In chemistry, a nonmetal is a chemical element that usually gains one or more electrons when reacting with a metal and forms an acid when combined with oxygen and hydrogen. At room temperature about half are gases, one (bromine) is a liquid, and the rest are solids. Most solid nonmetals are shiny, whereas bromine is colored, and the remaining (gaseous) nonmetals are colored or colorless. The solids are either hard and brittle or soft and crumbly and, in contrast to most metals, tend to be poor conductors of heat and electricity with no structural uses (as is the case for nonmetals generally).
There is no universal agreement on which elements are nonmetals; the numbers generally range from fourteen to twenty-three, depending on the criterion or criteria of interest.
Different kinds of nonmetallic elements include, for example, (i) noble gases; (ii) halogens; (iii) elements such as silicon, which are sometimes instead called metalloids; and (iv) several remaining nonmetals, such as hydrogen and selenium. The latter have no widely recognised collective name and are hereafter informally referred to as "unclassified nonmetals". Metalloids have a predominately (weak) nonmetallic chemistry. The unclassified nonmetals are moderately nonmetallic, on a net basis. Halogens, such as bromine, are characterized by stronger nonmetallic properties and a tendency to form predominantly ionic compounds with metals. Noble gases such as xenon are distinguished by their reluctance to form compounds.
The distinction between different kinds of nonmetals is not absolute. Boundary overlaps, including with the metalloids, occur as outlying elements among each of the kinds of nonmetals show or begin to show less-distinct, hybrid-like, or atypical properties.
Although five times more elements are metals than nonmetals, two of the nonmetals—hydrogen and helium—make up about 99% of the observable universe by mass. Another nonmetal, oxygen, makes up almost half of the Earth's crust, oceans, and atmosphere.
Nonmetals largely exhibit a breadth of roles in sustaining life. Living organisms are composed almost entirely of the nonmetals hydrogen, oxygen, carbon, and nitrogen. A near-universal use for nonmetals is in medicine and pharmaceuticals.
Definition and applicable elementsEdit
There is no rigorous definition of a nonmetal. Broadly, any element lacking a preponderance of metallic properties such as luster, deformability, and good electrical conductivity,[n 1] can be regarded as a nonmetal. Some variation may be encountered among authors as to which elements are regarded as nonmetals.
The fourteen elements effectively always recognized as nonmetals are hydrogen, oxygen, nitrogen, and sulfur; the corrosive halogens fluorine, chlorine, bromine, and iodine; and the noble gases helium, neon, argon, krypton, xenon, and radon.[n 2] Up to a further nine elements can be counted as nonmetals, including carbon, phosphorus, and selenium; and the elements otherwise commonly recognized as metalloids namely boron; silicon and germanium; arsenic and antimony; and tellurium, bringing the total up to twenty-three nonmetals.
Astatine, the fifth halogen, is often ignored on account of its rarity and intense radioactivity; it is here regarded as a metal.[n 3] The superheavy elements copernicium (Z = 112) and oganesson (118) may turn out to be nonmetals; their actual status is not known.[n 4]
Since there are 118 known elements, as of September 2021, the nonmetals are outnumbered by the metals several times.
Origin and use of the termEdit
The distinction between metals and nonmetals arose, in a convoluted manner, from a crude recognition of natural kinds[n 5] of matter. Thus, matter could be divided into pure substances and mixtures; pure substances eventually could be distinguished as compounds and elements; and "metallic" elements seemed to have broadly distinguishable attributes that other elements did not, such as their ability to conduct heat or for their "earths" (oxides) to form basic solutions in water, quicklime (CaO) for example. Use of the word nonmetal can be traced to as far back as Lavoisier's 1789 work Traité élémentaire de chimie in which he distinguished between simple metallic and nonmetallic substances.[n 6]
Honing the conceptEdit
Any one or more of a range of properties have been used to hone the distinction between metals and nonmetals, including:
- Physical—fusibility, malleability and ductility; opacity; bulk coordination number; minimum excitation potential; sonorousness; physical state; critical temperature; Goldhammer-Herzfeld metallicity criterion ratio; enthalpy of vaporization; liquid range; temperature coefficient of resistivity; atomic conductance; packing efficiency; 3D electrical conductivity; electrical conductivity at absolute zero; thermal conductivity;
- Chemical—cation formation; acid-base character of oxides; sulfate formation; oxide solubility in acids; or
Johnson noted that physical properties can best indicate the metallic or nonmetallic properties of an element, with the proviso that other properties will be needed in a number of ambiguous cases.
Kneen at al. added that:
- "It is merely necessary to establish and apply a criterion of metallicity…many arbitrary classifications are possible, most of which, if chosen reasonably, would be similar, but not necessarily identical…the relevance of the criterion can only be judged by the usefulness of the related classification."
Once a basis for distinguishing between the "two great classes of elements" is established, the nonmetals are found to be those lacking the properties of metals, to greater or lesser degrees.
|B 38||C 17|
|Al 74||Si 34||S 19|
|Ga 39||Ge 34||As 38||Se 24||Br 15|
|In 68||Sn 53||Sb 41||Te 36||I 24|
|Tl 74||Pb 74||Bi 43||Po 53||At 74|
|Most metals, such as those in a gray cell,[n 8] have close-packed centro-symmetrical structures featuring metallic bonding and a packing efficiency of at least 68%.[n 9] Nonmetals, and some nearby metals (Ga, Sn, Bi, Po) have more open-packed directional structures featuring either covalent or partial covalent bonding and, subsequently, lower packing densities.|
Physically, nonmetals in their most stable forms exist as either polyatomic solids (carbon, for example) with open-packed forms; diatomic molecules such as hydrogen (a gas) and bromine (a liquid); or monatomic gases (such as neon). They usually have small atomic radii. Metals, in contrast, are nearly all solid and close-packed, and mostly have larger atomic radii. Other than sulfur, solid nonmetals have a submetallic appearance and are brittle, as opposed to metals, which are lustrous, and generally ductile or malleable. Nonmetals usually have lower densities than metals; are mostly poorer conductors of heat and electricity; and tend to have significantly lower melting points and boiling points.
The physical differences between metals and nonmetals arise from internal and external atomic forces. Internally, an atom's nuclear charge acts to hold its valence electrons in place. Externally, the same electrons are subject to attractive forces from the nuclear charges in nearby atoms. When the external forces are greater than, or equal to, the internal force, valence electrons are expected to become itinerant and metallic properties are predicted. Otherwise nonmetallic properties are anticipated.
Chemically, nonmetals mostly have higher ionization energies, higher electron affinities,[n 10] higher electronegativity values, and higher standard reduction potentials than metals. Here, and in general, the higher an element's ionization energy, electron affinity, electronegativity, or standard reduction potentials, the more nonmetallic that element is.
In chemical reactions, nonmetals tend to gain or share electrons unlike metals which tend to donate electrons. More specifically, and given the stability of the noble gases, nonmetals generally gain a number of electrons sufficient to give them the electron configuration of the following noble gas whereas metals tend to lose electrons sufficient to leave them with the electron configuration of the preceding noble gas.[n 11] For nonmetallic elements this tendency is encapsulated by the duet and octet rules of thumb (and for metals there is a less rigorously followed 18-electron rule). A key attribute of nonmetals is that they never form basic oxides; their oxides are generally acidic. Moreover, solid nonmetals (including metalloids) react with nitric acid to form an oxide (carbon, silicon, sulfur, antimony, and tellurium) or an acid (boron, phosphorus, germanium, selenium, arsenic, iodine).
|Exist as anions
or oxyanions[n 12]
|Exist as cations|
|Negative or positive||Positive|
|Metallic between metals|
(via alloy formation)
|Ionic between nonmetals and metals|
|Oxides||Acidic||Basic in lower oxides;|
in higher oxides
The chemical differences between metals and nonmetals largely arise from the attractive force between the positive nuclear charge of an individual atom and its negatively charged valence electrons. From left to right across each period of the periodic table the nuclear charge increases as the number of protons in the core increases. There is an associated reduction in atomic radius as the increasing nuclear charge draws the valence electrons closer to the core. In metals, the nuclear charge is generally weaker than that of nonmetallic elements. In chemical bonding, metals therefore tend to lose electrons, and form positively charged or polarized atoms or ions whereas nonmetals tend to gain those same electrons due to their stronger nuclear charge, and form negatively charged ions or polarized atoms.
The number of compounds formed by nonmetals is vast. The first nine places in a "top 20" table of elements most frequently encountered in 8,427,300 compounds, as listed in the Chemical Abstracts Service register for July 1987, were occupied by nonmetals. Hydrogen, carbon, oxygen and nitrogen were found in the majority (greater than 64%) of compounds. Silicon, a metalloid, was in 10th place. The highest rated metal, with an occurrence frequency of 2.3%, was iron, in 11th place. Examples of nonmetal compounds are: boric acid H
3, used in ceramic glazes; selenocysteine; C
2Se, the 21st amino acid of life; phosphorus sesquisulfide (P4S3), in strike anywhere matches; and teflon (C
Complicating the chemistry of the nonmetals are the anomalies seen in the first row of each periodic table block, particularly in hydrogen, (boron), carbon, nitrogen, oxygen and fluorine; secondary periodicity or non-uniform periodic trends going down most of the p-block groups; and unusual valence states in the heavier nonmetals.
First row anomaly. The first row anomaly largely arises from the electron configurations of the elements concerned. Hydrogen is noted for the different ways it forms bonds. It most commonly forms covalent bonds. It can lose its single valence electron in aqueous solution, leaving behind a bare proton with tremendous polarizing power. This subsequently attaches itself to the lone electron pair of an oxygen atom in a water molecule, thereby forming the basis of acid-base chemistry. A hydrogen atom in a molecule can form a second, weaker, bond with an atom or group of atoms in another molecule. Such bonding, "helps give snowflakes their hexagonal symmetry, binds DNA into a double helix; shapes the three-dimensional forms of proteins; and even raises water's boiling point high enough to make a decent cup of tea."
From boron to neon, since the 2p subshell has no inner analogue and experiences no electron repulsion effects it has a relatively small radius, unlike the 3p, 4p and 5p subshells of heavier elements.[n 13] Ionization energies and electronegativities among these elements are consequently higher than would otherwise be expected, having regard to periodic trends. The small atomic radii of carbon, nitrogen, and oxygen facilitate the formation of triple or double bonds.
Secondary periodicity. Immediately after the first row of the transition metals, the 3d electrons in the 4th row of periodic table elements, i.e. in gallium (a metal), germanium, arsenic, selenium, and bromine, are not as effective at shielding the increased nuclear charge. The net result, especially for the group 13–15 elements, is that there is an alternation in some periodic trends going down groups 13 to 17.[n 14]
Unusual valence states. The larger atomic radii of the heavier group 15–18 nonmetals enable higher bulk coordination numbers, and result in lower electronegativity values that better tolerate higher positive charges. The elements involved are thereby able to exhibit valences other than the lowest for their group (that is, 3, 2, 1, or 0) for example in phosphorus pentachloride (PCl5), sulfur hexafluoride (SF6), iodine heptafluoride (IF7), and xenon difluoride (XeF2).
Approaches to classifying nonmetals may involve from as few as two subclasses to up to six or seven. For example, the Encyclopedia Britannica periodic table has noble gases, halogens, and other nonmetals, and splits the elements commonly recognized as metalloids between the "other metals" and the "other nonmetals"; the Royal Society of Chemistry periodic table shows the nonmetallic elements as occupying seven groups.
From right to left in periodic table terms, three or four kinds of nonmetals are more or less commonly discerned.[n 17] These are:
- the relatively inert noble gases;
- a set of chemically strong halogen elements—fluorine, chlorine, bromine and iodine—sometimes referred to as nonmetal halogens (the term used here) or stable halogens;
- a set of unclassified nonmetals, including elements such as hydrogen, carbon, nitrogen, and oxygen, with no widely recognized collective name; and
- the chemically weak nonmetallic metalloids, sometimes considered to be nonmetals and sometimes not.[n 18]
Since the metalloids occupy frontier territory, where metals meet nonmetals, their treatment varies from author to author. Some consider them separate from both metals and the nonmetals; some regard them as nonmetals or as a sub-class of nonmetals; others count some of them as metals, for example, arsenic and antimony due to their similarities with heavy metals.[n 19] Metalloids are here treated as nonmetals in light of their chemical behavior, and for comparative purposes.
Aside from the metalloids, some boundary fuzziness and overlapping (as occurs with classification schemes generally) can be discerned among the other nonmetal subclasses. Carbon, phosphorus, selenium, iodine border the metalloids and show some metallic character, as does hydrogen. Among the noble gases, radon is the most metallic and begins to show some cationic behavior, which is unusual for a nonmetal.
|Atomic radii (Å), periods 2 to 4 [n 20]|
|Span||2.05 to 2.31||1.9 to 2.24||1.63 to 2.19||1.56 to 2.12|
|Ionization energy (kJ mol−1)|
|Span||768 to 953||947 to 1,320||1,015 to 1,687||1,037 to 2,372|
|Electron affinity (kJ mol−1)|
|Span||27 to 190||−0.07 to 200||295 to 349||−120 to −50|
|Span||1.9 to 2.18||2.19 to 3.44||2.66 to 3.98||2.1 to 5.2|
|Standard reduction potential (V)|
|Span||−0.91 to 0.93||0.00 to 2.08||0.53 to 2.87||2.12 to 2.26|
|Goldhammer-Herzfeld criterion ratio (unit less)|
|Average values of atomic radius, ionization energy, electron affinity, electronegativity,[n 22] and standard reduction potential generally show a left to right increase consistent with increased nonmetallic character.|
Electron affinity values collapse at the noble gases due to their filled outer orbitals. Electron affinity can be defined as, "the energy required to remove the electron of a gaseous anion of −1 charge to produce a gaseous atom of that element e.g. Cl−(g) → e− = 348.8 kJ mol−1"; the zeroth ionization energy, in other words.
The standard reduction potentials are for stable species in water, at pH 0, within the range −3 to 3 V. The values in the noble gas column are for xenon only.
The Goldhammer-Herzfeld ratio  is an approximate (non-relativistic) measure of how metallic an element is, metals having values ≥ 1. It quantifies the explanation given for the differences between metals and nonmetals set out at the end of the Properties section.[n 23]
Six nonmetals are classified as noble gases: helium, neon, argon, krypton, xenon, and the radioactive radon. In conventional periodic tables they occupy the rightmost column. They are called noble gases in light of their characteristically very low chemical reactivity.
They have very similar properties, all being colorless, odorless, and nonflammable. With their closed valence shells the noble gases have feeble interatomic forces of attraction resulting in very low melting and boiling points. That is why they are all gases under standard conditions, even those with atomic masses larger than many normally solid elements.
Chemically, the noble gases have relatively high ionization energies, nil or negative electron affinities, and relatively high electronegativities. Compounds of the noble gases number in the hundreds although the list continues to grow, with most of these occurring via oxygen or fluorine combining with either krypton, xenon or radon.
While the nonmetal halogens are corrosive and markedly reactive elements, they can be found in such innocuous compounds as ordinary table salt NaCl. Their remarkable chemical activity as nonmetals can be contrasted with the equally remarkable chemical activity of the alkali metals such as sodium and potassium, located at the far left of the periodic table.[n 24]
Physically, fluorine and chlorine are pale yellow and yellowish green gases; bromine is a reddish-brown liquid; and iodine is a silvery metallic solid.[n 25] Electrically, the first three are insulators while iodine is a semiconductor (along its planes).
Chemically, they have high ionization energies, electron affinities, and electronegativity values, and are mostly relatively strong oxidizing agents. Manifestations of this status include their intrinsically corrosive nature. All four exhibit a tendency to form predominately ionic compounds with metals whereas the remaining nonmetals, bar oxygen, tend to form predominately covalent compounds with metals.[n 26] The reactive and strongly electronegative nature of the nonmetal halogens represents the epitome of nonmetallic character.
After the nonmetallic elements are classified as either noble gases, halogens or metalloids (following), the remaining seven nonmetals are hydrogen, carbon, nitrogen, oxygen, phosphorus, sulfur and selenium. Three are colorless gases (H, N, O); three have a metal-like appearance (C, P, Se);[n 28] and one is yellow (S). Electrically, graphitic carbon is a semimetal (along its planes);[n 29] phosphorus and selenium are semiconductors; and hydrogen, nitrogen, oxygen, and sulfur are insulators.[n 30]
They are generally regarded as being too diverse to merit a collective examination, and have been referred to as other nonmetals, or more plainly as nonmetals, located between metalloids and halogens. Consequently, their chemistry tends to be taught disparately, according to their four respective periodic table groups, for example: hydrogen in group 1; the group 14 carbon nonmetals (carbon, and possibly silicon and germanium); the group 15 pnictogen nonmetals (nitrogen, phosphorus, and possibly arsenic and antimony); and the group 16 chalcogen nonmetals (oxygen, sulfur, selenium, and possibly tellurium). Other subdivisions are possible according to the individual preferences of authors.[n 31]
Hydrogen, in particular, behaves in some respects like a metal and in others like a nonmetal. Like a metal it can (first) lose its single valence electron; it can stand in for alkali metals in typical alkali metal structures; and is capable of forming alloy-like hydrides, featuring metallic bonding, with some transition metals. On the other hand, it is an insulating diatomic gas, like a typical nonmetal, and in chemical reactions more generally, it has a tendency to attain the electron configuration of helium. It does this by way of forming a covalent or ionic bond or, if its has lost its valence electron, attaching itself to a lone pair of electrons.
