted for their noncommunicating editwarring. -DePiep (talk) 18:48, 6 October 2021 (UTC)

OS-within-element discussion

Please include any extended discussion here. YBG (talk) 04:57, 2 October 2021 (UTC)

I'd like to be able to sort the table using the oxidation state column. Option 2 seems to be the only one to do this consistently? Sandbh (talk) 04:16, 3 October 2021 (UTC)

So you'd like to be able to separate the oxidation numbers of each element up, so that all +2 ions are together, and elements are split apart. Do I understand you correctly? YBG (talk) 00:38, 5 October 2021 (UTC)

If so, then #1 and #3 will also do this. #4-6 only sort elements, not the OS of each element. They can be configured as the current article is, by (1) the number of oxidation states, then (2) the lowest oxidation state, then (3) the 2nd/3rd/etc lowest oxidation state. Alternately, the sort could be configured to ignore the number of oxidation states and simply sort by the 1st, then 2nd, then 3rd/4th/etc oxidation state. If we opt for any of 4/5/6, we should reach a consensus on which of these orders should be used.

Yes, I support either #1 or #3. They look the same to me. Sandbh (talk) 03:58, 5 October 2021 (UTC)

Look closer. They are different, but only until one of the sort buttons has been pressed, after which they are indeed identical. YBG (talk) 04:00, 6 October 2021 (UTC) Moved to discussion section where this belongs. Also removed redundancy. YBG (talk) 04:05, 6 October 2021 (UTC)

Improved presentation

Unfortunately I have simultaneously produced an alternative way to present the information. Because it affects the whole table it had to replace the current version. Other proposals are given above.

The revisions were made with the aim of making it easy for inexperienced editors to make further changes. The table has been split into 3 separate tables. This has meant that the coding of each table could be fairly simple. Further changes of content are indeed needed, as can be seen in the many gaps in the first two tables.

The content of the first table is very technical and so is unsuitable for editing by beginners. The existence, in solution, of trimeric species and higher polymers is questionable. The species listed are those that have been identified by crystallographic procedures, but it is likely that other (unidentified) species will also be present in the solutions. Column 3 (cations) in the first table is essentially redundant, but does help to make the table more comprehensible.

The second table (colours) will be accessible to all editors. Some of the colour descriptions are questionable. Indeed, the apparent colour of a solution will depend, to some extent, on the concentration of the chromophore.

The third table just contains links to articles on anionic species other than hydroxy- and oxy-anions.

Constructive comments will be appreciated. Petergans (talk) 08:01, 2 October 2021 (UTC)

• I like the separation, and also keeping together just the cations with their hydrolysis products. (Treating of course things like nitrates as "hydrolysis products" of a hypothetical very acidic "N⁵⁺".)

I don't particularly mind the removal of most oxidation states now (as often they are either redundant, e.g. for Li⁺, or vary like for Ir polymeric anionic species, or can be gotten from the links). But it seems others do not agree, and there are a few cases with no link (e.g. niobium(V)) that need some knowledge of those elements' chemistry to deduce. Double sharp (talk) 08:14, 2 October 2021 (UTC)

• @Petergans: As has been explained to you before, there is no consensus for the changes you made to the article. Please revert. Read and understand WP:Edit warring. -DePiep (talk) 10:48, 2 October 2021 (UTC)
• @Petergans: I have lost count of the number of times you have made major changes without consensus. There are many different proposals for how this should be presented, and I am willing to abide by a consensus even if it is not my preference. This is the reason why I began the Mini-RfP above, to which I invite you to participate. I welcome your attempts to improve the article, but you should expect that any major changes are subject to reversion, and once that is done, the status quo should be retained until a discussion results in a consensus. YBG (talk) 15:04, 2 October 2021 (UTC)
• Comment Petergans is allowed to make major changes without the need to obtain consensus, per WP:BRD. OTOH once a consensus is established (which does not require unanimity) a subsequent change to that consensus is incivil and can be reverted without the need for further discussion as to the reason for the revert. Continual ignorance of consensus warrants referral to an admin and, after that, to ANI. Sandbh (talk) 23:53, 17 October 2021 (UTC)

Thats's only half of it. Once declared controversial (or oppposed), the edit may be reverted and editors are expected to build consensus for the change. BRD does not declare "rights", but an attitide. -DePiep (talk) 05:31, 18 October 2021 (UTC)

Mini-RfC: Row headers

What should be the format for element row headers?

