Nonmetal

Summary

A periodic table showing 14 elements listed by nearly all authors as nonmetals (the noble gases plus fluorine, chlorine, bromine, iodine, nitrogen, oxygen, and sulfur); 3 elements listed by most authors as nonmetals (carbon, phosphorus and selenium); and 6 elements listed as nonmetals by some authors (boron, silicon, germanium, arsenic, antimony).
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Extract (above) of periodic table (below) showing how often each element is classed nonmetalic:
 14  effectively always[1]
 3  frequently
 6  sometimes[2]
(gray letters and boxes: metals)

Hydrogen is usually in group 1 (as in this full table) but can be in group 17 (as in the extract).[n 1]

In chemistry, nonmetals are a class of chemical elements whose chemical and physical properties contrast with those of metals. Most nonmetals gain electrons when reacting with a metal, form an acid if combined with oxygen and hydrogen, and are poor conductors of heat and electricity.[n 2] Nonmetals display more variety in color and state than do metals. About half are colored or colorless gases whereas nearly all metals are silvery-gray solids. Unlike most metals, they tend to have no structural uses.[6]

While the term dates from at least 1708, it has no widely-agreed precise definition.[7] Consequently, which elements are recognised as nonmetals depends on the classification criteria used by each author. Fourteen elements are effectively always included. Up to about nine more elements are frequently to sometimes added.[8]

Two nonmetals, hydrogen and helium, make up about 99% of ordinary (baryonic) matter in the observable universe by mass.[9] Three nonmetallic elements, hydrogen, oxygen and silicon, largely make up the Earth's crust, atmosphere, oceans and biosphere.[10][11] This is so even though the number of nonmetal elements is several times lower than the number of metal elements.

Most nonmetals have biological, technological or domestic roles or uses. Living organisms are composed almost entirely of the nonmetals hydrogen, oxygen, carbon, and nitrogen.[12] Near-universal uses for nonmetals are in medicine and pharmaceuticals;[13] lasers and lighting;[14] and household items.[15]

Definition and applicable elements

There is no rigorous definition of a nonmetal.[16] Broadly, any element lacking a preponderance of metallic properties such as luster, deformability, and good electrical conductivity, can be regarded as a nonmetal.[17] Nevertheless some variation may be encountered among authors as to which elements are regarded as nonmetals, especially where the metals meet the nonmetals in periodic table terms.[18] This lack of consistency occurs due to the absence of a universally agreed criterion or set of criteria for distinguishing between metals and nonmetals. Classification decisions of individual authors then become subject to which property or properties they regard as being most indicative of metallic or nonmetallic character.[8]

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. Up to a further nine elements are sometimes or usually considered 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.[4]

Astatine, the fifth halogen, is often ignored on account of its rarity and intense radioactivity;[19] the theoretical and experimental evidence is indirect, but strongly suggests that it is a metal. The superheavy elements copernicium (Z = 112) and oganesson (118) may turn out to be nonmetals; their actual status has not yet been confirmed.[20]

Since there are 118 known elements,[21] as of October 2021, the nonmetals are outnumbered by the metals several times.

Concept origin, distinguishing criteria, and use of term

Origin of the concept

The distinction between metals and nonmetals arose, in a convoluted manner, from a crude recognition of natural kinds of matter. Thus:

  • matter could be divided into pure substances and mixtures;
  • pure substances eventually could be distinguished as compounds and elements;
  • "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, for example as occurred with quicklime (CaO).[29]

Distinguishing criteria

An example algorithm
distinguishing metals and nonmetals
[30][31][32]
1. If an element is an electrical insulator or semiconductor it is a nonmetal
2. If it is soft and crumbly and forms an oxide with nitric acid it is a nonmetal (C, As, Sb)
3. All other elements, whether soft and crumbly (Ga, Bi);[n 3] ductile and malleable; hard and brittle; or liquid (Hg), are metals
Although ontologically, anything not a metal is a "nonmetal", some authors divide the elements into metals, metalloids, and nonmetals.[33]

Many different properties have been used in attempts to refine the distinction between metals and nonmetals, including:

Johnson[39] 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 et al.[8] 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"[55] is established, the nonmetals are found to be those lacking the properties of metals,[56] to greater or lesser degrees.[57]

Use of the term

The term "nonmetallic" dates from as far back as 1708 when Wilhelm Homberg mentioned "non-metallic sulfur" in his Des Essais de Chimie.[58] He had refuted the five-fold division of matter into sulfur, mercury, salt, water and earth, previously in vogue, as postulated by Étienne de Clave [fr] (1641) in New Philosophical Light of True Principles and Elements of Nature. Homberg's approach represented "an important move toward the modern concept of an element".[59] Subsequently, the first modern list of chemical elements was given by Lavoisier in his "revolutionary"[60] 1789 work Traité élémentaire de chimie in which he distinguished between simple metallic and nonmetallic substances. In its first seventeen years, Lavoisier's work was republished in twenty-three editions and six languages, and carried his "new chemistry" across Europe and America.[61]

General properties

Physical

Metals tend to have closer-packed structures. Nonmetals are more open-packed. Values for nonmetals that are normally gases are for the liquid state at boiling point.[n 4]

Physically, nonmetals in their most stable forms exist as either polyatomic solids (carbon, for example) with open-packed crystalline structures; 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.[64] Solid nonmetals are brittle, as opposed to metals, which are 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.[65]