Some or all of these nonmetals nevertheless have several shared properties. Their physical and chemical character is "moderately non-metallic", on a net basis. Being less reactive than the halogens, most of them, except for phosphorus, can occur naturally in the environment. They have prominent biological and geochemical aspects. When combined with halogens, unclassified nonmetals form (polar) covalent bonds. When combined with metals they can form hard (interstitial or refractory) compounds, in light of their relatively small atomic radii and sufficiently low ionization energy values. Unlike the halogens, unclassified nonmetals show a tendency to catenate, especially in solid-state compounds. Diagonal relationships among these nonmetals echo similar relationships among the metalloids.[n 32]
In periodic table terms, a geographic analogy is seen between the unclassified nonmetals and transition metals. The unclassified nonmetals occupy territory between the strongly nonmetallic halogens on the right and the weakly nonmetallic metalloids on the left. The transition metals occupy territory, "between the 'virulent and violent' metals on the left of the periodic table, and the 'calm and contented' metals to the right...[and]...form "a transitional bridge between the two".
The six elements more commonly recognized as metalloids are boron, silicon, germanium, arsenic, antimony, and tellurium, with each having a metal appearance.[n 33] On a standard periodic table, they occupy a diagonal area in the p-block extending from boron at the upper left to tellurium at lower right, along the dividing line between metals and nonmetals shown on some periodic tables.
They are brittle and only fair conductors of electricity and heat. Boron, silicon, germanium, tellurium are semiconductors. Arsenic and antimony have the electronic band structures of semimetals although both have less stable semiconducting allotropes.
Chemically the metalloids generally behave like (weak) nonmetals. Among the nonmetallic elements they tend to have the lowest ionization energies, electron affinities, and electronegativity values; and are relatively weak oxidizing agents. They further demonstrate a tendency to form alloys with metals.
Like hydrogen among the unclassified nonmetals, boron is chemically similar to metals in some respects.[n 34] It has fewer electrons than orbitals available for bonding. Analogies with transition metals occur in the formation of complexes, and adducts (for example, BH3 + CO →BH3CO and, similarly, Fe(CO)4 + CO →Fe(CO)5),[n 35] as well as in the geometric and electronic structures of cluster species such as [B6H6]2− and [Ru6(CO)18]2−.
To the left of the weakly nonmetallic metalloids, in periodic table terms, are found an indeterminate set of weakly metallic metals (such as tin, lead and bismuth) sometimes referred to as post-transition metals.
Properties of metals and those of the (sub)classes of metalloids, unclassified nonmetals, nonmetal halogens, and noble gases are summarized in the following two tables. Physical properties apply to elements in their most stable forms in ambient conditions, unless otherwise specified, and are listed in loose order of ease of determination. Chemical properties are listed from general to specific, and then to descriptive. The dashed line around the metalloids denotes that, depending on the author, the elements involved may or may not be recognized as a distinct class or subclass of elements. Metals are included as a reference point.
|Some cross-subclass physical properties|
|Physical property||Metals||Metalloids||Unclassified nonmetals||Nonmetal halogens||Noble gases|
|Alkali, alkaline earth, lanthanide, actinide, transition and post-transition metals||Boron, silicon, germanium, arsenic, antimony (Sb), tellurium||Hydrogen, carbon, nitrogen, phosphorus, oxygen, sulfur, selenium||Fluorine, chlorine, bromine, iodine||Helium, neon, argon, krypton, xenon, radon|
|Form||solid (Hg is liquid)||solid||solid: C, P, S, Se
gaseous: H, N, O
gaseous: F, Cl
|Appearance||lustrous||semi-lustrous||semi-lustrous: C, P, Se
colorless: H, N, O
|colored: F, Cl, Br
|Elasticity||mostly malleable and ductile (Hg is liquid)||brittle||• C, black P, S and Se are brittle
• the same four have less stable non-brittle forms[n 36]
|iodine is brittle||not applicable|
|Structure||mainly close-packed centrosymmetrical||polyatomic||polyatomic: C, P, S, Se
diatomic: H, N, O
|Bulk coordination number||mostly 8−12, or more||6, 4, 3, or 2||3, 2, or 1||1||0|
|Allotropes||• common with temperature or pressure changes||all form||known for C, P, O, S, Se||iodine is known in amorphous form
|Electrical conductivity||high[n 37]||moderate: B, Si, Ge, Te
high: As, Sb[n 38]
|low: H, N, O, S
moderate: P, Se
high: C[n 39]
|low: F, Cl, Br
moderate: I[n 40]
|Volatility[n 42]||• low
• Hg is the most volatile in its class
• As is lowest in class
|low: C, P, S, Se
high: H, N, O
|Electronic structure||metallic (Bi is a semimetal)||semimetal (As, Sb) or semiconductor||semimetal (C), semiconductor (P, Se) or insulator (H, N, O, S)||semiconductor (I) or insulator||insulator|
|Outer electrons||1–8 valence||3–6||4–6 (H has 1)||7||8 (He has 2)|
|Crystal structure[n 43]||mainly cubic or hexagonal||rhombohedral: B, As, Sb
cubic: Si, Ge
|cubic: P, O
hexagonal: H, C, N, Se
orthorhombic: Cl, Br, I
|cubic: Ne, Ar, Kr, Xe, Rn|
|Some cross-subclass chemical properties|
|Chemical property||Metals||Metalloids||Unclassified nonmetals||Nonmetal halogens||Noble gases|
|Alkali, alkaline earth, lanthanide, actinide, transition and post-transition metals||Boron, silicon, germanium, arsenic, antimony (Sb), tellurium||Hydrogen, carbon, nitrogen, phosphorus, oxygen, sulfur, selenium||Fluorine, chlorine, bromine, iodine||Helium, neon, argon, krypton, xenon, radon|
|General chemical behavior||• strong to weakly metallic
• noble metals are disinclined to react
|weakly nonmetallic[n 45]||moderately nonmetallic[n 46]||strongly nonmetallic||• inert to nonmetallic|
• Rn shows some cationic behavior
|Ionization energy‡||• relatively low
• higher for noble metals
• ionization energy for Hg and possibly Rg, Ds, Cn[n 47] exceed those for some nonmetals
• electronegativity values of noble metals exceed that of P
|moderate||moderate to high||high||high to very high|
|Electron affinity‡||moderate||moderate: H, C, O, P (N is c. zero)
• higher: S, Se
|high||zero or less|
Si < Ge ≈ B ≈ Sb < Te < As
|moderate (P) to high:
P < Se ≈ C < S < N < O
I < Br < Cl < F
|moderate (Rn) to very high|
|moderate||moderate to high||high||high for Xe|
|Non-zero oxidation states||• largely positive
• negative anionic states known for most alkali and alkaline earth metals; Pt, Au
|negative and positive known for all||• negative states known for all, but for H this is an unstable state
• positive known for all but only exceptionally for F and O
• from −5 for B to +7 for Cl, Br, I, and At
|• only positive oxidation states known, and only for heavier noble gases|
• from +2 for Kr, Xe, and Rn to +8 for Xe
|Catenation tendency||known for group 8‒11 transition metals; and Hg, Ga, In, Sn and Bi||• significant: B, Si; Te
• less so: Ge, As, Sb
significant: P, S, Se
less so: H, N, O
|known in cationic (Cl, Br, I) and anionic forms||not known; no catenation reported|
|Biological interactions (human life)[n 49]||• 17% of naturally occurring metals are essential in major or trace quantities
• Most heavier metals, including Cr, Cd, Hg and Pb, are known for their toxicity
|• 33% (two of six) are essential trace elements: B, Si[n 50]
• As is noted for its toxicity
|• 100% are essential: H, C, N, O form the basis for life; P and S are major elements;[n 51] Se occurs in selenocysteine, the 21st amino acid of life, as a trace element
• O, P and Se are potentially toxic[n 52]
|• 100% are essential: Cl as a major constituent; F, Br, I as trace elements
• corrosive in their elemental forms
|• 0% essential|
• He is used in respiratory medicine and diving gas mixtures; Ar has been used in human studies, while Xe has several medical uses; Rn was formerly used to treat tumours
|Compounds with metals||alloys or intermetallic compounds||tend to form alloys or intermetallic compounds||• salt-like to covalent: H†, C, N, P, S, Se
• mainly ionic: O
|mainly ionic: F, Cl, Br, I||simple compounds in ambient conditions not known[n 53]|
|Oxides||• ionic, polymeric, layer, chain, and molecular structures
• V; Mo, W; Al, In, Tl; Sn, Pb; Bi are glass formers
• basic; some amphoteric or acidic
|• polymeric in structure
• B, Si, Ge, As, Sb, Te are glass formers
• amphoteric or weakly acidic[n 54]
|• mostly molecular
• C, P, S, Se are known in at least one polymeric form
• P, S, Se are glass formers; CO2 forms a glass at 40 GPa
• acidic (NO
3, and SeO
3 strongly so) or neutral (H2O, CO, NO, N2O)[n 55]
• iodine is known in at least one polymeric form, I2O5
• no glass formers reported
• acidic; ClO
7, and I
5 strongly so
• XeO2 is polymeric
• no glass formers reported
• metastable XeO3 is acidic; stable XeO4 strongly so
|Reaction with conc. nitric acid||most form nitrates||• B forms boric acid; As forms arsenic acid
• Si, Ge, Sb, and Te form oxides
|• C, S form oxides
• P, Se form phosphoric acid, and selenic acid
|• F forms nitroxyfluoride NO3F
• I forms iodic acid
|nil; no reaction reported|
|Reaction with conc. sulfuric acid||most form sulfates[n 56][n 57]||• B forms boric acid
• Si does not react
• Ge, Sb form sulfates
• As forms an oxide
• Te forms the sulfoxide TeSO3
|• C, S form oxides
• P (red) forms phosphoric acid
• Se forms the sulfoxide SeSO3
|• iodine can form a polymeric yellow sulfate (IO)2SO4 in the presence of I2O5||nil; no reaction reported|
|† Hydrogen can also form alloy-like hydrides|
‡ The labels moderate, high, higher, and very high are based on the value spans listed in the table "Property spans and average values for the subclasses of nonmetallic elements"
Most nonmetallic elements exist in allotropic forms. Carbon, for example, occurs as graphite and as diamond. Such allotropes may exhibit physical properties that are more metallic or less nonmetallic.
Among the nonmetal halogens, and unclassified nonmetals:
- Iodine is known in a semiconducting amorphous form.
- Graphite, the standard state of carbon, is a fairly good electrical conductor. The diamond allotrope of carbon is clearly nonmetallic, being translucent, and an extremely poor electrical conductor. Carbon is further known in several other allotropic forms, including semiconducting buckminsterfullerene (C60).
- Nitrogen can form gaseous tetranitrogen (N4), an unstable polyatomic molecule with a lifetime of about one microsecond.
- Oxygen is a diatomic molecule in its standard state; it also exists as ozone (O3), an unstable nonmetallic allotrope with a half-life of around half an hour.
- Phosphorus, uniquely, exists in several allotropic forms that are more stable than that of its standard state as white phosphorus (P4). The white, red and black allotropes are probably the best known; the first is an insulator; the latter two are semiconductors. Phosphorus also exists as diphosphorus (P2), an unstable diatomic allotrope.
- Sulfur has more allotropes than any other element. Amorphous sulfur, a metastable mixture of such allotropes, is noted for its elasticity.
- Selenium has several nonmetallic allotropes, all of which are much less electrically conducting than its standard state of gray "metallic" selenium.[n 58]
All the elements most commonly recognized as metalloids form allotropes. Boron is known in several crystalline and amorphous forms. The discovery of a quasi-spherical allotropic molecule, borospherene (B40), was announced in 2014. Silicon was most recently known only in its crystalline and amorphous forms. The synthesis of an orthorhombic allotrope, Si24, was subsequently reported in 2014. At a pressure of c. 10–11 GPa, germanium transforms to a metallic phase with the same tetragonal structure as tin; when decompressed—and depending on the speed of pressure release—metallic germanium forms a series of allotropes that are metastable in ambient conditions. Arsenic and antimony form several well-known allotropes (yellow, grey, and black). Tellurium is known in its crystalline and amorphous forms.
Other allotropic forms of nonmetallic elements are known, either under pressure or in monolayers. Under sufficiently high pressures, at least half of the nonmetallic elements that are semiconductors or insulators,[n 59] starting with phosphorus at 1.7 GPa, have been observed to form metallic allotropes.[n 60] Single layer two-dimensional forms of nonmetals include borophene (boron), graphene (carbon), silicene (silicon), phosphorene (phosphorus), germanene (germanium), arsenene (arsenic), antimonene (antimony) and tellurene (tellurium), collectively referred to as "xenes".
Abundance, occurrence, extraction and costEdit
Hydrogen and helium are estimated to make up approximately 99% of all ordinary matter in the universe and over 99.9% of its atoms. Oxygen is thought to the next most abundant element, at c. 0.1%. Less than five percent of the universe is believed to be made of ordinary matter, represented by stars, planets and living beings. The balance is made of dark energy and dark matter, both of which are currently poorly understood.
Hydrogen, carbon, nitrogen, and oxygen constitute the great bulk of the Earth's atmosphere, oceans, crust, and biosphere; the remaining nonmetals have abundances of 0.5% or less. In comparison, 35% of the crust is made up of the metals sodium, magnesium, aluminium, potassium and iron; together with a metalloid, silicon. All other metals and metalloids have abundances within the crust, oceans or biosphere of 0.2% or less.
About 1015 tonnes of noble gases are present in the Earth's atmosphere. Helium is additionally found in natural gas to the extent of as much as 7%. Radon further diffuses out of rocks, where it is formed during the natural decay sequence of uranium and thorium. In 2014, it was reported that the Earth's core may contain c. 1013 tons of xenon, in the form of stable XeFe3 and XeNi3 intermetallic compounds. This may explain why "studies of the Earth's atmosphere have shown that more than 90% of the expected amount of Xe is depleted."
The nonmetal halogens are found in salt-related minerals. Fluorine occurs in fluorite, this being a widespread mineral. Chlorine, bromine and iodine are found in brines. Exceptionally, a 2012 study reported the presence of 0.04% native fluorine (F
2) by weight in antozonite, attributing these inclusions to radiation from the presence of tiny amounts of uranium.
Unclassified nonmetals occur typically occur in elemental forms (oxygen, sulfur) or are found in association with either of these two elements.
- Hydrogen occurs in the world's oceans as a component of water, and in natural gas as a component of methane and hydrogen sulfide.
- Carbon, as graphite, mainly occurs in metamorphic silicate rocks as a result of the compression and heating of sedimentary carbon compounds.
- Oxygen is found in the atmosphere; in the oceans as a component of water; and in the crust as oxide minerals.
- Phosphorus minerals are widespread, usually as phosphorus-oxygen phosphates.
- Elemental sulfur can be found near hot springs and volcanic regions in many parts of the world; sulfur minerals are widespread, usually as sulfides or oxygen-sulfur sulfates.
- Selenium occurs in metal sulfide ores, where it partially replaces the sulfur; elemental selenium is occasionally found.
The metalloids tend to be found in forms combined with oxygen or sulfur or, in the case of tellurium, gold or silver. Boron is found in boron-oxygen borate minerals including in volcanic spring waters. Silicon occurs in the silicon-oxygen mineral silica (sand). Germanium, arsenic and antimony are mainly found as components of sulfide ores. Tellurium occurs in telluride minerals of gold or silver. Native forms of arsenic, antimony and tellurium have been reported.
Nonmetals, and metalloids, are extracted in their raw forms from:
- brine—chlorine, bromine, iodine;
- liquid air—nitrogen, oxygen, neon, argon, krypton, xenon;
- minerals—boron (borate minerals); carbon (coal; diamond; graphite); fluorine (fluorite); silicon (silica); phosphorus (phosphates); antimony (stibnite, tetrahedrite); iodine (in sodium iodate and sodium iodide);
- natural gas—hydrogen, helium, sulfur; and
- ores, as processing byproducts—germanium (zinc ores); arsenic (copper and lead ores); selenium, tellurium (copper ores); and radon (uranium-bearing ores).