• What information should be included? Z (atomic number), Name, Symbol?
• Should these components be in separate columns or all in one column?

Specify your choice, using hydrogen as the example and "|" to for column dividers, e.g., | 1 | Hydrogen | for the current form with atomic number and element name in separate columns. YBG (talk) 10:33, 4 October 2021 (UTC)

• | 1 Hydrogen (H) | single column with all info, preferably left-justified. YBG (talk) 10:33, 4 October 2021 (UTC)
• Support. Sandbh (talk) 22:56, 4 October 2021 (UTC)
• | 1 | Hydrogen (H) | Separate Z and names to give flexibility in sorting (this matters IMO because the table is sortable), though no need to separate the symbol as well. ComplexRational (talk) 19:15, 5 October 2021 (UTC)
• | 1 (|?) Hydrogen (H) |: show all three id's; number of columns 1 but could be 2/3.

Also re-add |- id="H" anchors [5]

In multiple columns is disputable to me, (a) why sort on name or symbol, not F3-search (modern mobile usage?)? (b) effects in mobile screen esp wrt width? -DePiep (talk) 06:41, 6 October 2021 (UTC)

rephrased: In 1 column (Z first). Why use 2 or 3 columns? For the content, the only reasinable sorting would be by Z; names & symbols do not make a logical (chemical) order. But maybe sorting by name/symbol is useful for searching/browsing? How then, what is the approach when doing this search? Do people really sort-then-scroll to look for say 'gold'? If so, then use 2/3 columns. I am not yet convinced. -DePiep (talk) 10:04, 7 October 2021 (UTC)

Mini-RfC: Oxidation number format

It has been previously agreed to display the oxidation number everywhere, even when an element has only one state. The question now is, How should oxidation numbers be displayed?, specifically should the plus sign be included and what should be used for the negative sign?

!votes re OS number format

• +n, −n because "+" makes makes the sign explicit; and "−" (&minus;) is graphically more similar to the plus sign than "-" (hyphen) or "–" (&ndash;). YBG (talk) 20:54, 5 October 2021 (UTC)
• Oxidation state is essentially redundant. It helps to distinguish rows in the table belonging to an element that has more than one oxidation state. There is no element that has more than one negative oxidation state. Petergans (talk) 15:56, 6 October 2021 (UTC)

Discussion re OS number format

@Petergans: I have added subsection-headers to clearly distinguish between !votes and discussion, and invite you to move your comment into this discussion section if you agree with me that it is a discussion rather than a !vote.

By the way, we all understood that OS is "essentially redundant" when we reached a consensus to include it in every row (see archive 1 §§ Conclusions re "Table changes"​ and Oxidation numbers, which are summarized at the § top of this talk page).

The question now is, given that OS is to be shown everywhere, how should they be displayed? In particular, should the positive sign be used, and what character should be used for the negative sign? Of course, this would be a moot point if you decide to start a new top-level thread to change the previous consensus, and if that discussion results in a new consensus to omit the OS. YBG (talk) 18:37, 6 October 2021 (UTC)

• No, not another "mini-RfC", about another obviously non-consensus edit (thanks for the careful effort btw, YBG). Petergans is abusing the system, and GF editors' energy. Jee, are we supposed to retrieve arguments from the archive [6]? -DePiep (talk) 19:00, 6 October 2021 (UTC)

I just tried sorting the oxidation state column to see which elements have negative oxidation states but it does not work. The results are scrambled. Sandbh (talk) 22:18, 12 October 2021 (UTC)

@Sandbh: As currently laid out, each table row is an element with all of its oxidation states. Sorting by the OS column sorts the elements by (1) their numerically smallest OS, then in case of ties, the next-smallest OS, and so on. So when I sort this is what I see

1. Elements w/ no ions listed: He, Ne, Ar, Kr, At, Rn, Rf+
2. Elements whose smallest OS is -3: (-3,+3,+5): As
3. Elements whose smallest OS is -2: (-2): O; (-2,+2,+4): Po; (-2,+4,+6): S, Se, Te
4. Elements whose smallest OS is -1: (-1): Fl; (-1,+1,+3,+5,+7): Cl; (-1,+5,+7): Br, I
5. Elements whose smallest OS is +1: * * *

Please let me know if you see any order other than He, Ne, Ar, Kr, At, Rn, Rf+, As, O, Po, S, Se, Te, Fl, Cl, Br, I, ...