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 (free to move between atoms) and metallic properties are predicted. Otherwise nonmetallic properties are anticipated.[66]

Chemical

Chemically, nonmetals mostly have higher ionization energies, higher electron affinities, higher electronegativity values, and higher standard reduction potentials than metals. Here, and in general, the higher these values, the more nonmetallic is the element in question.[67]

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 electron configurations of the noble gases (filled valence shells), 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. 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.[68] 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).[32]

Some typical chemistry-based
differences between metals and nonmetals[69]
Aspect Metals Nonmetals
Chemical
bonding
Seldom form
covalent bonds
Frequently form
covalent bonds
Metallic bonds (alloys)
between metals
Covalent bonds
between nonmetals
Ionic bonds between nonmetals and metals
Oxidation
states
Positive Negative or positive
Oxides Basic in lower oxides;
increasingly acidic
in higher oxides
Acidic
In aqueous
solution
[70]
Exist as anions
or oxyanions
Exist as cations

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.[71] There is an associated reduction in atomic radius[72] as the increasing nuclear charge draws the valence electrons closer to the core.[73] In metals, the effect of the nuclear charge is generally weaker than for 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.[74]

The number of compounds formed by nonmetals is vast.[75] The first ten places in a "top 20" table of elements most frequently encountered in 895,501,834 compounds, as listed in the Chemical Abstracts Service register for November 2nd, 2021, were occupied by nonmetals. Hydrogen, carbon, oxygen and nitrogen were found in the majority (80%) of compounds. Silicon, a metalloid, was in 11th place. The highest rated metal, with an occurrence frequency of 0.14%, was iron, in 12th place.[76] Examples of nonmetal compounds are: boric acid (H
3
BO
3
), used in ceramic glazes; selenocysteine (C
3
H
7
NO
2
Se
), the 21st amino acid of life;[77] phosphorus sesquisulfide (P4S3), in strike anywhere matches; and teflon ((C
2
F
4
)n).[78]

Complications

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;[79] and unusual valence states in the heavier nonmetals. In this regard, Zuckerman and Nachod opined that:

The marvellous variety and infinite subtlety of the nonmetallic elements, their compounds, structures and reactions, is not sufficiently acknowledged in the current teaching of chemistry.[80]
H and He are in the first row of the s-block. B through Ne take up the first row of the p-block. Sc through Zn occupy the first row of the d-block. La to Yb make up the first row of the f block.
Periodic table highlighting the first row of each block. Helium (He), as a noble gas, is normally shown over neon (Ne) with the rest of the noble gases. The elements within scope of this article are inside the thick black borders. The status of oganesson (Og) is not yet known.

First row anomaly. Starting with hydrogen, 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.[81] 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.[82] 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."[83]

A graph with a vertical electronegativity axis and a horizontal atomic number axis. The five elements plotted are O, S, Se, Te and Po. The electronegativity of Se looks too high, and causes a bump in what otherwise be a smooth curve.
Electronegativity values of the group 16 chalcogen elements showing a W-shaped alternation or secondary periodicity going down the group

For hydrogen and helium, and from boron to neon, since the 1s and 2p subshells have no inner analogues (i.e., there is no zeroth shell and no 1p subshell) and therefore experience no electron repulsion effects, they have relatively small radii, unlike the 3p, 4p and 5p subshells of heavier elements.[84] 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 double or triple bonds.[85]

Secondary periodicity. Immediately after the first row of the transition metals, the 3d electrons in the 4th row of elements, i.e., in gallium (a metal), germanium, arsenic, selenium, and bromine, are not as effective at shielding the increased nuclear charge. A similar effect accompanies the appearance of fourteen f-block metals between barium and lutetium, ultimately resulting in smaller than expected atomic radii for the elements from hafnium (Hf) onwards.[86] 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.[87]

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).[88]

Subclasses

Modern periodic table extract showing nonmetal subclasses.
moderately strong oxidising agent ‡ strong oxidising agent[n 5]

Historical

A basic taxonomy of nonmetals was set out in 1844, by Alphonse Dupasquier, a French doctor, pharmacist and chemist.[99] To facilitate the study of nonmetals, he wrote:[100]

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.

Dupasquier's organogens and sulphuroids correspond to the set of unclassified nonmetals. Eventually thereafter:

  • the chloroide nonmetals came to be independently referred to as halogens;[101]
  • the boroid nonmetals came to expand into the metalloids, starting from as early as 1864;[102]
  • varying configurations of the orgaonogen and the sulphuroid nonmetals have been referred to as, for example, basic nonmetals;[103] biogens;[104] central nonmetals;[105] CHNOPS;[106] essential elements;[107] "nonmetals";[108][n 6] orphan nonmetals;[109] or redox nonmetals;[110]
  • the noble gases, as a discrete grouping, were counted among the nonmetals from as early as 1900.[111]

Current

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";[112] the Royal Society of Chemistry periodic table uses a different color for each of its eight main groups, and nonmetals can be found in seven of these.[113]

From right to left in periodic table terms, three or four kinds of nonmetals are more or less commonly discerned. 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[114] (the term used here) or stable halogens;[115]
  • 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,[116] sometimes considered to be nonmetals and sometimes not.[n 7]

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[118] or as a sub-class of nonmetals;[119] others count some of them as metals, for example arsenic and antimony, due to their similarities to heavy metals.[120][n 8] 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.[122]