While non-radioactive nonmetals are relatively inexpensive, there are some exceptions. As of July 2021[update], boron, germanium, arsenic, and bromine can cost from $3–10 US per gram (cf. silver at about $1 per gram). Prices can fall dramatically if bulk quantities are involved. Black phosphorus is produced only in gram quantities by boutique suppliers—a single crystal produced via chemical vapor transport can cost up to $1,000 US per gram (ca. seventeen times the cost of gold); in contrast, red phosphorus costs about 50 cents a gram or $227 a pound. Up to 2013, radon was available from the National Institute of Standards and Technology for $1,636 per 0.2 ml unit of issue, equivalent to c. $86,000,000 per gram (with no indication of a discount for bulk quantities).
|air replacements (inert)||H, He, C, N, O, F (in SF6), P, S and Ar|
|cryogenics and refrigerants||H, He, N, O, F, Ne, S, Cl and Ar|
|fertilizers||H, B, C, N, O, Si, P, S|
|flame retardants or fire extinguishers||H, B, C (including graphite), N, O, F, Si, P, S, Cl, Ar, Br and Sb|
|household accoutrements[n 61]||H (primary constituent of water); He (party balloons); B (in detergents); C (in pencils, as graphite); N (beer widgets); O (as peroxide, in detergents); F (as fluoride, in toothpaste); Ne (lighting); Si (in glassware); P (matches); S (garden treatments); Cl (bleach constituent); Ar (insulated windows); Ge (in wide-angle camera lenses); Se (glass; solar cells); Br (as bromide, for purification of spa water); Kr (energy saving fluorescent lamps); Sb (in batteries); Te (in ceramics, solar panels, rewrite-able DVDs); I (in antiseptic solutions); Xe (in plasma TV display cells, a technology subsequently made redundant by low cost LED and OLED displays)|
|lasers and lighting||H, He, C (in carbon dioxide lasers, CO2); N, O (in a chemical oxygen iodine laser); F (in a hydrogen fluoride laser, HF); Ne, Si, P, S (in a sulfur lamp); Cl, Ar, Ge, As, Se, Br, Kr, Te, I and Xe|
|medicine and pharmaceuticals||H, He, B, C, N, O, F, Si, P, S, Cl, Ar, As, Se, Br, Kr, Sb, Te, I, Xe and Rn|
|mineral acids||H, B, C, N, O, F, Si, P, S, Cl, Ge, As, Sb, Br, Te, I and Xe|
|plug-in hybrid vehicles||H, He, B, C, N, O, F, Si, P, S, Cl, Ar, Br, Sb, Te and I|
|welding gases||H, He, C (in CO2), N, O, Ar|
|smart phones||H, He, B, C, N, O, F, Si, P, S, Cl, Ge, As, Se, Br, Sb|
Near universal uses for nonmetals are for household accoutrements; lasers and lighting; and medicine and pharmaceuticals. One or two of germanium, arsenic, and or radon will be absent. In a like manner, most metals have structural uses. To the extent that metalloids show metallic character, they have speciality uses extending to (for example) oxide glasses, alloying components, and semiconductors.
Further shared uses of different subsets of the nonmetals encompass their presence in, or specific uses in the fields of air replacements (inert); cryogenics and refrigerants; fertilizers; flame retardants or fire extinguishers; mineral acids; plug-in hybrid vehicles; welding gases; and smart phones.
Cylinders containing argon gas for use in extinguishing fire without damaging computer server equipment
Most nonmetallic elements were not discovered until after Hennig Brand isolated phosphorus from urine in 1669. Before then, carbon, sulfur and antimony were known in antiquity, and arsenic was discovered during the Middle Ages (by Albertus Magnus). The remainder were isolated in the 18th and 19th centuries. Helium (1868), was the first element not discovered on Earth.[n 62] Radon was discovered at the end of the 19th century.
Arsenic, phosphorus and nonmetallic elements subsequently discovered were isolated using one or more of the tools of chemists or physicists namely spectroscopy; fractional distillation; radiation detection; electrolysis; adding acid to an ore; combustion; displacement reactions; or heating:
- Of the noble gases, helium was detected via its yellow line in the coronal spectrum of the sun, and later by observing the bubbles escaping from uranite UO2 dissolved in acid; neon through xenon were obtained via fractional distillation of air; and radioactive radon was observed emanating from compounds of thorium, four years after the discovery of radiation, in 1895, by Henri Becquerel.
- The nonmetal halogens were obtained from their halides, either via electrolysis; adding an acid; or displacement. Some chemists died as a result of their experiments trying to isolate fluorine.
- Among unclassified nonmetals, nitrogen was observed in air from which oxygen had been removed; oxygen was obtained by heating mercurous oxide; phosphorus was liberated by heating ammonium sodium hydrogen phosphate Na(NH4)HPO4, as found in urine; and selenium[n 63] was detected as a residue in sulfuric acid.
- It is usually considered characteristic of nonmetals that they have a negative temperature coefficient of resistivity, in which electrical resistance falls with rising temperature. The converse nearly always holds true for metals: their resistivity increases with rising temperature. Plutonium is an exception. Its electrical resistivity falls when heated in the temperature range of around –175 to +125 °C. The divalent metals barium, europium and ytterbium, in liquid form, likewise exhibit a negative temperature coefficient of resistivity.
- The elements commonly recognised as metalloids are boron, silicon, germanium, arsenic, antimony and tellurium. Rochow observed that it is sometimes desirable to think of carbon, phosphorus and selenium as metalloids. These three elements have been referred to as near metalloids. The remaining nonmetallic elements are hydrogen, oxygen, nitrogen, sulfur, the four nonmetal halogens, and the noble gases.
- The bulk properties of astatine remain unknown as a visible quantity of it would immediately self-vaporize from the heat generated by its radioactivity. It remains to be seen if, with sufficient cooling, a macroscopic quantity could be deposited as a thin film.
Qualitative and quantitive assessments of the status of astatine, including having regard to relativistic effects, have been consistent with it being a metal:
- 1940: Astatine was judged to be a metal when it was first synthesized. That assessment was consistent with some metallic character seen in iodine, its lighter halogen congener.
- 1972: Batsanov calculated astatine would have a band gap of 0.7 eV (but see the 2013 entry).
- 1983: Edwards and Sienko speculated that, on the basis of the non-relativistic Goldhammer-Herzfeld criterion for metallicity, astatine was probably a metalloid. As the ratio is based on classical arguments it does not accommodate the finding that polonium (cf. 2006 entry following) adopts a metallic (rather than covalent) crystalline structure, on relativistic grounds. Even so it offers a first order rationalization for the occurrence of metallic character amongst the elements.
- 2002: Siekierski and Burgess presumed astatine would be a metal in the context of some of the properties of iodine.
- 2006: Restrepo et al., on the basis of a comparative study of 128 known and interpolated physiochemical, geochemical and chemical properties of 72 of the elements, reported that astatine appeared to share more in common with polonium (a metal) than it did with the established halogens and that, "At should not be considered as a halogen." In so doing they echoed the 1940 observation that, "The chemical properties of the unknown substance are very close to those of polonium."
- 2010: Thornton and Burdette observed that "Since elements in heavier periods often resemble their n+1 and n-1 neighbors more than their lighter congeners, eka-iodine [astatine]...was expected to be radioactive and metallic like polonium."
- 2013: Hermann, Hoffmann, and Ashcroft predicted At would be an fcc metal, once all relativistic effects are taken into account, and that it would have a band gap of 0.68 eV (cf Batsanov) if only some of these effects were taken into account. As at 24 August 2021, they had been cited 38 times.
- For copernicium, calculations and predictions made in 2007; 2017, 2018; and 2019 have suggested it may be either a (nonmetallic) semiconductor; a noble metal; or a (nonmetallic) liquid insulator.
Oganesson, the period 7 congener of the noble gases, was originally predicted to be a noble gas but may instead be a fairly reactive metallic-looking semiconducting solid with an anomalously low first ionization potential, and a positive electron affinity, due to relativistic effects. On the other hand, if relativistic effects peak in period 7 at copernicium, oganesson may turn out to be a noble gas after all, albeit more reactive than either xenon or radon.
- A natural kind can be said to be a grouping that reflects divisions in the world, as understood at the time, rather than (so much) the interests and actions of humans. "The periodic table is considered by many authors to be a perfect illustration of how things in the world are divided into natural kinds." Since kinds are revealed by science, a science can revise which kinds it holds to exist: phlogiston was regarded as a kind until after Lavoisier's chemical revolution.
- Subſtances ſimples non-métalliques and métalliques, as Lavoisier put it.
- Bromine (15%): Packing efficiency is determined by dividing the volume of one mole of atoms by the applicable molar volume. The bond distance in solid bromine is 2.2836 Å and 2.27 ± 0.10 in the gas, giving an atomic radius r of ca. 1.14. The volume of one bromine atom is 4/3πr3. The volume of one mole of bromine atoms is given by the volume of one atom multiplied by the Avogadro's number, that is, 6.0221409×1023.
In comparison, liquid mercury has a packing efficiency of 58%.
- The figure for At is based on the expectation that it will be a monatomic metal with a close packed structure.
- Gallium, as a metal, has, "[an] odd structure [that] somewhat resembles covalently bonded Ga2 molecules within a metal lattice."
- Nitrogen and the noble gases have no or negative electron affinities.
- Exceptions can arise among the transition metals and the lanthanide and actinide metals, which have additional inner electron orbitals that may or may not participate in chemical bonding.
- including Xe and Rn to a limited extent.
- A similar effect is seen in the 1s elements, hydrogen and helium.
- The alternation in some properties is further compounded by the appearance of fourteen f-block metals between barium and hafnium.
- Hydrogen has historically been placed over one or more of lithium, boron, carbon, or fluorine; or no group at all; or all main groups simultaneously, and therefore may or may not be proximal to the bulk of unclassified nonmetals.
- These seven "strong" non-metals (N; O, S; F, Cl, Br, I) have discrete molecular structures. But for H the remaining reactive nonmetallic elements have giant covalent structures.
N, S and iodine are somewhat hobbled as "strong" nonmetals.
S reacts in the cold with alkalic and post-transition metals, and Cu, Ag and Hg, but otherwise has low values of ionization energy, electron affinity, and electronegativity compared to the averages of the others; it is regarded as being not a particularly good oxidizing agent.
Iodine is sufficiently corrosive to cause lesions resembling thermal burns, if handled without suitable protection, and tincture of iodine will smoothly dissolve Au. That said, while F, Cl and Br will all oxidize Fe2+ (aq) to Fe3+...iodine...is such a [relatively] weak oxidizing agent that it cannot remove electrons from Fe(II) ions to form Fe(III) ions." Thus, for the reaction X2 + 2e− → 2X−(aq) the reduction potentials are F +2.87 V; Cl +1.36; Br +1.09; I +0.54. Here Fe3+ + e− → Fe3+ +0.77. Thus F2, Cl2 and Br2 will oxidize Fe2+ to Fe3+ but Fe2+ will oxidize I− to I2. Iodine has previously been referred to as a moderately strong oxidizing agent.
- A basic taxonomy of nonmetals was set out in 1844, by Dupasquier, a French doctor, pharmacist and chemist. To facilitate the study of nonmetals, he wrote, "they will be divided into four groups or sections, as in the following:"
- Organogens O, N, H, C
- Sulphuroids S, Se, P
- Chloroides F, Cl, Br, I
- Boroids B, Si
- the chloroide nonmetals came to be independently referred to as halogens;
- the boroid nonmetals came to expand into the metalloids, starting from as early as 1864;
- varying configurations of the orgaonogen and the sulphuroid nonmetals have been referred to as e.g. basic nonmetals; biogens; central nonmetals; CHNOPS; essential elements; "nonmetals"; orphan nonmetals; or redox nonmetals;
- the noble gases, as a discrete grouping, were counted among the nonmetals as early as 1900.
- Tshitoyan et al. (2019) conducted a machine-based analysis of the proximity of names of the elements based on 3.3 million abstracts published between 1922 and 2018 in more than 1,000 journals. The resulting map shows that "chemically similar elements are seen to cluster together and the overall distribution exhibits a topology reminiscent of the periodic table itself." They labeled individual nonmetals as either metalloids; polyatomic nonmetals; diatomic nonmetals; halogens; or noble gases. Word proximity clusters for the metalloids, halogens, and noble gases are apparent. The remaining polyatomic (C, P, S, Se) and diatomic nonmetals (H, N, O) occupy territory between the metalloids and the nonmetal halogens.
- The elements involved may instead be classified on a case-by-case basis. For example, germanium and antimony may be counted as metals or selenium may be admitted to the metalloid club.
The considerations of authors in making these decisions may or not be made explicit and may, at times, seem arbitrary. A binary classification can facilitate the establishment of rules for determining bond types between metals and nonmetals. Alternatively, classifying some elements as metalloids "emphasizes that properties change gradually rather than abruptly as one moves across or down the periodic table". Oderberg argues on ontological grounds that anything not a metal is therefore a nonmetal, and that this includes semi-metals (i.e. metalloids).
Jones takes a more philosophical or pragmatic view. He writes: "Though classification is an essential feature of all branches of science, there are always hard cases at the boundaries. The boundary of a class is rarely sharp...Scientists should not lose sleep over the hard cases. As long as a classification system is beneficial to economy of description, to structuring knowledge and to our understanding, and hard cases constitute a small minority, then keep it. If the system becomes less than useful, then scrap it and replace it with a system based on different shared characteristics."
- Atomic radius is here defined as the average distance from the nucleus where the electron density falls to 0.001 electrons per bohr3.
- The values given in the source for C, P and Se are those for diamond; white P; and Se8. Since the values scale with density, the values used here are for a single layer of graphite (i.e. graphene) within which electron delocalization occurs in graphite; black P, the most stable form, and gray or metallic selenium, the most stable form.
- Electronegativity values for the noble gases are from Allen and Huheey
- As the ratio is based on classical arguments it does not accommodate the finding that polonium, which has a value of ~0.95, adopts a metallic (rather than covalent) crystalline structure, on relativistic grounds. Even so it offers a first order rationalization for the occurrence of metallic character amongst the elements.
- The 32-column form of periodic table is constructed by incorporating the f-block metals (green), which normally appear floating below the transition metals (blue), into the main body of the table. It has the advantage of showing all elements in their correct sequence, but it has the disadvantage of requiring more space.
- Solid iodine has a silvery metallic appearance under white light, at room temperature.
- Metal oxides are usually ionic. On the other hand, high valence oxides of metals are usually either polymeric or covalent. A polymeric oxide has a linked structure composed of multiple repeating units.
- Jones and Atkins refer to the chemically active metals of Groups 1 and 2. Elsewhere, Ambrose refers to the lanthanides and actinides as "active metals".
- C as graphite; and P as black P, the most stable form
- Graphite is a semiconductor in a direction perpendicular to its planes.
- Sulfur, an insulator, and selenium, a semiconductor are each photoconductors—their electrical conductivities increase by up to six orders of magnitude when exposed to light.
- For example, Wulfsberg divides the nonmetals, including B, Si, Ge, As, Sb, Te, Xe, into very electronegative nonmetals (Pauling electronegativity over 2.8) and electronegative nonmetals (1.9 to 2.8). This results in N and O being very electronegative nonmetals, along with the halogens; and H, C, P, S and Se being electronegative nonmetals. Se is further recognized as a semiconducting metalloid.
- Diagonal relationships encompass hydrogen (possibly), carbon, nitrogen, (oxygen), phosphorus, sulfur, selenium, and (chlorine).
Chemical similarities between hydrogen and carbon include, "comparable ionization energies, electron affinities and electronegativity values; half-filled valence shells; and correlations between the chemistry of H–H and C–H bonds."
Hydrogen and nitrogen are each, "relatively unreactive colourless diatomic gases, with comparably high ionization energies (1312.0 and 1402.3 kJ/mol), each having half-valence subshells, 1s and 2p respectively. Like the reactive azide (N−
3) anion, inter-electron repulsions in the hydride (H−) anion (with its single nuclear charge) make ionic hydrides highly reactive. Unusually for nonmetals, the two elements are known in cationic forms. In water the H+ "cation" exists as an H
6 ion, with a delocalized proton in a central OHO group. Nitrogen forms a pentazenium (N+
5) cation; bulk quantities of the salt N+
6 can be prepared. Coincidentally, the ammonium (NH+
4) cation behaves in many respects as an alkali metal anion."
"In terms of a less well-known diagonal relationship between...[oxygen and chlorine], chlorination reactions have many similarities to oxidation reactions. Such reactions tend not to be limited to thermodynamic equilibrium and often go to complete chlorination. They are often highly exothermic. Chlorine, like oxygen, forms flammable mixtures with organic compounds."
- They are called metalloids mainly in light of their metal-like appearance.
- Greenwood commented that: "The extent to which metallic elements mimic boron (in having fewer electrons than orbitals available for bonding) has been a fruitful cohering concept in the development of metalloborane chemistry ... Indeed, metals have been referred to as "honorary boron atoms" or even as "flexiboron atoms". The converse of this relationship is clearly also valid ..."