And since you're in this section, please indicate your preference for how to format positive and negative OS. YBG (talk) 00:53, 13 October 2021 (UTC)

History of article name changes

• 2021-07-16: Periodic table (aqueous chemistry) (Sandbh: Created page with this name)
• 2021-07-23: List of ions in aqueous chemistry (YBG: To better reflect article content)
• 2021-07-26: List of ions in pure water (aqueous chemistry) (Sandbh: The scope of article was limited to ions in pure aqueous solution rather than the entirety of aqueous chemistry)
• 2021-07-27: List of stable ions in pure water (aqueous chemistry) (Sandbh: Refine scope of the article---it was never intended to cover anything bar stable ions)
• 2021-07-29: List of aqua-ions and their hydroxo- and oxo- derivatives in aqueous solution (Sandbh: Better captures the scope of the article)
• 2021-08-08: List of aqueous ions by element (YBG: Per suggesion by User:Mdewman6 at WP:CHEM)

I wondered about this and thought others might also. YBG (talk) 04:41, 6 October 2021 (UTC)

I think current name is best. (Second option would be: look for the YBG ones). -DePiep (talk) 19:01, 6 October 2021 (UTC)

I may have implemented the current title, but User:Mdewman6 suggested it. YBG (talk) 01:29, 7 October 2021 (UTC)

Related discussions

Here are a couple of discussions related to this article that page watchers may not be aware of:

• User talk:Materialscientist § Repeated and persistent reversion special:permalink/1048705161 § Repeated and persistent reversion
• WT:CHEM § List of aqua-ions and their hydroxo- and oxo- derivatives in aqueous solution

YBG (talk) 01:27, 7 October 2021 (UTC)

Added link to discussion just prior to delete-archival. YBG (talk) 06:28, 12 October 2021 (UTC)

Mini-RFC: Sorting

Should the main list be a sortable table or not? ​​​​​​​​​​​​​​ After considering this question, please also consider the other mini-RfC's listed at § top. YBG (talk) 08:00, 11 October 2021 (UTC)

!Votes re sorting

Please indicate your preference here.

• Uncertain (see comments below) YBG (talk) 08:00, 11 October 2021 (UTC)
• Remove No purpose is served by making all columns sortable. The only column where there is any point to it is the oxidation state column. However, the sortable tag applies to all columns. Therefore, on balance, I vote to remove the sort option altogether. Petergans (talk) 10:11, 11 October 2021 (UTC)
• Sortable where the slightest bit relevant. (This would exclude columns with only references or so). It is the most obvious way to list those elements with a column property. -DePiep (talk) 14:19, 11 October 2021 (UTC)
• Support sorting for all columns. where technically feasible. Let the reader decide what value or purposes they get out of sorting. I recall several occasions, in other pages or sites, when I would like to sort a column in a table, but for some "beyond my ken" thinking, that option is not made available. I have even seen cases where some columns can be sorted but others can't! Not allowing a sort of all columns reminds me of other attempts here, and in other wp articles, to "hide" information. Why? How reader unfriendly! Sandbh (talk) 05:43, 12 October 2021 (UTC)moved here by YBG (talk) 06:10, 12 October 2021 (UTC)