Noble gases

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.[123]

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.[124] That is why they are all gases under standard conditions, even those with atomic masses larger than many normally solid elements.[125]

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,[126] with most of these occurring via oxygen or fluorine combining with either krypton, xenon or radon.[127]

In periodic table terms, an analogy can be drawn between the noble gases and noble metals such as platinum and gold, with the latter being similarly reluctant to enter into chemical combination.[128] As a further example, xenon, in the +8 oxidation state, forms a pale yellow explosive oxide, XeO4, while osmium, another noble metal, forms a yellow strongly oxidizing oxide, OsO4; and there are parallels in the formulas of the oxyfluorides: XeO2F4 and OsO2F4, and XeO3F2 and OsO3F2.[129]

Nonmetal halogens

A conventional periodic table showing the positions of the alkali metals (A) and the nonmetal halogens (H).

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.[130]

Physically, fluorine and chlorine are pale yellow and yellowish green gases; bromine is a reddish-brown liquid; and iodine is a metallic-looking (under white light)[131] solid. Electrically, the first three are insulators while iodine is a semiconductor (along its planes).[132]

Chemically, they have high ionization energies, electron affinities, and electronegativity values, and are mostly relatively strong oxidizing agents.[133] Manifestations of this status include their intrinsically corrosive nature.[134] All four exhibit a tendency to form predominately ionic compounds with metals[135] whereas the remaining nonmetals, bar oxygen, tend to form predominately covalent compounds with metals.[n 9] The reactive and strongly electronegative nature of the nonmetal halogens represents the epitome of nonmetallic character.[139]

In periodic table terms, the counterparts of the highly nonmetallic halogens, in group 17 are the highly reactive metals, such as sodium and potassium, in group 1. Curiously most of the alkali metals are known to form –1 anions (something that rarely occurs among nonmetals) as if in imitation of the nonmetal halogens.[140]

Unclassified nonmetals

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); and one is yellow (S). Electrically, graphitic carbon is a semimetal along its planes[141] and a semiconductor in a direction perpendicular to its planes;[142] phosphorus and selenium are semiconductors;[143] and hydrogen, nitrogen, oxygen, and sulfur are insulators.[n 10]

They are generally regarded as being too diverse to merit a collective examination,[145][146] and have been referred to as other nonmetals,[147] or more plainly as nonmetals, located between metalloids and halogens.[148] Consequently, their chemistry tends to be taught disparately, according to their four respective periodic table groups,[149] 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 11]

Hydrogen, in particular, behaves in some respects like a metal and in others like a nonmetal.[151] Like a metal it can (first) lose its single valence electron;[152] it can stand in for alkali metals in typical alkali metal structures;[153] and is capable of forming alloy-like hydrides, featuring metallic bonding, with some transition metals.[154] 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.[155] It does this by way of forming a covalent or ionic bond[154] or, if it has lost its valence electron, attaching itself to a lone pair of electrons.[156]

Some or all of these nonmetals nevertheless have several shared properties. Their physical and chemical character is "moderately non-metallic", on a net basis.[146] Being less reactive than the halogens[157] most of them, except for phosphorus, can occur naturally in the environment.[158] They have prominent biological[159][160] and geochemical roles.[146] When combined with halogens, unclassified nonmetals form (polar) covalent bonds.[161] When combined with metals they can form hard (interstitial or refractory) compounds,[162] in light of their relatively small atomic radii and sufficiently low ionization energy values.[146] Unlike the halogens, unclassified nonmetals show a tendency to catenate, especially in solid-state compounds.[163][146] Diagonal relationships among these nonmetals echo similar relationships among the metalloids.[145][164]

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".[165]

Metalloids

The six elements more commonly recognized as metalloids are boron, silicon, germanium, arsenic, antimony, and tellurium, with each having a metallic appearance. 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.[131]

They are brittle and only fair conductors of electricity and heat. Boron, silicon, germanium and tellurium are semiconductors. Arsenic and antimony have the electronic band structures of semimetals although both have less stable semiconducting allotropes.[131]

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.[131]

Like hydrogen among the unclassified nonmetals, boron is chemically similar to metals in some respects.[166][n 12] It has fewer electrons than orbitals available for bonding. Analogies with transition metals occur in the formation of complexes,[168] and adducts (for example, BH3 + CO →BH3CO and, similarly, Fe(CO)4 + CO →Fe(CO)5),[n 13] as well as in the geometric and electronic structures of cluster species such as [B6H6]2− and [Ru6(CO)18]2−.[170]

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)[171] sometimes referred to as post-transition metals.[172] Dingle explains the situation this way:[173]

…with 'no-doubt' metals on the far left of the table, and no-doubt non-metals on the far right…the gap between the two extremes is bridged first by the poor (post-transition) metals, and then by the metalloids – which, perhaps by the same token, might collectively be renamed the 'poor non-metals'.