- The BH3 and Fe(CO4) species in these reactions are short-lived reaction intermediates.
- Carbon as exfoliated (expanded) graphite, and as meter-long carbon nanotube wire; phosphorus as white phosphorus (soft as wax, pliable and can be cut with a knife, at room temperature); sulfur as plastic sulfur; and selenium as selenium wires
- Metals have electrical conductivity values of from 6.9 × 103 S•cm−1 for manganese to 6.3 × 105 for silver.
- Metalloids have electrical conductivity values of from 1.5 × 10−6 S•cm−1 for boron to 3.9 × 104 for arsenic.
- Unclassified nonmetals have electrical conductivity values of from c. ~10−18 S•cm−1 for the elemental gases to 3 × 104 in graphite.
- The nonmetal halogens have electrical conductivity values of from c. ~10−18 S•cm−1 for F and Cl to 1.7 × 10−8 S•cm−1 for iodine.
- The elemental gases have electrical conductivity values of c. ~10−18 S•cm−1
- Based on vapor pressures of the elements
- At point of solidification for mercury, bromine, and gases
- The pale yellow appearance of white phosphorus is probably due to the presence of small amounts of red phosphorus
- They always give compounds less acidic in character than the corresponding compounds of the typical nonmetals
- "The elements change from...metalloids, to moderately active nonmetals, to very active nonmetals, and to a noble gas."
- Ionization energies for Ds, Rg and Cn are predictions
- While there is some variation between different electronegativity scales the Pauling scale, as refined by Allred, has become the standard.
- It needs to be borne in mind here that, "establishing evidence for the essentiality of elements is highly challenging, and often controversial."
- On the other hand, Prinessa and Sadler wrote, "As yet there is no convincing evidence that boron...is an essential element for [humans]."
- Cockell observes that C, N, O, P, S and H, "have just the right atomic size and the right number of spare electrons to allow for binding to [one another] and...some other elements, to produce a molecular soup sufficient to build a self-replicating system."
- Breathing too much oxygen will poison the brain and can lead to death; "as little as 100mg [of white phosphorus] may be a fatal dose for a human"; a 5mg dose of selenium will produce a highly toxic reaction.
- Disodium helide (Na2He) is a compound of helium and sodium that is stable at high pressures above 113 GPa. Argon forms an alloy with nickel, at 140 GPa and close to 1,500 K however at this pressure argon is no longer a noble gas.
- Arsenic trioxide reacts with sulfur trioxide, forming arsenic "sulfate" As2(SO4)3; see also the Sulfates row.
- CO and NO are, "formally the anhydrides of formic and hyponitrous acid, respectively: CO + H2O → H2CO2 (HCOOH, formic acid); N2O + H2O → H2N2O2 (hyponitrous acid)."
- See, for example, the sulfates of the transition metals, the lanthanides and the actinides.
- Sulfates of osmium have not been characterized with any great degree of certainty.
- For amorphous selenium, the increase in conductivity is a thousand-fold; for "metallic" selenium the increase is from three to as much as two-hundredfold.
- B; Si, Ge; N, P; O, S, Se, Te; nonmetal halogens; and the noble gases
- As at 2020, high pressure studies and experiments were said to represent, "a very active and vigorous research field".
- Radon sometimes occurs as potentially hazardous indoor pollutant
- Helium acquired the "-ium" suffix as its discoverer, William Lockyer, wrote: "I took upon myself the responsibility of coining the word helium.... I did not know whether the substance ... was a metal like calcium or a gas like hydrogen, but I did know that it behaved like hydrogen [being found in the sun] and that hydrogen, as Dumas had stated, behaved as a metal."
- Berzelius, who discovered selenium, thought it had the properties of a metal, combined with those of sulfur.
- It is conjectured that Albert Magnus heated a combination of arsenic trioxide with either vegetable oil or charcoal.
- The tellurium oxide was derived from a tellurium ore containing 92.6% Te, 7.2% Fe, and 0.2% Au. Weeks explains what happened:
- "After digesting the ore with aqua regia, he [Klaproth] filtered off the residue and diluted the filtrate slightly with water. When he made the solution alkaline with caustic potash, a white precipitate appeared, but this dissolved in excess alkali, leaving only a brown, flocculent deposit containing gold and hydrous ferric oxide. Klaproth removed this precipitate by filtration and added hydrochloric acid to the filtrate until it was exactly neutral. A copious precipitate appeared [tellurium dioxide]. After washing and drying it he stirred it up with oil and introduced the oil paste into a glass retort; which he gradually heated to redness. When he cooled the apparatus, he found metallic globules of tellurium in the receiver and retort."
- Schenk & Prins 1953, p. 957
- Deming 1923, p. 544
- McCall et al. 2014, pp. 1380−1392
- MacKay, MacKay & Henderson 2002, p. 200
- Bettelheim et al. 2016, p. 33.
- Schulze-Makuch & Irwin 2008, p. 89.
- Sanderson 1957, p. 229
- Cotton et al. 1999, p. 502
- Russell & Lee 2005, p. 466
- Guntherodt et al. 1976, p. 1513
- Oxtoby, Gillis & Butler 2015, p. I.23
- Vernon 2013, pp. 1703‒1707
- Rochow 1966, pp. 7–8
- Jolly 1966, inside cover
- Bodner & Pardue 1993, p. 354; Cherim 1971, p. 98
- Emsley 2011, passim
- Hermann, Hoffmann & Ashcroft 2013, pp. 11604‒1‒11604‒5
- Corson, MacKenzie & Segrè E 1940, p. 459; Corson, MacKenzie & Segrè E 1940, p. 672
- Moody 1991, p. 303
- Batsanov 1972, pp. 809–813
- Edwards & Sienko 1983, p. 692
- Edwards 1999, p. 416
- Steurer 2007, p. 142; Pyykkö 2012, p. 56
- Edwards & Sienko 1983, p. 695
- Siekierski & Burgess 2002, p. 122
- Restrepo et al. 2006, p. 411
- Thornton & Burdette 2010, p. 86
- Eichler at al. 2008, p. 3262–3266
- Gyanchandani, Mishra, & Sikka 2018, pp. 16–22; Čenčariková & Legut 2018, pp. 576–582
- Mewes et al. 2019, p. 17964
- GSI 2015
- Seaborg 1969, p. 626
- Nash 2005, pp. 3493‒3500
- Scerri 2013, pp. 204–8
- IUPAC Periodic Table of the Elements
- Van Setten et al. 2007, pp. 2460–2461; Oganov et al. 2009, pp. 863–864
- Hill & Holman 2000, p. 124
- Shakhashiri, Dirreen & Williams 1989, pp. 373–374
- Wiberg 2001, pp. 403, 472
- Jesperson, Brady & Hyslop 2012, p. 8; Johnson 1966, pp. 3–4; Cotton & Wilkinson 1976, p. 288
- Lidin 1996, pp. 12, 22, 52, 140, 372, 381, 403: B, C, Ge, As, Se, Sb, Te; Housecroft & Sharpe 2008, p. 472: P, S, I; Rochow 1973, p. 1338: Si
- Oderberg 2007, p. 97
- Bird & Tobin 2018; Vernon 2021, pp. 162–163
- Lidin 1996, pp. 64‒65
- Lavoisier 1789, p. 192
- Kendall 1811, pp. 298–303
- Brande 1821, pp. 5
- Kubaschewski 1949, pp. 931–940
- Remy 1956, p. 9
- White 1962, p. 106
- Johnson 1966, pp. 3−4
- Horvath 1973, pp. 335–336
- Edwards & Sienko 1983, pp. 691–96
- Rao & Ganguly 1986
- Smith & Dwyer 1991, p. 65
- Herman 1999, pp. 701–748
- Hill & Holman 2000, p. 160
- Suresh & Koga 2001, pp. 5940−5944
- Johnson 2007, pp. 15−16
- Edwards 2010, pp. 941–965
- Povh & Rosin 2017, p. 131
- Beach 1911
- Stott 1956, pp. 100–102
- Abbott 1966, p. 18
- Parish 1977, p. 178
- Sanderson 1957, p. 229
- Kneen, Rogers & Simpson 1972, pp. 218–219
- Leach & Ewing 1966, p. 47
- Brady & Senese 2009, p. 52
- Zumdahl & DeCoste 2018, p. 90
- Neuburger 1936; Kitaĭgorodskiĭ 1961, p. 108; Pearson 1972, p. 264; Russell & Lee 2005, pp. 1–8
- Donohue 1982, p. 297
- Okajima & Shomoji 1972, p. 258
- Russell & Lee 2005, pp. 1–8
- Russell & Lee 2005, pp. 1‒8
- Kneen, Rogers & Simpson 1972, pp. 261–264
- Herzfeld 1927, pp. 701–05; Edwards 2000, pp. 100–03
- Aylward & Findlay 2008, p. 134
- Yoder, Suydam & Snavely 1975, p. 58
- Kneen, Rogers & Simpson 1972, pp. 83–84, 225
- Abbott 1966, p. 18
- Kneen, Rogers & Simpson 1972, pp. 263‒264
- Brown et al. 2014, p. 237
- Schweitzer & Pesterfield 2010, passim
- Young et al. 2018, p. 753
- Brown et al. 2014, p. 227
- Siekierski & Burgess 2002, pp. 21, 133, 177
- Moore 2016; Burford, Passmore & Sanders 1989, p. 54
- King & Caldwell 1954, p. 17; Brady & Senese 2009, p. 69
- Nelson 1987, p. 735
- Cao et al. 2021, pp. 20–21
- Emsley 2011, pp. 81, 181; Scott 2016, p. 3
- Kneen, Rogers & Simpson 1972, pp. 226, 360
- Lee 1996, p. 240
- Greenwood & Earnshaw 2002, p. 43
- Cressey 2010
- Siekierski & Burgess 2002, pp. 24–25
- Siekierski & Burgess 2002, p. 23
- Siekierski & Burgess 2002, pp. 52, 101, 111, 124, 194
- Greenwood & Earnshaw 2002, p. 27
- Cox 2004, p. 146
- Luchinskii & Trifonov 1981, pp. 200–220
- Rayner-Canham 2021, p. 212
- Wiberg 2001, passim
- Vernon 2020, p. 222
- Atkins & Overton 2010, pp. 377, 389
- Moody 1991, p. 391
- Rodgers 2010, p. 504; Wulfsberg 2000, p. 726
- Stellman 1998, p. 104-211
- Nakao 1992, p. 426–427
- Hill & Holman 2000, p. 124
- Wiberg 2001, pp. 1761–1762
- Young 2006, p. 1285
- Siebring & Schaff 1980, p. 573
- Goldsmith 1982, p. 526; Hawkes 2001, p. 1686
- Encyclopaedia Britannica 2021
- Royal Society of Chemistry 2021
- Dupasquier 1844, pp. 66–67
- Berzelius 1832, pp. 248–276
- The Chemical News 1864, p. 22
- Williams 2007, pp. 1550–1561
- Wächtershäuser 2014
- Hengeveld R & Fedonkin, pp. 181–226
- Wakeman 1899, p. 562
- Fraps 1913, p. 11
- Parameswaran at al. 2020, p. 210
- Knight 2002
- Fraústo da Silva & Williams 2001, p. 500
- Renouf 1901, pp. 268
- Chambers & Holliday 1982, pp. 273–274; Bohlmann 1992, p. 213; Jentzsch 2015, p. 247
- Vassilakis, Kalemos & Mavridis 2014, p. 1; Hanley & Koga 2018, p. 24; Kaiho 2017, ch. 2, p. 1
- Bailar et al. 1989, p. 742
- Tshitoyan et al. 2019, p. 101
- Hampel & Hawley 1976, p. 174;
- Goodrich 1844, p. 264; The Chemical News 1897, p. 189; Hampel & Hawley 1976, p. 191; Lewis 1993, p. 835; Hérold 2006, pp. 149–50
- Tyler 1948, p. 105; Reilly 2002, pp. 5–6
- Kneen, Rogers & Simpson 1972, pp. 218–221
- Walker & Tarn 1990, p. 510
- Parish 1977, p. 178
- Meyer et al. 2005, p. 284; Manahan 2001, p. 911; Szpunar et al. 2004, p. 17
- Sharp 1981, p. 299
- Roher 2001, pp. 4–6
- Brown & Holme 2006, p. 57
- Oderberg 2007, p. 97
- Jones 2010, pp. 169–71
- Stein 1983, p. 165
- Aylward & Findlay 2008
- Rahm, Hoffmann & Ashcroft 2016, pp. 14625–14632
- Edwards & Sienko 1983
- Hill & Holman 2000, p. 124
- Greenwood & Earnshaw 2002, p. 482
- Moss 1952, p. 192
- Allen & Huheey 1980, pp. 1523–1524
- Wulfsberg 2000, pp. 321, 354
- Wulfsberg 2000, pp. 274–248; no agents producing complexes or insoluble compounds are present other than HOH and OH−; Schweitzer & Pesterfield 2010, pp. 228–229, 232–233
- Edwards & Sienko 1983, p. 693
- Matson & Orbaek 2013, p. 203
- Jolly 1966, p. 20
- Clugston & Flemming 2000, pp. 100–101, 104–105, 302
- Maosheng 2020, p. 962
- Mazej 2020
- Wiberg 2001, p. 1131
- Scerri 2020, p. 375
- Rayner-Canham 2021, p. 92. 139
- Greenwood & Earnshaw 2002, p. 804
- Rudolph 1974, p. 133: "Oxygen and the halogens in particular...are therefore strong oxidizing agents."
- Daniel & Rapp 1976, p. 55
- Cotton et al. 1999, p. 554
- Woodward et al. 1999, pp. 133–194
- Phillips & Williams 1965, pp. 478–479
- Moeller et al. 2012, p. 314
- Lanford 1959, p. 176
- Pilar 1979, p. 646
- Jones & Atkins 2000, p. 15
- Ambrose et al. 1967, p. 545
- Greenwood & Earnshaw 2002, p. 482
- Greenwood & Earnshaw 2002, p. 277
- Greenwood & Earnshaw 2002, p. 482; Berger 1997, p. 86
- Moss 1952, p. 180, 202
- Vernon 2020, p. 218
- Challoner 2014, p. 5; Government of Canada 2015; Gargaud et al. 2006, p. 447
- Crichton 2012, p. 6; Scerri 2013; Los Alamos National Laboratory 2021
- Wulfsberg 2000, pp. 273–274, 620
- Seese & Daub 1985, p. 65
- MacKay, MacKay & Henderson 2002, p. 209
- Cousins, Davidson & García-Vivó 2013, pp. 11809-11811
- Wiberg 2001, pp. 255–257
- Liptrot 1983, p. 161
- Scott & Kanda 1962, p. 153
- Bevan 2015
- Crawford 1968, p. 540
- Benner, Ricardo & Carrigan 2018, pp. 167—168: "The stability of the carbon—carbon bond...has made it the first choice element to scaffold biomolecules. Hydrogen is need for many reasons; at the very least, it terminates C–C chains. Heteroatoms (atoms that are neither carbon nor hydrogen) determine the reactivity of carbon-scaffolded biomolecules. In...life, these are oxygen, nitrogen and, to a lesser extent, sulfur, phosphorus, selenium, and an occasional halogen."