Discussion re sorting

Comments by YBG

I have become ambivalent about this

1. Element - Sorting by this column is not useful in itself, but just to restore the order after sorting by another column.
2. Oxidation state - With the one-table-row-per-element form (with OS stacked within cells) I find it interesting to sort the elements by which element have the most oxidation states, but I'm unsure of the value of this for the general reader. With the one-table-row-per-OS form (with multiple rows per element) this allows sorting all +1 (or -1 or +2 or whatever) oxidation states together. We already have {{List of oxidation states of the elements}} (transcluded into oxidation state) which does a much better job of showing this in the general case; why would one need to do this just for the OS present in aqueous ions?
3. Species columns (Cations+Anions / (hydr)oxycations / (hydr)oxyanions) - Again I find it interesting to sort the table so that the elements with and without a particular variety of ion, but I am unsure of the value of this for the general reader. And while this sort divides the table into those that have a particular type of ion and those that do not, any sorting within those two groups is for all practical purposes pseudo-random.
4. Combination of species (the now-deleted summary column) - Sorting by this column is the most interesting to me, but as the column is no longer present in the table, it can hardly be a reason to make the table sortable. And while I am certain of the usefulness of sorting by this column for me, I am unsure of the value to the general reader.

Nevertheless, there is a case to be made that sorting is a useful feature that allows the reader to interact with the table as a way of exploring the data. I am much less certain today that this is a strong reason for sorting. But while I have become ambivalent about sorting, I remain firmly committed to consensus. So I welcome the opinions of others on this subject. YBG (talk) 08:00, 11 October 2021 (UTC)

Comments by Petergans

moved here by YBG (talk) 16:43, 11 October 2021 (UTC)

• Remove No purpose is served by making all columns sortable. The only column where there is any point to it is the oxidation state column. However, the sortable tag applies to all columns. Therefore, on balance, I vote to remove the sort option altogether.

An alternative was included previously, but was reverted. This is to sort the elemental anionic species into a separate table, as below. The logic of this is that the listed anionic species in that table are irreversible hydrolysis products, whereas the main table would only be concerned with reversible hydrolysis.

Anions of the elements in aqueous solution

Element	Anions
Oxygen	hydroxide
Fluorine	fluoride
Sulfur	Hydrogen sulfide
Chlorine	chloride
Arsenic	arsenide
Selenium	hydrogen selenide
Bromine	bromide
Tellurium	Hydrogen telluride
Iodine	iodide
Polonium	polonide

References

Petergans (talk) 10:11, 11 October 2021 (UTC)

Comments by DePiep

Unlike what Petergans says in their !vote, sorting can be excluded per column. (Also, btw, certain rows can be fixed at tehe bottom).

Sorting by oxidation state is obviously usefulk. Also, soring in e.g. anions/cations column (preferably by OS) simply lists elements that have cations. How easy can it be. Columns with obviously no addition (like a refecences-column) could be excluded. This all hold true when coilumns are into an other fashion. -DePiep (talk) 14:24, 11 October 2021 (UTC)

Adding: when sorting more smartly than siply by visible cellcontent, the table separation Petergans proposes above can be obtained in the main table (iow, sort those links together and voila). Apart fromn this, the argument to separate these ions does nto hold. -DePiep (talk) 14:29, 11 October 2021 (UTC)

Don't interrupt my post. -DePiep (talk) 16:43, 11 October 2021 (UTC)

Please explain. The current use does apply to the whole table - {|class="wikitable sortable" — Preceding unsigned comment added by Petergans (talk • contribs) 15:05:05, 11 October 2021 (UTC)

@Petergans: Making specific columns unsortable is explained in Help:Sorting § Restrictions and exclusions YBG (talk) 16:47, 11 October 2021 (UTC)

My recent reverts

I have reverted the last two edits by Petergans

• Special:Diff/1050260291 reverted Special:Diff/1050028044. Petergans duplicated a reference; I restored the previous named reference which ensures that two different footnote markers point to the same reference.
• Special:Diff/1050138812 reverted Special:Diff/1049902341. Petergans removed anions from the main table; I restored them, according to the consensus documented at Talk:List of aqueous ions by element/Archive 1 § Separating anions. This consensus was supported by every one who voiced an opinion. These seven supporters represent fully half of the 14 editors who have edited the either the article or the talk page or both, all of whom were invited by ping to participate in the discussion.

Anyone who disagrees with my reverts is welcome to discuss them here. YBG (talk) 19:28, 16 October 2021 (UTC)

• Support -DePiep (talk) 22:29, 16 October 2021 (UTC)
• Support -Sandbh (talk) 23:47, 17 October 2021 (UTC)