Comparison

Properties of metals and those of the (sub)classes of metalloids, unclassified nonmetals, nonmetal halogens, and noble gases are summarized in the table.[n 14] Physical properties apply to elements in their most stable forms in ambient conditions, 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 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[174] solid (Hg is liquid) solid
  • ◇ solid: C, P, S, Se
  • ◇ gaseous: H, N, O
  • ◇ solid: I
  • ◇ liquid: Br
  • ◇ gaseous: F, Cl
gaseous
Appearance lustrous[65] lustrous[175]
  • ◇ lustrous: C, P, Se[176]
  • ◇ colorless: H, N, O[177]
  • ◇ colored: S[178]
colorless[180]
Elasticity mostly malleable and ductile[65] (Hg is liquid) brittle[175]
  • ◇ C, black P, S and Se are brittle[181]
  • ◇ the same four have less stable non-brittle forms[n 15]
iodine is brittle[187] not applicable
Electrical conductivity high[n 16]
  • ◇ moderate: B, Si, Ge, Te
  • ◇ high: As, Sb[n 17]
  • ◇ low: H, N, O, S
  • ◇ moderate: P, Se
  • ◇ high: C[n 18]
  • ◇ low: F, Cl, Br
  • ◇ moderate: I[n 19]
low[n 20]
Electronic structure[192] metallic (Bi is a semimetal) semimetal (As, Sb) or semiconductor
  • ◇ semimetal: C
  • ◇ semiconductor: P, Se
  • ◇ insulator: H, N, O, S
semiconductor (I) or insulator insulator
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
weakly nonmetallic[n 21] moderately nonmetallic[196] strongly nonmetallic[197]
  • ◇ inert to nonmetallic[198]
  • ◇ Rn shows some cationic behavior[199]
Ionization energy (kJ mol−1)†
(data page)
  • ◇ low to high
  • ◇ 376 to 1,007
  • ◇ average 643
  • ◇ moderate
  • ◇ 762 to 947
  • ◇ average 833
  • ◇ moderate to high
  • ◇ 941 to 1,402
  • ◇ average 1,152
  • ◇ high
  • ◇ 1,008 to 1,681
  • ◇ average 1,270
  • ◇ high to very high
  • ◇ 1,037 to 2,372
  • ◇ average 1,589
Electronegativity (Pauling scale)[n 22]
(data page)
  • ◇ very low to moderate
  • ◇ 0.79 to 2.54
  • ◇ average 1.5
  • ◇ low
  • ◇ 1.9 to 2.18
  • ◇ average 2.05
  • ◇ moderate to high
  • ◇ 2.19 to 3.44
  • ◇ average 2.65
  • ◇ high
  • ◇ 2.66 to 3.98
  • ◇ average 3.19
  • ◇ low (Rn) to very high
  • ◇ 2.2 to 5.2
  • ◇ average 3.38
Compounds with metals alloys[65] or intermetallic compounds[201] tend to form alloys or intermetallic compounds[202]
  • ◇ salt-like to covalent: H‡, C, N, P, S, Se[203]
  • ◇ mainly ionic: O[204]
mainly ionic[135] simple compounds in ambient conditions not known[n 23]
Oxides
  • ◇ ionic, polymeric, layer, chain, and molecular structures[206]
  • ◇ V; Mo, W; Al, In, Tl; Sn, Pb; Bi are glass formers[207]
  • ◇ basic; some amphoteric or acidic[208]
  • ◇ mostly molecular[209]
  • ◇ C, P, S, Se are known in at least one polymeric form
  • ◇ P, S, Se are glass formers;[207] CO2 forms a glass at 40 GPa[213]
  • ◇ acidic (NO
    2
    , N
    2
    O
    5
    , SO
    3
    , and SeO
    3
    strongly so)[214][215] or neutral (H2O, CO, NO, N2O)[n 25]
  • ◇ molecular[209]
  • ◇ iodine is known in at least one polymeric form, I2O5[217]
  • ◇ no glass formers reported
  • ◇ acidic; ClO
    2
    , Cl
    2
    O
    7
    , and I
    2
    O
    5
    strongly so[215][214]
  • ◇ molecular[209]
  • XeO2 is polymeric[218]
  • ◇ no glass formers reported
  • ◇ metastable XeO3 is acidic;[219] stable XeO4 strongly so[220]
† The labels low, moderate, high, and very high are arbitrarily based on the value spans listed in the table
‡ Hydrogen can also form alloy-like hydrides
[221]

Most properties show a left-to-right progression in metallic to nonmetallic character or average values. The periodic table can thus be indicatively divided into metals and nonmetals, with more or less distinct gradations seen among the nonmetals.[222]

Allotropes

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.[223]

Among the nonmetal halogens, and unclassified nonmetals:

  • Iodine is known in a semiconducting amorphous form.[224]
  • Graphite, the standard state of carbon, is a fairly good electrical conductor. The diamond allotrope of carbon is clearly nonmetallic, being translucent and, as an insulator, an extremely poor electrical conductor.[225] Carbon is further known in several other allotropic forms, including semiconducting buckminsterfullerene (C60).[226]
  • Nitrogen can form gaseous tetranitrogen (N4), an unstable polyatomic molecule with a lifetime of about one microsecond.[227]
  • Oxygen is a diatomic molecule in its standard state; it also exists as ozone (O3), an unstable nonmetallic allotrope with an "indoors" half-life of around half an hour, compared to about three days in ambient air at 20°C.[228]
  • 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.[229] Phosphorus also exists as diphosphorus (P2), an unstable diatomic allotrope.[230]
  • Sulfur has more allotropes than any other element.[231] Amorphous sulfur, a metastable mixture of such allotropes, is noted for its elasticity.[232]
  • Selenium has several nonmetallic allotropes, all of which are much less electrically conducting than its standard state of gray "metallic" selenium.[233]