- Zumdahl & Zumdahl 2009, p. 925
- Messler 2009, p. 10
- King et al. 1994, p. 1344; Powell & Tims 1974, pp. 189–191
- Rayner-Canham 2021, p. 216
- Cronyn 2003, pp. 947–951
- Vernon 2020, p. 221
- Rayner-Canham 2021, p. 227
- Rayner-Canham 2011, p. 126
- Vernon 2020, p. 220
- Monteil & Vincent 1976, p. 668–672
- Atkins 2001, pp. 24–25
- Rochow 1977, pp. 1, 4
- MacKay, MacKay & Henderson 2002, p. 436
- Greenwood 2001, p. 2057
- Houghton 1979, p. 59
- Fehlner 1990, p. 205
- Fehlner 1990, pp. 204–05, 207
- Masterton, Hurley & Neth 2011, p. 38
- McCue 1963, p. 264
- Tregarthen 2003, p. 10
- Rochow 1966, passim
- Emsley 2011, pp. 397, 480; Wiberg 2001, p. 780
- Kneen, Rogers & Simpson 1972, pp. 321, 404, 436
- Kneen, Rogers & Simpson 1972, pp. 439
- Kneen, Rogers & Simpson 1972, p. 465
- Kneen, Rogers & Simpson 1972, p. 308
- Wiberg 2001, pp. 505, 681, 781; Glinka 1965, p. 356
- Chung 1987, pp. 4190‒4198; Godfrin & Lauter 1995, pp. 216‒218
- Cambridge Enterprise 2013
- Faraday 1853, p. 42; Holderness & Berry 1979, p. 255
- Partington 1944, p. 405
- Regnault 1853, p. 208
- Wiberg 2001, p. 416
- Bell & Garofalo, p. 131
- Kneen, Rogers & Simpson 1972, pp. 321, 404, 436
- Kneen, Rogers & Simpson 1972, pp. 464
- Kneen, Rogers & Simpson 1972, pp. 308
- Darken & Gurry 1953, pp. 50‒57
- Addison 1964, pp. 70–120; Wulfsberg 1987, pp. 180–188
- Si: Shiell at al. 2021; Ge: Zhao et al. 2017, p. 13909; Te: Brodsky et al. 1972, p. 609–614
- West 1953, pp. 691‒701
- Desai, James & Ho 1984, p. 1160; Matula 1979, p. 1260
- Schaefer 1968, p. 76; Carapella 1968, pp. 29‒32
- Bogoroditskii & Pasynkov 1967, p. 77; Jenkins & Kawamura 1976, p. 88
- Greenwood & Earnshaw 2002, p. 804
- Lide 2003 pp. 6-68–6-95; National Physical Laboratory 1995
- Keeler & Wothers 2013, p. 293
- Wulfsberg 1987, p. 6
- Donohue 1982, passim
- Greenwood & Earnshaw 2002, pp. 479, 482
- Eagleson 1994, p. 820
- Oxtoby, Gillis & Butler 2015, p. 509
- McKetta 1969, p. 2
- Greenwood & Earnshaw 2002, p. 482
- Emsley 2011, p. 13
- Kneen, Rogers & Simpson 1972, p. 264
- Rayner-Canham 2018, p. 203
- Rochow 1966, p. 4
- Welcher 2001, p. 3–32
- Mackin 2014, p. 80
- Johnson 1966, pp. 105–108
- Stein 1969, pp. 5396‒5397; Pitzer 1975, pp. 760‒761
- Hoffman, Lee & Pershina 2006
- Tantardini & Oganov 2021, p. 2
- Wiberg 2001, passim
- Ellis 2006, pp. 3167‒3186
- Pitts, Holl & Lectka 2018, p. 1924
- Wulfsberg 1987, pp. 202‒206
- Braunstein & Danopoulos 2021, pp. 7346‒7397
- Hill 2010, p. 210
- Riley et al. 2020, p. 7711
- Wiberg 2001, pp. 419‒422
- Zoroddu et al. 2019, pp. 120–129
- Science Learning Hub–Pokapū Akoranga Pūtaiao 2021
- Labinger 2019, p. 5
- Baird & Cann 2012, p. 519
- Prinessa 2015, p. 22
- Farooq & Dietz 2015, p. 7
- Cockell 2019, pp. 212; see also pp. 210–211 on Se
- Emsley 2011, pp. 376, 391, 476
- Hashemian & Fallahian 2014, pp. 138–142
- Winkler et al. 2016, pp. 44–64
- Goldstein 1975, pp. 757–759
- Yamaguchi & Shirai 1996, pp. 3–27 (3)
- Vernon 2020, p. 223
- Vernon 2020, p. 220
- Woodward et al. 1999, p. 134
- Dalton 2019
- Wells 1984, p. 534
- Rao 2002, p. 22
- Porterfield 1993, p. 336
- Puddephatt & Monaghan 1989, p. 59
- Sidorov 1960, pp. 599‒603
- Atkins 2006 et al., pp. 8, 122–123
- Wiberg 2001, p. 750
- McMillan 2006, p. 823
- Sanderson 1967, p. 172
- Mingos 2019, p. 27
- House 2008, p. 441
- King 1995, p. 182
- Ritter 2011, p. 10
- Wiberg 2001, p. 399
- Kläning & Appelman 1988, p. 3760
- Jones 1973, pp. 378–379
- Lidin 1996, pp. 22, 12
- Rochow 1973, p. 1338: "Hot concentrated …nitric acid can oxidize finely-divided silicon so rapidly as to bring the mass to incandescence."; Lidin 1996, pp. 140, 372, 403: Ge, Sb, Te
- Lidin 1996, p. 52: C
- Housecroft & Sharpe 2008, p. 472
- Housecroft & Sharpe 2008, p. 472; Lidin 1996, p. 381
- Ruff & Kwasnik 1935
- Wickleder, Pley & Büchner 2006; Betke & Wickleder 2011
- Cotton 1994, p. 3606
- Keogh 2005, p. 16
- Raub & Griffith 1980, p. 167
- Kneen, Rogers & Simpson 1972, p. 366
- Kneen, Rogers & Simpson 1972, p. 381
- Lidin 1996, p. 140; Wiberg 2001, p. 764
- Greenwood & Earnshaw 2002, p. 552
- Wickleder 2007, p. 350
- Holliday, Hughes & Walker 1973, p. 1195; Lidin 1996, p. 361
- Eagleson 1994, p. 821
- Greenwood & Earnshaw 2002, p. 786
- Furuseth et al. 1974
- Steudel 1977, p. 176
- Barton 2021, p. 200
- Shanabrook, Lannin & Hisatsune 1981, pp. 130‒133
- Borg & Dienes 1992, p. 26
- Wiberg 2001, p. 796
- Cacace, de Petris & Troiani 2002, pp. 480‒481
- Koziel 2002, p. 18
- Gusmão, Sofer & Pumera 2017, p. 8052–8053; Berger 1997, p. 84; Vernon 2013, pp. 1704‒1705
- Piro et al. 2006, pp. 1276‒1279
- Steudel & Eckert 2003, p. 1
- Greenwood & Earnshaw 2002, pp. 659–660
- Moss 1952, p. 192; Greenwood & Earnshaw 2002, p. 751
- Mikla & Mikla 2012, p. 63; Yost & Russell 1946, p. 282
- Shiell at al. 2021
- Zhao et al. 2017, p. 13909
- Brodsky et al. 1972, p. 609–614
- Yousuf 1998, p. 425; Elatresh & Bonev 2020
- Errandonea 2020, p. 595
- Su et al. 2020, pp. 1621–1649
- Cox 1997, pp. 17, 19
- Ostriker & Steinhardt 2001, pp. 46‒53
- Nelson 1987, p. 732
- Cox 1997, passim
- Cox 2000, pp. 258–259; Möller 2003, p. 173; Trenberth & Smith 2005, p. 864
- Emsley 2011, p. 220
- Emsley 2011, p. 440
- Zhu et al. 2014, pp. 644–648
- Schmedt, Mangstl & Kraus 2012, p. 7847‒7849
- Emsley 2011, p. 117
- National Center for Biotechnology Information 2021
- Greenwood & Earnshaw 2002, p. 270–271
- Boyd 2011, p. 570
- Cox 1997, pp. 130–132; Emsley 2011, passim
- Hurlbut 1961, p. 132
- Stewart n.d.
- Boise State University
- National Institute of Standards and Technology 2013
- Reinhardt at al. 2015; Eagleson 1994, p. 1053: SF6
- Windmeier & Barron 2013
- Kiiski et al. 2016
- Beard et al. 2021
- Slye 2008
- Emsley 2011, pp. 39, 44, 80–81, 85, 199, 248, 263, 367, 478, 531, 610
- Maroni 1995, pp. 108‒123
- Smulders 2011, pp. 416—421
- Chen 1990, part 17.2.1
- Hall 2021, p. 143
- Csele 2016 ; Winstel 2000
- Davis et al. 2006, p. 431–432
- Grondzik et al. 2010, p. 561
- Imbertierti 2020
- Oxford English Dictionary; Eagleson 1994 (all bar germanic acid); Wiberg 2001, p. 897: germanic acid
- Bhuwalka et al. 2021, pp. 10097–10107
- Brandt & Weiler 2000
- King 2019, p. 408
- Gaffney & Marley 2017, p. 27
- Harbison, Bourgeois & Johnson 2015, p. 364
- Bolin 2017, p. 2-1
- Labinger 2019, pp. 303–328 (305)
- Weeks 1935, p. 161
- Emsley 2011, p. 51
- Rees 1819: "Tellurium"
- Encyclopaedia Britannica 1810, vol 14, p. 249
- Weeks 1935, pp. 158–159
- Abbott D 1966, An Introduction to the Periodic Table, J. M. Dent & Sons, London
- Addison WE 1964, The Allotropy of the Elements, Oldbourne, London
- Allen LC & Huheey JE 1980, "The definition of electronegativity and the chemistry of the noble gases", Journal of Inorganic and Nuclear Chemistry, vol. 42, no. 10, doi: 10.1016/0022-1902(80)80132-1
- Ambrose M et al. 1967, General Chemistry, Harcourt, Brace & World, New York
- Atkins PA 2001, The Periodic Kingdom: A Journey Into the Land of the Chemical Elements, Phoenix, London, ISBN 978-1-85799-449-0
- Atkins et al. 2006, Shriver & Atkins' Inorganic Chemistry, 4th ed., Oxford University Press, Oxford, ISBN 978-0-7167-4878-6
- Atkins P & Overton T 2010, Shriver & Atkins' Inorganic Chemistry, 5th ed., Oxford University Press, Oxford, ISBN 978-0-19-923617-6
- Aylward G & Findlay T 2008, SI Chemical Data, John Wiley & Sons, Australia: Brisbane, ISBN 978-0-470-81638-7
- Bailar et al. 1989, Chemistry, 3rd ed., Harcourt Brace Jovanovich, San Diego, ISBN 978-0-15-506456-0
- Baird C & Cann M 2012, Environmental Chemistry, 5th ed., WH Freeman and Company, New York, ISBN 978-1-4292-7704-4
- Barton AFM 2021, States of Matter, States of Mind, CRC Press, Boca Raton, ISBN 978-0-7503-0418-4
- Beach FC (ed.) 1911, The Americana: A universal reference library, vol. XIII, Mel–New, Metalloid, Scientific American Compiling Department, New York
- Beard A, Battenberg, C & Sutker BJ 2021, "Flame retardants", in Ullmann's Encyclopedia of Industrial Chemistry, doi:10.1002/14356007.a11_123.pub2
- Bell RL & Garofalo J 2005, Science Units for Grades 9–12, International Society for Technology in Education, ISBN 978-1-56484-217-6
- Benner SA, Ricardo A & Carrigan MA 2018, "Is there a common chemical model for life in the universe?", in Cleland CE & Bedau MA (eds), The Nature of Life: Classical and Contemporary Perspectives from Philosophy and Science, Cambridge University Press, Cambridge, ISBN 978-1-108-72206-3
- Berger LI 1997, Semiconductor Materials, CRC Press, Boca Raton, ISBN 978-0-8493-8912-2
- Berzelius JJ & Bache AD 1832, "An essay on chemical nomenclature, prefixed to the treatise on chemistry", The American Journal of Science and Arts, vol.22
- Betke U & Wickleder MS 2011, "Sulfates of the refractory metals: Crystal structure and thermal behavior of Nb2O2(SO4)3, MoO2(SO4), WO(SO4)2, and two modifications of Re2O5(SO4)2", Inorganic chemistry, vol. 50, no. 3, pp. 858–872, doi:10.1021/ic101455z
- Bettelheim et al. 2016, Introduction to General, Organic, and Biochemistry, 11th ed., Cengage Learning, Boston, ISBN 978-1-285-86975-9
- Bevan D 2015, Cambridge International AS and A Level Chemistry Revision Guide, 2nd ed., Hodder Education, London, ISBN 978-1-4718-2942-0
- Bhuwalka et al. 2021, "Characterizing the changes in material use due to vehicle electrification", Environmental Science & Technology vol. 55, no. 14, doi:10.1021/acs.est.1c00970
- Bird A & Tobin E 2018, "Natural kinds", in The Stanford Encyclopedia of Philosophy, accessed July 10, 2021
- Bodner GM & Pardue HL 1993, Chemistry, An Experimental Science, John Wiley & Sons, New York, ISBN 0-471-59386-9
- Bogoroditskii NP & Pasynkov VV 1967, Radio and Electronic Materials, Iliffe Books, London
- Bohlmann R 1992, "Synthesis of halides", in Winterfeldt E (ed.), Heteroatom manipulation, Pergamon Press, Oxford, ISBN 978-0-08-091249-3
- Boise State University 2020, "Cost-effective manufacturing methods breathe new life into black phosphorus research", accessed July 9, 2021
- Bolin P 2017, "Gas-insulated substations", in McDonald JD (ed.), Electric Power Substations Engineering, 3rd, ed., CRC Press, Boca Raton, FL, ISBN 978-1-4398-5638-3
- Borg RG & Dienes GJ 1992, The Physical Chemistry of Solids, Academic Press, Boston, ISBN 978-0-12-118420-9
- Boyd R 2011, "Selenium stories", Nature Chemistry, vol. 3, doi:10.1038/nchem.1076
- Brady JE & Senese F 2009, Chemistry: The study of Matter and its Changes, 5th ed., John Wiley & Sons, New York, ISBN 978-0-470-57642-7
- Brande WT 1821, A Manual of Chemistry, vol. II, John Murray, London
- Brandt HG & Weiler H, 2000, "Welding and cutting", in Ullmann's Encyclopedia of Industrial Chemistry, doi:10.1002/14356007.a28_203
- Braunstein P & Danopoulos AA 2021, "Transition metal chain complexes supported by soft donor assembling ligands", Chemical Reviews, vol. 121, no. 13, doi:10.1021/acs.chemrev.0c01197
- Brodsky MH, Gambino RJ, Smith JE Jr & Yacoby Y 1972, "The Raman spectrum of amorphous tellurium", Physica Status Solidi (b), vol. 52, doi:10.1002/pssb.2220520229
- Brown et al. 2014, Chemistry: The Central Science, 3rd ed., Pearson Australia: Sydney, ISBN 978-1-4425-5460-3
- Brown L & Holme T 2006, Chemistry for Engineering Students, Thomson Brooks/Cole, Belmont California, ISBN 978-0-495-01718-9
- Burford N, Passmore J & Sanders JCP 1989, "The preparation, structure, and energetics of homopolyatomic cations of groups 16 (the chalcogens) and 17 (the halogens), in Liebman JF & Greenberg A, From atoms to polymers : isoelectronic analogies, VCH: New York, ISBN 978-0-89573-711-3
- Cacace F, de Petris G & Troiani A 2002, "Experimental detection of tetranitrogen", Science, vol. 295, no. 5554, doi:10.1126/science.1067681
- Cambridge Enterprise 2013, "Carbon 'candy floss' could help prevent energy blackouts", Cambridge University, accessed August 28, 2013
- Cao et al. 2021, "Understanding periodic and non-periodic chemistry in periodic tables", Frontiers in Chemistry, vol. 8, article 813, doi:10.3389/fchem.2020.00813
- Carapella SC 1968, "Arsenic" in Hampel CA (ed.), The Encyclopedia of the Chemical Elements, Reinhold, New York
- Čenčariková H & Legut D 2018, "The effect of relativity on stability of copernicium phases, their electronic structure and mechanical properties", Physica B, vol. 536, doi:10.1016/j.physb.2017.11.035
- Csele M 2016, Lasers, in Ullmann's Encyclopedia of Industrial Chemistry, doi:10.1002/14356007.a15_165.pub2
- Challoner J 2014, The Elements: The New Guide to the Building Blocks of our Universe, Carlton Publishing Group, ISBN 978-0-233-00436-5
- Chambers C & Holliday AK 1982, Inorganic Chemistry, Butterworth & Co., London, ISBN 978-0-408-10822-5
- Chen K 1990, Industrial Power Distribution and Illuminating Systems, Marcel Dekker, New York, ISBN 978-0-8247-8237-5
- Cherim SM 1971, Chemistry for Laboratory Technicians, Saunders, Philadelphia, ISBN 978-0-7216-2515-7
- Chung DD 1987, "Review of exfoliated graphite", Journal of Materials Science, vol. 22, doi:10.1007/BF01132008
- Clugston MJ & Flemming R 2000, Advanced Chemistry, Oxford University Press, Oxford, ISBN 978-0-19-914633-8
- Cockell C 2019, The Equations of Life: How Physics Shapes Evolution, Atlantic Books: London, ISBN 978-1-78649-304-0
- Cotton SA 1994, "Scandium, yttrium & the lanthanides: Inorganic & coordination chemistry", in RB King (ed.), Encyclopedia of Inorganic Chemistry, 2nd ed., vol. 7, John Wiley & Sons, New York, pp. 3595–3616, ISBN 978-0-470-86078-6
- Cotton et al. 1999, Advanced Inorganic Chemistry, 6th ed., Wiley, New York, ISBN 978-0-471-19957-1
- Cotton FA & Wilkinson G 1976, Basic inorganic chemistry, Wiley, New York, ISBN 978-0-471-17557-5
- Cousins DM, Davidson MG & García-Vivó D 2013, "Unprecedented participation of a four-coordinate hydrogen atom in the cubane core of lithium and sodium phenolates", Chemical Communications, vol. 49, doi:10.1039/C3CC47393G
- Cox AN (ed) 2000, Allen's Astrophysical Quantities, 4th ed., AIP Press, New York, ISBN 978-0-387-98746-0
- Cox PA 1997, The Elements: Their Origins, Abundance, and Distribution, Oxford University Press, Oxford, Oxford, ISBN 978-0-19-855298-7
- Cox T 2004, Inorganic Chemistry, 2nd ed., BIOS Scientific Publishers, London, ISBN 978-1-85996-289-3
- Crawford FH 1968, Introduction to the Science of Physics, Harcourt, Brace & World, New York
- Crichton R 2012, Biological Inorganic Chemistry: A New Introduction to Molecular Structure and Function, 2nd ed., Elsevier, Amsterdam, ISBN 978-0-444-53783-6
- Cressey 2010, "Chemists re-define hydrogen bond", Nature newsblog, accessed August 23, 2017
- Cronyn MW 2003, "The proper place for hydrogen in the periodic table", Journal of Chemical Education, vol. 80, no. 8, doi:10.1021/ed080p947
- Dalton L 2019, "Argon reacts with nickel under pressure-cooker conditions", Chemical & Engineering News, accessed November 6, 2019
- Daniel PL & Rapp RA 1976, "Halogen corrosion of metals", in Fontana MG & Staehle RW (eds), Advances in Corrosion Science and Technology, Springer, Boston, doi:10.1007/978-1-4615-9062-0_2
- Darken L & Gurry R 1953, Physical chemistry of Metals, McGraw-Hill, New York
- Davis et al. 2006, "Atomic iodine lasers", in Endo M & Walter RF (eds) 2006, Gas Lasers, CRC Press, Boca Raton, Florida, ISBN 978-0-470-19565-9
- Deming HG 1923, General chemistry: An elementary survey, John Wiley & Sons, New York
- Desai PD, James HM & Ho CY 1984, "Electrical Resistivity of Aluminum and Manganese", Journal of Physical and Chemical Reference Data, vol. 13, no. 4, doi:10.1063/1.555725
- Donohue J 1982, The Structures of the Elements, Robert E. Krieger, Malabar, Florida, ISBN 978-0-89874-230-5
- Dupasquier A 1844, Traité élémentaire de chimie industrielle, Charles Savy Juene, Lyon.