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.[234] At a pressure of ca. 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.[235] Arsenic and antimony form several well-known allotropes (yellow, grey, and black). Tellurium is known in its crystalline and amorphous forms.[236]

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 26] starting with phosphorus at 1.7 GPa, have been observed to form metallic allotropes.[237][n 27] 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".[239]

Abundance, occurrence, extraction and cost

Abundance

Hydrogen and helium are estimated to make up approximately 99% of all ordinary matter in the universe and over 99.9% of its atoms.[9] Oxygen is thought to be the next most abundant element, at ca. 0.1%.[240] Less than five per cent 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.[241]

Five nonmetals—hydrogen, carbon, nitrogen, oxygen and silicon—constitute the bulk of the Earth's crust, atmosphere, oceans and biomass, by weight. The crust is largely made up of oxygen (61%) and silicon (20%); the atmosphere is about 78% nitrogen and 21% oxygen; water (H2O) is oxygen and hydrogen, and the world's biomass largely (99.5%) comprises hydrogen, carbon, and oxygen.[10][11][242]

Occurrence

Noble gases

About 1015 tonnes of noble gases are present in the Earth's atmosphere.[243] Helium is additionally found in natural gas to the extent of as much as 7%.[244] Radon further diffuses out of rocks, where it is formed during the natural decay sequence of uranium and thorium.[245] In 2014, it was reported that the Earth's core may contain ca. 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."[246]

Nonmetal halogens

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.[247]

Unclassified nonmetals

a lump of rock, with a large colorless crystal embedded into it
Carbon as diamond, here shown in native form. Diamantine carbon is thermodynamically less stable than graphitic carbon.[248]

Unclassified nonmetals occur typically occur in elemental forms (oxygen, sulfur) or are found in association with either of these two elements:[249]

  • Hydrogen occurs in the world's oceans as a component of water, and in natural gas as a component of methane and hydrogen sulfide.[250]
  • Carbon occurs in limestone, dolomite, and marble, as carbonates.[251] Less well known is carbon as graphite, which mainly occurs in metamorphic silicate rocks[252] 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.[253]
  • Elemental sulfur can be found in or near hot springs and volcanic regions in many parts of the world; sulfur minerals are widespread, usually as sulfides or oxygen-sulfur sulfates.[254]
  • Selenium occurs in metal sulfide ores, where it partially replaces the sulfur;[255] elemental selenium is occasionally found.

Metalloids

The metalloids tend to be found in forms combined with oxygen or sulfur or, in the case of tellurium, gold or silver.[249] 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.[256]

Extraction

Nonmetals, and metalloids, are extracted in their raw forms from:[158]

  • 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).

Cost

As at January 2022, while non-radioactive nonmetals are relatively inexpensive[n 28] there are some exceptions. Boron, germanium, arsenic, and bromine can cost from about US$3 to $11 per gram (cf. silver at about $0.75 per gram). Prices can fall dramatically if bulk quantities are involved.[257] 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 per gram (ca. fifteen times the cost of gold); in contrast, red phosphorus costs about 50 cents a gram or $227 a pound.[258] 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 ca. $86,000,000 per gram, with no indication of a discount for bulk quantities).[259]

Shared uses

Nearly all nonmetals have varying uses in household items; lasers and lighting; and medicine and pharmaceuticals. Nitrogen, for example, is found in some garden treatments; lasers; and diabetes medicines. Germanium, arsenic, and radon each have uses in one or two of these fields but not all three.[158] Aside from the noble gases most of the remaining nonmetals have, or have had, uses in agrochemicals and dyestuffs.[158] To the extent that metalloids show metallic character, they have speciality uses extending to (for example) oxide glasses, alloying components, and semiconductors.[260]

Further shared uses of different subsets of the nonmetals encompass their presence in, or specific uses in the fields of air replacements; cryogenics and refrigerants; fertilizers; flame retardants or fire extinguishers; mineral acids; plug-in hybrid vehicles; welding gases; and smart phones.[158]

Discovery

a man kneels in one corner of a darkened room, before a glowing flask; some assistants are further behind him and discernible in the dark
The Alchemist Discovering Phosphorus (1771) by Joseph Wright. The alchemist is Hennig Brand; the glow emanates from the combustion of phosphorus inside the flask.

The majority of nonmetals were discovered in the 18th and 19th centuries. Before then carbon, sulfur and antimony were known in antiquity; arsenic was discovered during the Middle Ages (by Albertus Magnus); and Hennig Brand isolated phosphorus from urine in 1669. Helium (1868) holds the distinction of being the first (and so far only) element not discovered on Earth[n 29] while radon was the most recently discovered nonmetal, being discovered only at the end of the 19th century.[158]

Chemistry- or physics-based techniques used in the isolation efforts were spectroscopy, fractional distillation, radiation detection, electrolysis, ore acidification, combustion, displacement reactions, and heating, while a few nonmetals occurred naturally as free elements:

  • 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 radon was first observed emanating from compounds of thorium, three years after Henri Becquerel's discovery of radiation in 1896.[262]
  • The nonmetal halogens were obtained from their halides via electrolysis, adding an acid, or displacement. Some chemists died as a result of their experiments trying to isolate fluorine.[263]
  • Among unclassified nonmetals, carbon was known (or produced) as charcoal, soot, graphite and diamond; 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;[264] sulfur occurred naturally as a free element; and selenium[n 30] was detected as a residue in sulfuric acid.[266]
  • Most of the elements commonly recognized as metalloids were isolated by heating their oxides (boron, silicon, arsenic, tellurium) or a sulfide (germanium).[158] Antimony was known in its native form as well as being isolable by heating its sulfide.[267]

See also

Notes

  1. ^ Hydrogen has historically been placed over one or more of lithium, boron,[3] carbon, or fluorine[4]; or over no group at all; or over all main groups simultaneously, and therefore may or may not be adjacent to other nonmetals.[5]
  2. ^ Exceptions are carbon as graphite, which is a good conductor of electricity along its planes; carbon in its less stable diamantine form, which is an excellent conductor of heat (and which explains why diamonds are cool to the touch); and arsenic and antimony, which are sometimes regarded as nonmetals and which are good conductors of electricity
  3. ^ With nitric acid, gallium and bismuth form nitrates
  4. ^ A.The maximum possible packing efficiency is 74% (see Kepler conjecture). B. The packing efficiency of Br (15%) is determined by dividing the volume of one mole of atoms by the applicable molar volume. 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. The volume of one bromine atom is . The bond distance in solid bromine is 2.2836 Å and 2.27±0.10 Å in the gas, giving an atomic radius r of ca. 1.14 Å.[62] C. In comparison, mercury has a packing efficiency of 58.5%.[63]
  5. ^ The seven nonmetals marked with single or double daggers each have a lackluster appearance and discrete molecular structures, but for I which has a metallic appearance under white light. The remaining reactive nonmetallic elements have giant covalent structures, but for H which is a diatomic gas.[89]

    The single dagger nonmetals N, S and iodine are somewhat hobbled as "strong" nonmetals.


    While N has a high electronegativity, it is a reluctant anion former,[90] and a pedestrian oxidizing agent unless combined with a more active non-metal like O or F.[91]


    S reacts in the cold with alkalic and post-transition metals, and Cu, Ag and Hg,[92] 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.[93]
    Iodine is sufficiently corrosive to cause lesions resembling thermal burns, if handled without suitable protection,[94] and tincture of iodine will smoothly dissolve Au.[95] 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."[96] 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.[97] Thus F2, Cl2 and Br2 will oxidize Fe2+ to Fe3+ but Fe3+ will oxidize I to I2. Iodine has previously been referred to as a moderately strong oxidizing agent.[98]
  6. ^ The quote marks are not found in the source; they are used here to make it clear that the source employs the word «nonmetals» as a formal term for the subset of chemical elements in question, rather than applying to nonmetals generally.
  7. ^ 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.[117] 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".
  8. ^ Jones[121] takes a philosophical or pragmatic view to these questions. 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".
  9. ^ Metal oxides are usually ionic.[136] On the other hand, high valence oxides of metals are usually either polymeric or covalent.[137] A polymeric oxide has a linked structure composed of multiple repeating units.[138]
  10. ^ 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.[144]
  11. ^ 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.[150]
  12. ^ Greenwood[167] 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 ..."
  13. ^ The BH3 and Fe(CO4) species in these reactions are short-lived reaction intermediates.[169]
  14. ^ See also Properties of metals, metalloids and nonmetals, which treats metalloids as a class of their own
  15. ^ Carbon as exfoliated (expanded) graphite,[182] and as meter-long carbon nanotube wire;[183] phosphorus as white phosphorus (soft as wax, pliable and can be cut with a knife, at room temperature);[184] sulfur as plastic sulfur;[185] and selenium as selenium wires[186]
  16. ^ Metals have electrical conductivity values of from 6.9×103 S•cm−1 for manganese to 6.3×105 for silver.[188]
  17. ^ Metalloids have electrical conductivity values of from 1.5×10−6 S•cm−1 for boron to 3.9×104 for arsenic.[189]
  18. ^ Unclassified nonmetals have electrical conductivity values of from ca. 1×10−18 S•cm−1 for the elemental gases to 3±4 in graphite.[190]
  19. ^ The nonmetal halogens have electrical conductivity values of from ca. 1×10−18 S•cm−1 for F and Cl to 1.7×10−8 S•cm−1 for iodine.[190][191]
  20. ^ The elemental gases have electrical conductivity values of ca. 1×10−18 S•cm−1[190]
  21. ^ They always give compounds less acidic in character than the corresponding compounds of the typical nonmetals[195]
  22. ^ Values for the noble gases are from Allen and Huheey.[200]
  23. ^ 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.[205]
  24. ^ Arsenic trioxide reacts with sulfur trioxide, forming arsenic "sulfate" As2(SO4)3[212]
  25. ^ CO and N2O are "formally the anhydrides of formic and hyponitrous acid, respectively: CO + H2O → H2CO2 (HCOOH, formic acid); N2O + H2O → H2N2O2 (hyponitrous acid)".[216]
  26. ^ B; Si, Ge; N, P; O, S, Se, Te; nonmetal halogens; and the noble gases[192]
  27. ^ As at 2020, high pressure studies and experiments were said to represent, "a very active and vigorous research field".[238]
  28. ^ Costs for most nonmetals ranged from US$0.0002 per gram for bulk oxygen to $1.90 per gram for bulk fluorine.[257]
  29. ^ 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".[261]
  30. ^ Berzelius, who discovered selenium, thought it had the properties of a metal, combined with those of sulfur.[265]