- Eagleson M 1994, Concise Encyclopedia Chemistry, Walter de Gruyter, Berlin, ISBN 978-3-11-011451-5
- Edwards PP 1999, "Chemically engineering the metallic, insulating and superconducting state of matter", in Seddon KR & Zaworotko M (eds), Crystal Engineering: The Design and Application of Functional Solids, Kluwer Academic, Dordrecht, ISBN 978-0-7923-5905-0
- Edwards PP 2000, "What, why and when is a metal?", in Hall N (ed.), The New Chemistry, Cambridge University, Cambridge, ISBN 978-0-521-45224-3
- Edwards PP et al. 2010, "…a metal conducts and a non-metal doesn’t", Philosophical Transactions of the Royal Society A, 2010, vol, 368, no. 1914, doi:10.1098/rsta.2009.0282
- Edwards PP & Sienko MJ 1983, "On the occurrence of metallic character in the Periodic Table of the Elements", Journal of Chemical Education, vol. 60, no. 9, doi:10.1021ed060p691, PMID 25666074
- Eichler et al. 2008, "Thermochemical and physical properties of element 112", Angewandte Chemie, vol. 47, no. 17, doi:10.1002/anie.200705019
- Elatresh SF & Bonev SA 2020, "Stability and metallization of solid oxygen at high pressure", Physical Chemistry Chemical Physics, vol. 22, no. 22, doi:10.1039/C9CP05267D
- Ellis JE 2006, "Adventures with substances containing metals in negative oxidation states", Inorganic Chemistry, vol. 45, no. 8, doi:10.1021/ic052110i, PMID 16602773
- Emsley J 2011, Nature's Building Blocks: An A–Z Guide to the Elements, Oxford University Press, Oxford, ISBN 978-0-19-850341-5
- Encyclopaedia Britannica 2021, Periodic table, accessed September 21
- Encyclopaedia Britannica, Or a Dictionary of Arts, Sciences, and Miscellaneous Literature 1810, Archibald Constable, Edinburgh
- Errandonea D 2020, "Pressure-induced phase transformations," Crystals, vol. 10, doi:10.3390/cryst10070595
- Faraday M 1853, The Subject Matter of a Course of Six Lectures on the Non-metallic Elements, (arranged by John Scoffern), Longman, Brown, Green, and Longmans, London
- Farooq MA & Dietz K-J 2015, "Silicon as versatile player in plant and human biology: Overlooked and poorly understood", Frontiers of Plant Science, vol. 6, article 994, doi:10.3389/fpls.2015.00994
- Fehlner TP 1990, "The metallic Face of Boron", in AG Sykes (ed.), Advances in Inorganic Chemistry, vol. 35, Academic Press, Orlando, pp. 199–233
- Fraps GS 1913, Principles of Agricultural Chemistry, The Chemical Publishing Company, Easton, PA
- Fraústo da Silva JJR & Williams RJP 2001, The Biological Chemistry of the Elements: The Inorganic Chemistry of Life, 2nd ed., Oxford University Press, Oxford, ISBN 978-0-19-850848-9
- Furuseth S, Selte K, Hope H, Kjekshus A & Klewe B 1974, "Iodine oxides. Part V. The crystal structure of (IO)2SO4", Acta Chemica Scandinavica A, vol. 28, pp. 71–76, doi:10.3891/acta.chem.scand.28a-0071
- Gaffney J & Marley N 2017, General Chemistry for Engineers, Elsevier, Amsterdam, ISBN 978-0-12-810444-6
- Gargaud et al. (eds) 2006, Lectures in Astrobiology, vol. 1, part 1: The Early Earth and Other Cosmic Habitats for Life, Springer, Berlin, ISBN 978-3-540-29005-6
- Glinka N 1965, General Chemistry, trans. D Sobolev, Gordon & Breach, New York
- Godfrin H & Lauter HJ 1995, "Experimental properties of 3He adsorbed on graphite", in Halperin WP (ed.), Progress in Low Temperature Physics, volume 14, Elsevier Science B.V., Amsterdam, ISBN 978-0-08-053993-5
- Goldsmith RH 1982, 'Metalloids', Journal of Chemical Education, vol. 59, no. 6, pp. 526–27, doi:10.1021/ed059p526
- Goldstein N 1975, "Radon seed implants: Residual radioactivity after 33 Years", Archives of Dermatology, vol. 111, no. 6, doi:10.1001/archderm.1975.01630180085013
- Goodrich BG 1844, A Glance at the Physical Sciences, Bradbury, Soden & Co., Boston
- Government of Canada 2015, Periodic table of the elements, accessed August 30, 2015
- Greenwood NN 2001, "Main group element chemistry at the Millennium", Journal of the Chemical Society, Dalton Transactions, issue 14, pp. 2055–66, doi:10.1039/b103917m
- Greenwood NN & Earnshaw A 2002, Chemistry of the Elements, 2nd ed., Butterworth-Heinemann, ISBN 978-0-7506-3365-9
- Grondzik WT et al. 2010, Mechanical and Electrical Equipment for Buildings, 11th ed., John Wiley & Sons, Hoboken, ISBN 978-0-470-19565-9
- GSI 2015, Research Program – Highlights, 14 Dec, accessed November 9, 2016
- Gusmão R, Sofer, Z & Pumera M 2017, "Black phosphorus rediscovered: From bulk material to monolayers", Angewandte Chemie International Edition, vol. 56, no. 28, doi:10.1002/anie.201610512
- Gyanchandani J, Mishra V & Sikka SK 2018, "Super heavy element copernicium: Cohesive and electronic properties revisited", Solid State Communications, vol. 269, doi:10.1016/j.ssc.2017.10.009
- Hall RA 2021, Pop Goes the Decade: The 2000s, ABC-CLIO, Santa Barbara, California, ISBN 978-1-4408-6812-2
- Hampel CA & Hawley GG 1976, Glossary of Chemical Terms, Van Nostrand Reinhold, New York, ISBN 978-0-442-23238-2
- Hanley JJ & Koga KT 2018, "Halogens in terrestrial and cosmic geochemical systems: Abundances, geochemical behaviours, and analytical methods" in The Role of Halogens in Terrestrial and Extraterrestrial Geochemical Processes: Surface, Crust, and Mantle, Harlov DE & Aranovich L (eds), Springer, Cham, ISBN 978-3-319-61667-4
- Harbison RD, Bourgeois MM & Johnson GT 2015, Hamilton and Hardy's Industrial Toxicology, 6th ed., John Wiley & Sons, Hoboken, ISBN 978-0-470-92973-5
- Hashemian SM & Fallahian F 2014, "The use of heliox in critical care", International Journal of Critical Illness and Injury Science, vol. 4, no. 2, doi:10.4103/2229-5151.134153
- Hawkes SJ 2001, 'Semimetallicity', Journal of Chemical Education, vol. 78, no. 12, pp. 1686–87, doi:10.1021/ed078p1686
- Hengeveld R & Fedonkin MA 2007, "Bootstrapping the energy flow in the beginning of life", Acta Biotheoretica, vol. 55, doi:10.1007/s10441-007-9019-4
- Herman ZS 1999, "The nature of the chemical bond in metals, alloys, and intermetallic compounds, according to Linus Pauling", in Maksić, ZB, Orville-Thomas WJ (eds), 1999, Pauling's Legacy: Modern Modelling of the Chemical Bond, Elsevier, Amsterdam, doi:10.1016/S1380-7323(99)80030-2
- Hermann A, Hoffmann R & Ashcroft NW 2013, "Condensed Astatine: Monatomic and metallic", Physical Review Letters, vol. 111, doi:10.1103/PhysRevLett.111.116404
- Hérold A 2006, "An arrangement of the chemical elements in several classes inside the periodic table according to their common properties", Comptes Rendus Chimie, vol. 9, no. 1, doi:10.1016/j.crci.2005.10.002
- Herzfeld K 1927, "On atomic properties which make an element a metal", Physical Review, vol. 29, no. 5, doi:10.1103PhysRev.29.701
- Hill MS 2010, "Homocatenation of metal and metalloid main group elements", in Parkin G (ed.), Metal-Metal Bonding. Structure and Bonding, vol 136. Springer, Berlin, doi:10.1007/978-3-642-05243-9_6
- Hill G & Holman J 2000, Chemistry in Context, 5th ed., Nelson Thornes, Cheltenham, ISBN 978-0-17-448307-6
- Hoffman DC, Lee DM & Pershina V 2006, "Transactinides and the future elements", in Morss E, Norman M & Fuger J (eds), The Chemistry of the Actinide and Transactinide Elements, 3rd ed., Springer Science+Business Media, Dordrecht, The Netherlands, ISBN 978-1-4020-3555-5
- Holderness A & Berry M 1979, Advanced Level Inorganic Chemistry, 3rd ed., Heinemann Educational Books, London, ISBN 978-0-435-65435-1
- Holliday AK, Hughes G & Walker SM 1973, "Carbon", in Bailar et al. (eds.), Comprehensive Inorganic Chemistry, vol. 1, Pergamon Press, Oxford, ISBN 978-0-08-015655-2
- Horvath AL 1973, "Critical temperature of elements and the periodic system", Journal of Chemical Education, vol. 50, no. 5, doi:10.1021/ed050p335
- Houghton RP 1979, Metal Complexes in Organic Chemistry, Cambridge University Press, Cambridge, ISBN 978-0-521-21992-1
- House JE 2008, Inorganic Chemistry, Elsevier, Amsterdam, ISBN 978-0-12-356786-4
- Housecroft CE & Sharpe AG 2008, Inorganic Chemistry, 3rd ed., Prentice-Hall, Harlow, ISBN 978-0-13-175553-6
- Hurlbut Jr CS 1961, Manual of Mineralogy, 15th ed., John Wiley & Sons, New York
- Iler RK 1979, The Chemistry of Silica: Solubility, Polymerization, Colloid and Surface properties, and Biochemistry, John Wiley, New York, ISBN 978-0-471-02404-0
- Imberti C & Sadler PJ, 2020, "150 years of the periodic table: New medicines and diagnostic agents", in Sadler PJ & van Eldik R 2020, Advances in Inorganic Chemistry, vol. 75, Academic Press, ISBN 978-0-12-819196-5
- IUPAC Periodic Table of the Elements, accessed October 11th, 2021
- Jenkins GM & Kawamura K 1976, Polymeric Carbons—Carbon Fibre, Glass and Char, Cambridge University Press, Cambridge, ISBN 978-0-521-20693-8
- Jentzsch AV & Matile S 2015, "Anion transport with halogen bonds", in Metrangolo P & Resnati G (eds), Halogen Bonding I: Impact on Materials Chemistry and Life Sciences, Springer, Cham, ISBN 978-3-319-14057-5
- Jesperson ND, Brady JE, Hyslop A 2012, Chemistry: The Molecular Nature of Matter, 6th ed., John Wiley & Sons, Hoboken NY, ISBN 978-0-470-57771-4
- Johnson D (ed.) 2007, Metals and Chemical Change, RSC Publishing, Cambridge, ISBN 978-0-85404-665-2
- Johnson RC 1966, Introductory Descriptive Chemistry, WA Benjamin, New York
- Jolly WL 1966, The Chemistry of the Non-metals, Prentice-Hall, Englewood Cliffs, New Jersey
- Jones BW 2010, Pluto: Sentinel of the Outer Solar System, Cambridge University, Cambridge, ISBN 978-0-521-19436-5
- Jones K 1973, "Nitrogen", in Bailar et al. (eds.), Comprehensive Inorganic Chemistry, vol. 2, Pergamon Press, Oxford, ISBN 978-0-08-016988-0
- Jones L & Atkins P 2000, Chemistry: Molecules, Matter, and Change, 4th ed., WH Freeman and Company, New York, ISBN 978-0-7167-3254-9
- Kaiho T 2017, Iodine Made Simple, CRC Press, e-book, doi:10.1201/9781315158310
- Keeler J & Wothers P 2013, Chemical Structure and Reactivity: An Integrated Approach, Oxford University Press, Oxford, ISBN 978-0-19-960413-5
- Kendall EA 1811, Pocket encyclopædia, 2nd ed., vol. III, Longman, Hurst, Rees, Orme, and Co., London
- Kent JA 2007, Kent and Riegel's Handbook of Industrial Chemistry and Biotechnology, 11th ed, vol. 1, Springer, New York, ISBN 978-0-387-27842-1
- Keogh DW 2005, 'Actinides: Inorganic & coordination chemistry', in RB King (ed.), Encyclopedia of Inorganic Chemistry, 2nd ed., vol. 1, John Wiley & Sons, New York, pp. 2–32, ISBN 978-0-470-86078-6
- Kiiski et al. 2016, "Fertilizers, 1. General", in Ullmann's Encyclopedia of Industrial Chemistry, doi:10.1002/14356007.a10_323.pub4
- King AH 2019, "Our elemental footprint", Nature Materials, vol. 18, doi:10.1038/s41563-019-0334-3
- King RB 1994, Encyclopedia of Inorganic Chemistry, vol. 3, John Wiley & Sons, New York, ISBN 978-0-471-93620-6
- King RB 1995, Inorganic Chemistry of Main Group Elements, VCH, New York, ISBN 978-1-56081-679-9
- King GB & Caldwell WE 1954, The Fundamentals of College Chemistry, American Book Company, New York
- Kitaĭgorodskiĭ AI 1961, Organic Chemical Crystallography, Consultants Bureau, New York
- Kläning UK & Appelman EH 1988, "Protolytic properties of perxenic acid", Inorganic Chemistry, vol. 27, no. 21, doi:10.1021/ic00294a018
- Kneen WR, Rogers MJW & Simpson P 1972, Chemistry: Facts, Patterns, and Principles, Addison-Wesley, London, ISBN 978-0-201-03779-1
- Knight J 2002, Science of Everyday Things: Real-life chemistry, Gale Group, Detroit, ISBN 9780787656324
- Koziel JA 2002, "Sampling and sample preparation for indoor air analysis", in Pawliszyn J (ed.), Comprehensive Analytical Chemistry, vol. 37, Elsevier Science B.V., Amsterdam, ISBN 978-0-444-50510-1
- Kubaschewski O 1949, "The change of entropy, volume and binding state of the elements on melting", Transactions of the Faraday Society, vol. 45, doi:10.1039/TF9494500931
- Labinger JA 2019, "The history (and pre-history) of the discovery and chemistry of the noble gases", in Giunta CJ, Mainz VV & Girolami GS (eds), 150 Years of the Periodic Table: A Commemorative Symposium, Springer Nature, Cham, Switzerland, ISBN 978-3-030-67910-1
- Lanford OE 1959, Using Chemistry, McGraw-Hill, New York
- Lavoisier A 1789, Traité Élémentaire de Chimie, présenté dans un ordre nouveau, et d'après des découvertes modernes, Cuchet, Paris
- Leach RB & Ewing GW 1966, Chemistry, Doubleday, New York
- Lee JD 1996, Concise Inorganic Chemistry, 5th ed., Blackwell Science, Oxford, ISBN 978-0-632-05293-6
- Lewis RJ 1993, Hawley's Condensed Chemical Dictionary, 12th ed., Van Nostrand Reinhold, New York, ISBN 978-0-442-01131-4
- Lide DR (ed.) 2003, CRC Handbook of Chemistry and Physics, 84th ed., CRC Press, Boca Raton, Florida, Section 6, Fluid Properties; Vapor Pressure
- Lidin RA 1996, Inorganic Substances Handbook, Begell House, New York, ISBN 978-0-8493-0485-9
- Liptrot GF 1983, Modern Inorganic Chemistry, 4th Ed., Bell & Hyman, ISBN 978-0-7135-1357-8
- Los Alamos National Laboratory 2021, Periodic Table of Elements: A Resource for Elementary, Middle School, and High School Students, accessed September 19, 2021
- Luchinskii GP & Trifonov DN 1981, "Some problems of chemical elements classification and the structure of the periodic system", in Uchenie o Periodichnosti. Istoriya i Sovremennoct, (Russian) Nauka, Moscow
- MacKay KM, MacKay RA & Henderson W 2002, Introduction to Modern Inorganic Chemistry, 6th ed., Nelson Thornes, Cheltenham, ISBN 978-0-7487-6420-4
- Mackin M 2014, Study Guide to Accompany Basics for Chemistry, Elsevier Science, Saint Louis, ISBN 978-0-323-14652-4
- Manahan SE 2001, Fundamentals of Environmental Chemistry, 2nd ed., CRC Press, Boca Raton, Florida, ISBN 978-1-56670-491-5