References

Citations

  1. ^ Steudel 1977, passim; Powell & Tims 1974, passim; Emsley 1971, passim
  2. ^ Hampel & Hawley 1976, pp. 174, 191; Lewis 1993, p. 835; Hérold 2006, pp. 149–50
  3. ^ Luchinskii & Trifonov 1981, pp. 200–220
  4. ^ a b Jolly 1966, inside cover
  5. ^ Rayner-Canham 2020, p. 212
  6. ^ Johnson 1966, pp. 3–6, 13–15, 113
  7. ^ Johnson 1966, p. 15
  8. ^ a b c Kneen, Rogers & Simpson 1972, pp. 218–219
  9. ^ a b MacKay, MacKay & Henderson 2002, p. 200
  10. ^ a b Nelson 1987, p. 732
  11. ^ a b Brooks 1992, p. 4
  12. ^ Schulze-Makuch & Irwin 2008, p. 89.
  13. ^ Imberti 2020, passim
  14. ^ Csele 2016, passim; Winstel 2000, passim
  15. ^ Emsley 2011, pp. 39, 44, 80–81, 85, 199, 248, 263, 367, 478, 531, 610
  16. ^ Sanderson 1957, p. 229
  17. ^ Oxtoby, Gillis & Butler 2015, p. I.23
  18. ^ Mendeléeff 1897, p. 23: "It is…impossible to draw a strict line of demarcation between metals and nonmetals, there being many intermediate substances."
  19. ^ Bodner & Pardue 1993, p. 354; Cherim 1971, p. 98
  20. ^ Mewes et al. 2019; Smits et al. 2020
  21. ^ IUPAC Periodic Table of the Elements
  22. ^ Van Setten et al. 2007, pp. 2460–2461; Oganov et al. 2009, pp. 863–864
  23. ^ Hill & Holman 2000, p. 124
  24. ^ Shakhashiri, Dirreen & Williams 1989, pp. 373–374
  25. ^ Wiberg 2001, pp. 403, 472
  26. ^ Schenk & Prins 1953, p. 957
  27. ^ Deming 1923, p. 544
  28. ^ McCall et al. 2014, pp. 1380−1392
  29. ^ Lidin 1996, pp. 64‒65
  30. ^ Freemantle 1987, pp. 404, 425, 573, 593, 603
  31. ^ Jesperson, Brady & Hyslop 2012, p. 8; Johnson 1966, pp. 3–4; Cotton & Wilkinson 1976, p. 288
  32. ^ a b 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
  33. ^ Oderberg 2007, p. 97
  34. ^ Kendall 1811, pp. 298–303
  35. ^ Brande 1821, p. 5
  36. ^ Kubaschewski 1949, pp. 931–940
  37. ^ Remy 1956, p. 9
  38. ^ White 1962, p. 106
  39. ^ a b Johnson 1966, pp. 3−4
  40. ^ Horvath 1973, pp. 335–336
  41. ^ Edwards & Sienko 1983, pp. 691–96
  42. ^ Rao & Ganguly 1986
  43. ^ Smith & Dwyer 1991, p. 65
  44. ^ Herman 1999, pp. 701–748
  45. ^ Hill & Holman 2000, p. 160
  46. ^ Suresh & Koga 2001, pp. 5940−5944
  47. ^ Johnson 2007, pp. 15−16
  48. ^ a b Edwards 2010, pp. 941–965
  49. ^ Povh & Rosin 2017, p. 131
  50. ^ Beach 1911
  51. ^ Stott 1956, pp. 100–102
  52. ^ Abbott 1966, p. 18
  53. ^ Parish 1977, p. 178
  54. ^ Sanderson 1957, p. 229
  55. ^ Leach & Ewing 1966, p. 47
  56. ^ Brady & Senese 2009, p. 52
  57. ^ Zumdahl & DeCoste 2018, p. 90
  58. ^ Homberg 1798, p. 350
  59. ^ Schlager & Lauer 2000, p. 370
  60. ^ Strathern 2000, p. 239
  61. ^ Salzberg 1991, p. 204
  62. ^ Donohue 1982, p. 297
  63. ^ Okajima & Shomoji 1972, p. 258
  64. ^ Russell & Lee 2005, pp. 1‒8
  65. ^ a b c d Kneen, Rogers & Simpson 1972, pp. 261–264
  66. ^ Herzfeld 1927, pp. 701–05; Edwards 2000, pp. 100–03
  67. ^ Yoder, Suydam & Snavely 1975, p. 58
  68. ^ Abbott 1966, p. 18
  69. ^ Kneen, Rogers & Simpson 1972, pp. 263‒264
  70. ^ Brown et al. 2014, p. 237
  71. ^ Young et al. 2018, p. 753
  72. ^ Brown et al. 2014, p. 227
  73. ^ Siekierski & Burgess 2002, pp. 21, 133, 177
  74. ^ Moore 2016; Burford, Passmore & Sanders 1989, p. 54
  75. ^ King & Caldwell 1954, p. 17; Brady & Senese 2009, p. 69
  76. ^ Chemical Abstracts Service 2021
  77. ^ Cockell 2019, p. 210
  78. ^ Emsley 2011, pp. 81, 181; Scott 2016, p. 3
  79. ^ Kneen, Rogers & Simpson 1972, pp. 226, 360
  80. ^ Steudel 1977, preface