- Maosheng M 2020, "Noble gases in solid compounds show a rich display of chemistry with enough pressure", Frontiers in Chemistry, vol. 8, doi:10.3389/fchem.2020.570492
- Maroni M, Seifert B & Lindvall T (eds) 1995, "Physical pollutants", in Indoor Air Quality: A Comprehensive Reference Book, Elsevier, Amsterdam, ISBN 978-0-444-81642-9
- Masterton W, Hurley C & Neth E 2011, Chemistry: Principles and Reactions, 7th ed., Brooks/Cole, Belmont, California, ISBN 978-1-111-42710-8
- Matson M & Orbaek AW 2013, Inorganic Chemistry for Dummies, John Wiley & Sons: Hoboken, ISBN 978-1-118-21794-8
- Matula RA 1979, "Electrical resistivity of copper, gold, palladium, and silver", Journal of Physical and Chemical Reference Data, vol. 8, no. 4, doi:10.1063/1.555614
- Mazej Z 2020, "Noble-gas chemistry more than half a century after the first report of the noble-gas compound", Molecules, vol. 25, no. 13, doi:10.3390/molecules25133014, PMID 32630333, PMC 7412050
- McCall et al., 2014, Bromine is an essential trace element for assembly of collagen IV scaffolds in tissue development and architecture, Cell, vol. 157, no. 6, doi:10.1016/j.cell.2014.05.009, PMID 24906154, PMC 4144415
- McCue JJ 1963, World of Atoms: An Introduction to Physical Science, Ronald Press, New York
- McKetta Jr JJ (ed.), Encyclopedia of Chemical Processing and Design, Volume 36 – Phosphorus to Pipeline Failure: Subsidence Strains, CRC Press, Boca Raton, ISBN 978-0-8247-2486-3
- McMillan P 2006, "A glass of carbon dioxide", Nature, vol. 441, doi:10.1038/441823a
- Messler Jr RW 2011, The Essence of Materials for Engineers, Jones and Bartlett Learning, Sudbury, Massachusetts, ISBN 978-0-7637-7833-0
- Mewes et al. 2019, "Copernicium is a relativistic noble liquid", Angewandte Chemie International Edition, vol. 58, doi:10.1002/anie.201906966
- Meyer et al. (eds) 2005, Toxicity of Dietborne Metals to Aquatic Organisms, Proceedings from the Pellston Workshop on Toxicity of Dietborne Metals to Aquatic Organisms, 27 July–1 August 2002, Fairmont Hot Springs, British Columbia, Canada, Society of Environmental Toxicology and Chemistry, Pensacola, Florida, ISBN 978-1-880611-70-8
- Mikla VI & Mikla VV 2012, Amorphous Chalcogenides: The Past, Present and Future, Elsevier, Boston, ISBN 978-0-12-388429-9
- Mingos DMP 2019, "The discovery of the elements in the Periodic Table", in Mingos DMP (ed.), The Periodic Table I. Structure and Bonding, Springer Nature, Cham, doi:10.1007/978-3-030-40025-5
- Moeller T et al. 2012, Chemistry: With Inorganic Qualitative Analysis, Academic Press, New York, ISBN 978-0-12-503350-3
- Möller D 2003, Luft: Chemie, Physik, Biologie, Reinhaltung, Recht, Walter de Gruyter, Berlin, ISBN 978-3-11-016431-2
- Monteil Y & Vincent H 1976, "Phosphorus compounds with the VI B group elements", Zeitschrift für Naturforschung B, doi:10.1515/znb-1976-0520
- Moody B 1991, Comparative Inorganic Chemistry, 3rd ed., Edward Arnold, London, ISBN 978-0-7131-3679-1
- Moore JT 2016, Chemistry for Dummies, 2nd ed., ch. 16, Tracking periodic trends, John Wiley & Sons: Hoboken, ISBN 978-1-119-29728-4
- Moss, TS 1952, Photoconductivity in the Elements, Butterworths Scientific, London
- Nakao Y 1992, "Dissolution of noble metals in halogen–halide–polar organic solvent systems", Journal of the Chemical Society, Chemical Communications, no. 5, doi:10.1039/C39920000426
- Nash CS 2005, "Atomic and molecular properties of elements 112, 114, and 118", Journal of Physical Chemistry A, vol. 109, doi:10.1021/jp050736o
- National Center for Biotechnology Information 2021, "PubChem compound summary for CID 402, Hydrogen sulfide", accessed August 31, 2021
- National Institute of Standards and Technology 2013, SRM 4972 – Radon-222 Emanation Standard, retrieved from the Internet Archive, August 1, 2021
- National Physical Laboratory, Kaye and Laby Tables of Physical and Chemical Constants, section 3.4.4, Vapour pressures from 0.2 to 101.325 kPa, accessed July 22, 2021
- Nelson PG 1987, "Important elements", Journal of Chemical Education, vol. 68, no. 9, doi:10.1021/ed068p732
- Neuburger MC 1936, 'Gitterkonstanten für das Jahr 1936' (in German), Zeitschrift für Kristallographie, vol. 93, pp. 1–36, ISSN 0044-2968
- Oderberg DS 2007, Real Essentialism, Routledge, New York, ISBN 978-1-134-34885-5
- Oganov et al. 2009, "Ionic high-pressure form of elemental boron", Nature, vol. 457, doi:10.1038/nature07736, arXiv:0911.3192, PMID 19182772
- Okajima Y & Shomoji M 1972, "Viscosity of dilute amalgams", Transactions of the Japan Institute of Metals, vol. 13, no. 4, pp. 255–58, doi:10.2320/matertrans1960.13.255
- Ostriker JP & Steinhardt PJ 2001, "The quintessential universe", Scientific American, vol. 284, no. 1, pp. 46–53 PMID 11132422, doi: 10.1038/scientificamerican0101-46
- Oxford English Dictionary, accessed October 19, 2021
- Oxtoby DW, Gillis HP & Butler LJ 2015, Principles of Modern Chemistry, 8th ed., Cengage Learning, Boston, ISBN 978-1-305-07911-3
- Parameswaran et al. 2020, "Phase evolution and characterization of mechanically alloyed hexanary Al16.6Mg16.6Ni16.6Cr16.6Ti16.6Mn16.6 high entropy alloy", Metal Powder Report, vol. 75, no. 4, doi:10.1016/j.mprp.2019.08.001
- Parish RV 1977, The Metallic Elements, Longman, London, ISBN 978-0-582-44278-8
- Partington JR 1944, A Text-book of Inorganic Chemistry, 5th ed., Macmillan & Co., London
- Pearson WB 1972, The Crystal Chemistry and Physics of Metals and Alloys, Wiley-Interscience, New York, ISBN 978-0-471-67540-2
- Phillips CSG & Williams RJP 1965, Inorganic Chemistry, vol. 1, Principles and non-metals, Clarendon Press, Oxford
- Pilar FL 1979, Chemistry: The Universal Science, Addison-Wesley, Reading, Massachusetts, ISBN 978-0-201-05768-3
- Piro NA, Figueroa JS, McKellar JT & Troiani CC 2006, "Triple-bond reactivity of diphosphorus molecules", Science, vol. 313, no. 5791, doi:10.1126/science.1129630, PMID 16946068
- Pitts CR, Holl MG & Lectka T 2018, "Spectroscopic characterization of a [C−F−C]+ fluoronium ion in solution", Angewandte Chemie International Edition, vol. 57, doi:10.1002/anie.201712021
- Pitzer K 1975, "Fluorides of radon and elements 118", Journal of the Chemical Society, Chemical Communications, no. 18, doi:10.1039/C3975000760B
- Porterfield WW 1993, Inorganic chemistry, Academic Press, San Diego, ISBN 978-0-12-562980-5
- Povh B & Rosina M 2017, Scattering and Structures: Essentials and Analogies in Quantum Physics, 2nd ed., Springer, Berlin, doi:10.1007/978-3-662-54515-7
- Prinessa C & Sadler PJ 2015, "The elements of life and medicines", Philosophical Transactions of the Royal Society A, vol. 373, no. 2037, doi:10.1098/rsta.2014.0182, PMID 25666066, PMC 4342972
- Puddephatt RJ & Monaghan PK 1989, The Periodic Table of the Elements, 2nd ed., Clarendon Press, Oxford, ISBN 978-0-19-855516-2
- Pyykkö P 2012, "Relativistic effects in chemistry: More common than you thought", Annual Review of Physical Chemistry, vol. 63, doi:10.1146/annurev-physchem-032511-143755, PMID 22404585
- Rahm M, Hoffmann R & Ashcroft NW 2016. "Atomic and ionic radii of elements 1–96", Chemistry: A European Journal, vol. 22, doi:10.1002/chem.201602949
- Rao KY 2002, Structural Chemistry of Glasses, Elsevier, Oxford, ISBN 978-0-08-043958-7
- Rao CNR & Ganguly PA 1986, "New criterion for the metallicity of elements", Solid State Communications, vol. 57, no. 1, p. 5–6, doi:10.1016/0038-1098(86)90659-9
- Raub CJ & Griffith WP 1980, "Osmium and sulphur", in Gmelin Handbook of Inorganic Chemistry, 8th ed., Os, Osmium: Supplement, Swars K, (ed.), system no. 66, Springer-Verlag, Berlin, pp. 166–170, ISBN 3-540-93420-0
- Rayner-Canham G 2011, "Isodiagonality in the periodic table", Foundations of Chemistry, vol. 13, no. 2, doi:10.1007/s10698-011-9108-y
- Rayner-Canham G 2018, "Organizing the transition metals", in Scerri E & Restrepo G, Mendeleev to Oganesson: A multidisciplinary perspective on the periodic table, Oxford University, New York, ISBN 978-0-190-668532
- Rayner-Canham 2021, The Periodic Table: Past, Present and Future, World Scientific, New Jersey, ISBN 978-981-121-850-7
- Rees A (ed.) 1819, The Cyclopaedia; Or, an Universal Dictionary of Arts, Sciences, and Literature In Thirty-nine Volumes. Ta – Toleration, vol. 35, Longman, Hurst, Rees, Orme and Brown, London
- Regnault MV 1853, Elements of Chemistry, vol. 1, 2nd ed., Clark & Hesser, Philadelphia
- Reilly C 2002, Metal Contamination of Food, Blackwell Science, Oxford, ISBN 978-0-632-05927-0
- Reinhardt et al. 2015, Inerting in the chemical industry, Linde, Pullach, Germany, accessed October 19 2021
- Remy H 1956, Treatise on Inorganic Chemistry, Anderson JS (trans.), Kleinberg J (ed), vol. II, Elsevier, Amsterdam
- Renouf E 1901, "Lehrbuch der anorganischen Chemie", Science, vol. 13, no. 320, doi:10.1126/science.13.320.268
- Restrepo G, Llanos EJ & Mesa H 2006, "Topological space of the chemical elements and its properties", Journal of Mathematical Chemistry, vol. 39, doi:10.1007/s10910-005-9041-1
- Riley et al. 2020, "Heavy metals make a chain: A catenated bismuth compound", European Chemistry Journal, vol. 26, doi:10.1002/chem.202001295, PMID 32298506
- Ritter SK 2011, "The case of the missing xenon", Chemical & Engineering News, vol. 89, no. 9, ISSN 0009-2347
- Rochow EG 1966, The Metalloids, DC Heath and Company, Boston
- Rochow EG 1973, "Silicon", in Bailar et al. (eds.), Comprehensive Inorganic Chemistry, vol. 1, Pergamon Press, Oxford, ISBN 978-0-08-015655-2
- Rochow EG 1977, Modern Descriptive Chemistry, Saunders, Philadelphia, ISBN 978-0-7216-7628-9
- Rodgers GE 2012, Descriptive Inorganic, Coordination, and Solid State Chemistry, 3rd ed., Brooks/Cole, Belmont, California, ISBN 978-0-8400-6846-0
- Roher GS 2001, Structure and Bonding in Crystalline Materials, Cambridge University Press, Cambridge, ISBN 978-0-521-66379-3
- Royal Society of Chemistry 2021, Periodic Table: Non-metal, accessed September 3, 2021
- Royal Society of Chemistry and Compound Interest 2013, Elements infographics, Group 4 – The Crystallogens, accessed September 2, 2021
- Rudolph J 1974, Chemistry for the Modern Mind, Macmillan, New York
- Ruff O & Kwasnik W 1935, "The fluorination of nitric acid. The nitroxyfluoride, NO3F", Angewandte Chemie, vol. 48, pp. 238–240, doi:10.1002/ange.19350481604
- Russell AM & Lee KL 2005, Structure-Property Relations in Nonferrous Metals, Wiley-Interscience, New York, ISBN 0-471-64952-X
- Sanderson RT 1957, "An electronic distinction between metals and nonmetals", Journal of Chemical Education, vol. 34, no. 5, doi:10.1021/ed034p229
- Sanderson RT 1967, Inorganic Chemistry, Reinhold, New York
- Scerri E (ed.) 2013, 30-Second Elements: The 50 Most Significant Elements, Each Explained In Half a Minute, Ivy Press, London, ISBN 978-1-84831-616-4
- Scerri E 2013, A Tale of Seven Elements, Oxford University Press, Oxford, ISBN 978-0-19-539131-2
- Scerri E 2020, The Periodic Table, Its Story and Its Significance, 2nd ed., Oxford University Press, New York, ISBN 978-0-19-091436-3 |group=n}}
- Schaefer JC 1968, "Boron" in Hampel CA (ed.), The Encyclopedia of the Chemical Elements, Reinhold, New York
- Schenk J & Prins J 1953, "Plastic sulfur", Nature, vol. 172, doi:10.1038/172957a0
- Schmedt auf der Günne J, Mangstl M & Kraus F 2012, "Occurrence of difluorine F2 in nature—In situ proof and quantification by NMR spectroscopy", Angewandte Chemie International Edition, vol. 51, no. 31, doi:10.1002/anie.201203515
- Schulze-Makuch D & Irwin LN 2008, Life in the Universe: Expectations and Constraints, 2nd ed., Springer-Verlag, Berlin, ISBN 978-3-540-76816-6
- Schweitzer GK & Pesterfield LL 2010, The Aqueous Chemistry of the Elements, Oxford University Press, Oxford, ISBN 978-0-19-539335-4
- Science Learning Hub–Pokapū Akoranga Pūtaiao 2021, "The essential elements", accessed August 14, 2021
- Scott D 2015, Around the World in 18 Elements, Royal Society of Chemistry, e-book, ISBN 978-1-78262-509-4
- Scott EC & Kanda FA 1962, The Nature of Atoms and Molecules: A General Chemistry, Harper & Row, New York
- Seaborg GT 1969, "Prospects for further considerable extension of the periodic table", Journal of Chemical Education, vol. 46, no. 10, doi:10.1021/ed046p626
- Seese WS & Daub GH 1985, Basic Chemistry, 4th ed., Prentice-Hall, Englewood Cliffs, NJ, ISBN 978-0-13-057811-2
- Shakhashiri BZ, Dirreen E & Williams LG 1989, "Paramagnetism and color of liquid oxygen: A lecture demonstration", Journal of Chemical Education, vol. 57, no. 5, doi:10.1021/ed057p373
- Shanabrook BV, Lannin JS & Hisatsune IC 1981, "Inelastic light scattering in a onefold-coordinated amorphous semiconductor", Physical Review Letters, vol. 46, no. 2, 12 January, doi:10.1103/PhysRevLett.46.130
- Sharp DWA 1981, 'Metalloids', in Miall's Dictionary of Chemistry, 5th ed, Longman, Harlow, ISBN 0-582-35152-9
- Shiell et al. 2021, "Bulk crystalline 4H-silicon through a metastable allotropic transition", Physical Review Letters, vol. 26, p 215701, doi:10.1103/PhysRevLett.126.215701
- Sidorov TA 1960, "The connection between structural oxides and their tendency to glass formation", Glass and Ceramics, vol. 17, no. 11, doi:10.1007BF00670116
- Siebring BR & Schaff ME 1980, General Chemistry, Wadsworth Publishing, Belmont, CA, ISBN 978-0-534-00802-4
- Siekierski S & Burgess J 2002, Concise Chemistry of the Elements, Horwood Press, Chichester, ISBN 978-1-898563-71-6
- Slye OM Jr 2008, "Fire extinguishing agents", in Ullmann's Encyclopedia of Industrial Chemistry, doi:10.1002/14356007.a11_113.pub2
- Smith A & Dwyer C 1991, Key Chemistry: Investigating Chemistry in the Contemporary World: Book 1: Materials and Everyday Life, Melbourne University Press, Carlton, Victoria, ISBN 978-0-522-84450-4
- Smulders E & Sung E 2011, "Laundry Detergents, 2, Ingredients and Products’’, In Ullmann's Encyclopedia of Industrial Chemistry, doi:10.1002/14356007.o15_o13
- Stein L 1969, "Oxidized radon in halogen fluoride solutions", Journal of the American Chemical Society, vol. 19, no. 19, doi:10.1021/ja01047a042
- Stein L 1983, "The chemistry of radon", Radiochimica Acta, vol. 32, doi:10.1524/ract.19126.96.36.199
- Stellman JM (ed.) 1998, Encyclopaedia of Occupational Health and Safety, vol. 4, 4th ed., International Labour Office, Geneva, ISBN 978-92-2-109817-1
- Steudel R 1977, Chemistry of the Non-metals: With an Introduction to atomic Structure and Chemical Bonding, Walter de Gruyter, Berlin, ISBN 978-3-11-004882-7
- Steudel R & Eckert B 2003, "Solid sulfur allotropes", in Steudel R (ed.), Elemental Sulfur and Sulfur-rich Compounds I, Springer-Verlag, Berlin, ISBN 978-3-540-40191-9
- Steurer W 2007, "Crystal structures of the elements" in Marin JW (ed.), Concise Encyclopedia of the Structure of Materials, Elsevier, Oxford, ISBN 978-0-08-045127-5
- Stewart D, Chemicool Periodic Table, www.chemicool.com. accessed July 10, 2021
- Stott RWA 1956, Companion to Physical and Inorganic Chemistry, Longmans, Green and Co, London
- Su et al. 2020, "Advances in photonics of recently developed Xenes", Nanophotonics, vol. 9, no. 7, doi:10.1515/nanoph-2019-0561
- Suresh CH & Koga NA 2001, "A consistent approach toward atomic radii”, Journal of Physical Chemistry A, vol. 105, no. 24. doi:10.1021/jp010432b
- Sutton M 2016, "A noble quest", Chemistry World, September 9, accessed September 8, 2021
- Szpunar J, Bouyssiere B & Lobinski R 2004, 'Advances in Analytical Methods for Speciation of Trace Elements in the Environment', in AV Hirner & H Emons (eds), Organic Metal and Metalloid Species in the Environment: Analysis, Distribution Processes and Toxicological Evaluation, Springer-Verlag, Berlin, pp. 17–40, ISBN 978-3-540-20829-7
- Tantardini C & Oganov AR 2021, "Thermochemical electronegativities of the elements", Nature Communications, vol. 12, article no. 2087, doi:10.1038/s41467-021-22429-0, PMID 33828104, PMC 8027013
- The Chemical News and Journal of Physical Science 1864, "Notices of books: Manual of the Metalloids", Jan 9
- The Chemical News 1897, "Notices of books: A Manual of Chemistry, Theoretical and Practical, by WA Tilden", vol. 75, no. 1951
- Thornton BF & Burdette SC 2010, "Finding eka-iodine: Discovery priority in modern times", Bulletin for the history of chemistry, vol. 35, no. 2, accessed September 14, 2021
- Tregarthen L 2003, Preliminary Chemistry, Macmillan Education: Melbourne, ISBN 978-0-7329-9011-4
- Trenberth KE & Smith L 2005, "The mass of the atmosphere: A constraint on global analyses", Journal of Climate, vol. 18, no. 6, doi:10.1175/JCLI-3299.1
- Tshitoyan et al. 2019, "Unsupervised word embeddings capture latent knowledge from materials science literature." Nature, vol. 571, doi:10.1038/s41586-019-1335-8
- Tyler PM 1948, From the Ground Up: Facts and Figures of the Mineral Industries of the United States, McGraw-Hill, New York
- Van Setten et al. 2007, "Thermodynamic stability of boron: The role of defects and zero point motion", Journal of the American Chemical Society, vol. 129, no. 9, doi:10.1021/ja0631246
- Vassilakis AA, Kalemos A & Mavridis A 2014, "Accurate first principles calculations on chlorine fluoride ClF and its ions ClF±", Theoretical Chemistry Accounts, vol. 133, article no. 1436, doi:10.1007/s00214-013-1436-7
- Vernon R 2013, "Which elements are metalloids?", Journal of Chemical Education, vol. 90, no. 12, 1703‒1707, doi:10.1021/ed3008457
- Vernon R 2020, "Organising the metals and nonmetals", Foundations of Chemistry, vol. 22, doi:10.1007/s10698-020-09356-6
- Vernon R 2021, "The location and constitution of Group 3 of the periodic table", Foundations of Chemistry, vol. 23, doi:10.1007/s10698-020-09384-2
- Wächtershäuser G 2014, "From chemical invariance to genetic variability", in Weigand W and Schollhammer P (eds), Bioinspired Catalysis: Metal Sulfur Complexes, Wiley-VCH, Weinheim, doi:10.1002/9783527664160.ch1
- Walker P & Tarn WH 1996, CRC Handbook of Metal Etchants, Boca Raton, FL, ISBN 978-0-8493-3623-2
- Wakeman TH 1899, "Free thought—Past, present and future", Free Thought Magazine, vol. 17
- Watts H 1871, A Dictionary of Chemistry and the Allied Branches of Other Sciences, vol. 3, Longmans, Green, and Co, London, p. 934
- Weeks ME 1948, Discovery of the Elements, 5th ed., Journal of Chemical Education, Easton, Pennsylvania
- Welcher SH 2001, High marks: Regents Chemistry Made Easy, 2nd ed., High Marks Made Easy, New York, ISBN 978-0-9714662-4-1
- Wells AF 1984, Structural Inorganic Chemistry, 5th ed., Clarendon Press, Oxford, ISBN 978-0-19-855370-0
- West DC 1953, "The photoelectric constants of iodine", Canadian Journal of Physics, vol. 31, no. 5, doi:10.1139/p53-065
- White JH 1962, Inorganic Chemistry: Advanced and Scholarship Levels, University of London Press, London
- Wiberg N 2001, Inorganic Chemistry, Academic Press, San Diego, ISBN 978-0-12-352651-9
- Wickleder MS, Pley M & Büchner O 2006, 'Sulfates of precious metals: Fascinating chemistry of potential materials', Zeitschrift für Anorganische und Allgemeine Chemie, vol. 632, nos. 12–13, p. 2080, doi:10.1002/zaac.200670009
- Wickleder MS 2007, "Chalcogen-oxygen chemistry", in Devillanova FA (ed.), Handbook of Chalcogen Chemistry: New Perspectives in Sulfur, Selenium and Tellurium, RSC, Cambridge, pp. 344–377, ISBN 978-0-85404-366-8
- Williams RPJ 2007, "Life, the environment and our ecosystem", Journal of Inorganic Biochemistry, vol. 101, nos. 11–12, doi:10.1016/j.jinorgbio.2007.07.006
- Windmeier C & Barron RF 2013, "Cryogenic technology", in Ullmann's Encyclopedia of Industrial Chemistry, doi:10.1002/14356007.b03_20.pub2
- Winkler et al. 2016, "The diverse biological properties of the chemically inert noble gases", Pharmacology & Therapeutics, vol. 160, doi:10.1016/j.pharmthera.2016.02.002
- Winstel G 2000, Electroluminescent materials and devices, in Ullmann's Encyclopedia of Industrial Chemistry, doi:10.1002/14356007.a09_255
- Woodward et al. 1999, "The electronic structure of metal oxides". In Fierro JLG (ed.), Metal Oxides: Chemistry and Applications, CRC Press, Boca Raton, ISBN 1-4200-2812-X
- Wulfsberg G 1987, Principles of Descriptive Chemistry, Brooks/Cole, Belmont CA, ISBN 978-0-534-07494-4
- Wulfsberg G 2000, Inorganic Chemistry, University Science Books, Sausalito, California, ISBN 978-1-891389-01-6
- Yamaguchi M & Shirai Y 1996, "Defect strutures", in Stoloff NS & Sikka VK (eds) Physical Metallurgy and Processing of Intermetallic Compounds, Chapman & Hall, New York, ISBN 978-1-4613-1215-4
- Yoder CH, Suydam FH & Snavely FA 1975, Chemistry, 2nd ed, Harcourt Brace Jovanovich, New York, ISBN 978-0-15-506470-6
- Yost DM & Russell H 1946, Systematic Inorganic Chemistry of the Fifth-and-Sixth-Group Nonmetallic Elements, Prentice-Hall, New York
- Young et al. Botch B 2018, General Chemistry: Atoms First, Cengage Learning: Boston, ISBN 978-1-337-61229-6
- Young JA 2006, "Iodine", Journal of Chemical Education, vol. 83, no. 9, doi:10.1021/ed083p1285
- Yousuf M 1998, "Diamond anvil cells in high-pressure studies of semiconductors", in Suski T & Paul W (eds), High Pressure in Semiconductor Physics II, Semiconductors and Semimetals, vol. 55, Academic Press, San Diego, ISBN 978-0-08-086453-2
- Zhao, Z, Zhang H, Kim D. et al. 2017, "Properties of the exotic metastable ST12 germanium allotrope", Nature Communications, vol. 8, doi:10.1038/ncomms13909, PMID 28045027, PMC 5216117
- Zhu et al. 2014, "Reactions of xenon with iron and nickel are predicted in the Earth's inner core", Nature Chemistry, vol. 6, doi:10.1038/nchem.1925, PMID 24950336
- Zoroddu et al. 2019, "The essential metals for humans: a brief overview", Journal of Inorganic Biochemistry, vol. 195, doi:10.1016/j.jinorgbio.2019.03.013, PMID 30939379
- Zumdahll SS & DeCoste DJ 2019, Introductory Chemistry: A Foundation, 9th ed., Cengage Learning, Boston, ISBN 978-1-337-39942-5
- Zumdahl SS & Zumdahl SA 2009, Chemistry, 7th ed., Houghton Mifflin, Boston, ISBN 978-1-111-80828-0
- Steudel R 2020, Chemistry of the Non-metals: Syntheses - Structures - Bonding - Applications, in collaboration with D Scheschkewitz, Berlin, Walter de Gruyter, doi:10.1515/9783110578065.
- Twenty-three nonmetals, including B, Si, Ge, As, Se, Te, and At but not Sb (nor Po). The nonmetals are identified on the basis of their electrical conductivity at absolute zero putatively being close to zero, rather than finite as in the case of metals. That does not work for As however, which has the electronic structure of a semimetal (like Sb).
- Halka M & Nordstrom B 2010, "Nonmetals", Facts on File, New York, ISBN 978-0-8160-7367-2
- A reading level 9+ book covering H, C, N, O, P, S, Se. Complementary books by the same authors examine (a) the post-transition metals (Al, Ga, In, Tl, Sn, Pb and Bi) and metalloids (B, Si, Ge, As, Sb, Te and Po); and (b) the halogens and noble gases.
- Woolins JD 1988, Non-Metal Rings, Cages and Clusters, John Wiley & Sons, Chichester, ISBN 978-0-471-91592-8.
- A more advanced text that covers H; B; C, Si, Ge; N, P, As, Sb; O, S, Se and Te.
- Steudel R 1977, Chemistry of the Non-metals: With an Introduction to Atomic Structure and Chemical Bonding, English edition by FC Nachod & JJ Zuckerman, Berlin, Walter de Gruyter, ISBN 978-3-11-004882-7.
- Twenty-three nonmetals, including B, Si, Ge, As, Se, Te, and Po.
- Powell P & Timms PL 1974, The Chemistry of the Non-metals, Chapman & Hall, London, ISBN 978-0-470-69570-8.
- Twenty-two nonmetals including B, Si, Ge, As and Te. Tin and antimony are shown as being intermediate between metals and nonmetals; they are later shown as either metals or nonmetals. Astatine is counted as a metal.
- Emsley J 1971, The Inorganic Chemistry of the Non-metals, Methuen Educational, London, ISBN 978-0-423-86120-4.
- Twenty nonmetals. H is placed over F; B and Si are counted as nonmetals; Ge, As, Sb and Te are counted as metalloids.
- Johnson RC 1966, Introductory Descriptive Chemistry: Selected Nonmetals, their Properties, and Behavior, WA Benjamin, New York.
- Eighteen nonmetals. H is shown floating over B and C. Silicon, Ge, As, Sb, Te, Po and At are shown as semimetals. At is later shown as a nonmetal (p. 133).
- Jolly WL 1966, The Chemistry of the Non-metals, Prentice-Hall, Englewood Cliffs, New Jersey.
- Twenty-four nonmetals, including B, Si, Ge, As, Sb, Te and At. H is placed over F.
- Sherwin E & Weston GJ 1966, Chemistry of the Non-metallic Elements, Pergamon Press, Oxford.
- Twenty-three nonmetals. H is shown over Li and F; Germanium, As, Se, and Te are later referred to as metalloids; Sb is shown as a nonmetal but later referred to as a metal. They write, "Whilst these heavier elements [Se and Te] look metallic they show the chemical properties of non-metals and therefore come into the category of "metalloids" (p. 64).
- Phillips CSG & Williams RJP 1965, Inorganic Chemistry, vol. 1, Principles and non-metals, Oxford University Press, Clarendon.
- Twenty-three nonmetals, excluding Sb, including At. An advanced work for its time, presenting inorganic chemistry as the difficult and complex subject it was, with many novel insights.
- Yost DM & Russell Jr, H 1946 Systematic Inorganic Chemistry of the Fifth-and-Sixth-Group Nonmetallic Elements, Prentice-Hall, New York, accessed August 8, 2021.
- Includes tellurium as a nonmetallic element.
- Bailey GH 1918, The Tutorial Chemistry, Part 1: The Non-Metals, 4th ed., W Briggs (ed.), University Tutorial Press, London.
- Fourteen nonmetals (excl. the noble gases), including B, Si, Se, and Te. The author writes that arsenic and antimony resemble metals in their luster and conductivity of heat and electricity but that in their chemical properties they resemble the non-metals, since they form acidic oxides and insoluble in dilute mineral acids; "such elements are called metalloids" (p. 530).
- Appleton JH 1897, The Chemistry of the Non-metals: An Elementary Text-Book for Schools and Colleges, Snow & Farnham Printers, Providence, Rhode Island
- Eighteen nonmetals: He, Ar; F, Cl, Br, I; O, S, Se, Te; N, P, As, Sb; C, Si; B; H. Neon, germanium, krypton and xenon are listed as new or doubtful elements. For Sb, Appleton writes:
- "Antimony is sometimes classed as a metal, sometimes as a non-metal. In case of several other elements the question of classification is difficult—indeed, the classification is one of convenience, in a sense, more than one of absolute scientific certainty. In some of its relations, especially its physical properties, antimony resembles the well-deﬁned metals—in its chemical relations, it falls into the group containing boron, nitrogen, phosphorus, arsenic, well-deﬁned non-metals." (p. 166).
- Appleton JH 1888, Beginners' Hand-book of Chemistry: The Subject Developed by Facts and Principles Drawn Chiefly from the Non-metals, Chautauqua Press, New York.
- Fifteen nonmetals including B, Si, As, Sb and Se (the six noble gases were not then known; Ge had only been discovered in 1886). Te is shown in a list of the chemical elements but not mentioned elsewhere.
- Gmelin L 1849, Handbook of Chemistry, vol. 2, Non-metallic elements, H Watts (trans.), Cavendish Society, London.
- Twelve nonmetals (then called "metalloids"): H, B, C, N, O, F, P, S, Cl, Se, Br, I.
- Media related to Nonmetals at Wikimedia Commons