  81. ^ Lee 1996, p. 240
  82. ^ Greenwood & Earnshaw 2002, p. 43
  83. ^ Cressey 2010
  84. ^ Siekierski & Burgess 2002, pp. 24–25
  85. ^ Siekierski & Burgess 2002, p. 23
  86. ^ Greenwood & Earnshaw 2002, p. 27
  87. ^ Siekierski & Burgess 2002, pp. 52, 101, 111, 124, 194
  88. ^ Cox 2004, p. 146
  89. ^ Wiberg 2001, passim
  90. ^ Vernon 2020, p. 222
  91. ^ Atkins & Overton 2010, pp. 377, 389
  92. ^ Moody 1991, p. 391
  93. ^ Rodgers 2010, p. 504; Wulfsberg 2000, p. 726
  94. ^ Stellman 1998, chapter 104-211
  95. ^ Nakao 1992, p. 426–427
  96. ^ Hill & Holman 2000, p. 124
  97. ^ Wiberg 2001, pp. 1761–1762
  98. ^ Young 2006, p. 1285
  99. ^ Bertomeu-Sánchez, Garcia-Belmar & Bensaude-Vincent 2002, pp. 248–249
  100. ^ Dupasquier 1844, pp. 66–67
  101. ^ Berzelius 1832, pp. 248–276
  102. ^ The Chemical News 1864, p. 22
  103. ^ Williams 2007, pp. 1550–1561
  104. ^ Wächtershäuser 2014
  105. ^ Hengeveld & Fedonkin, pp. 181–226
  106. ^ Wakeman 1899, p. 562
  107. ^ Fraps 1913, p. 11
  108. ^ Parameswaran at al. 2020, p. 210
  109. ^ Knight 2002, p. 148
  110. ^ Fraústo da Silva & Williams 2001, p. 500
  111. ^ Renouf 1901, pp. 268
  112. ^ Encyclopaedia Britannica 2021
  113. ^ Royal Society of Chemistry 2021
  114. ^ Chambers & Holliday 1982, pp. 273–274; Bohlmann 1992, p. 213; Jentzsch 2015, p. 247
  115. ^ Vassilakis, Kalemos & Mavridis 2014, p. 1; Hanley & Koga 2018, p. 24; Kaiho 2017, ch. 2, p. 1
  116. ^ Bailar et al. 1989, p. 742
  117. ^ Tshitoyan et al. 2019, pp. 95-98
  118. ^ Hampel & Hawley 1976, p. 174;
  119. ^ Goodrich 1844, p. 264; The Chemical News 1897, p. 189; Hampel & Hawley 1976, p. 191; Lewis 1993, p. 835; Hérold 2006, pp. 149–50
  120. ^ Tyler 1948, p. 105; Reilly 2002, pp. 5–6
  121. ^ Jones 2010, pp. 169–71
  122. ^ Stein 1983, p. 165
  123. ^ Matson & Orbaek 2013, p. 203
  124. ^ Jolly 1966, p. 20
  125. ^ Clugston & Flemming 2000, pp. 100–101, 104–105, 302
  126. ^ Maosheng 2020, p. 962
  127. ^ Mazej 2020
  128. ^ Wiberg 2001, p. 1131
  129. ^ Vernon 2020, p. 229
  130. ^ Rayner-Canham 2020, p. 92, 139
  131. ^ a b c d e Vernon 2013, pp. 1703‒1707
  132. ^ Greenwood & Earnshaw 2002, p. 804
  133. ^ Rudolph 1973, p. 133: "Oxygen and the halogens in particular...are therefore strong oxidizing agents."
  134. ^ Daniel & Rapp 1976, p. 55
  135. ^ a b Cotton et al. 1999, p. 554
  136. ^ Woodward et al. 1999, pp. 133–194
  137. ^ Phillips & Williams 1965, pp. 478–479
  138. ^ Moeller et al. 2012, p. 314
  139. ^ Lanford 1959, p. 176
  140. ^ Massey 2000, p. 113
  141. ^ Greenwood & Earnshaw 2002, p. 277
  142. ^ Atkins et al. 2006, p. 320
  143. ^ Greenwood & Earnshaw 2002, p. 482; Berger 1997, p. 86
  144. ^ Moss 1952, pp. 180, 202
  145. ^ a b Vernon 2020, pp. 221–223
  146. ^ a b c d e Cao et al. 2021, pp. 20–21
  147. ^ Challoner 2014, p. 5; Government of Canada 2015; Gargaud et al. 2006, p. 447
  148. ^ Crichton 2012, p. 6; Scerri 2013; Los Alamos National Laboratory 2021
  149. ^ Vernon 2020, p. 218
  150. ^ Wulfsberg 2000, pp. 273–274, 620
  151. ^ Seese & Daub 1985, p. 65
  152. ^ MacKay, MacKay & Henderson 2002, p. 209
  153. ^ Cousins, Davidson & García-Vivó 2013, pp. 11809–11811
  154. ^ a b Wiberg 2001, pp. 255–257
  155. ^ Liptrot 1983, p. 161
  156. ^ Scott & Kanda 1962, p. 153
  157. ^ Taylor 1960, p. 316
  158. ^ a b c d e f g Emsley 2011, passim
  159. ^ Crawford 1968, p. 540
  160. ^ 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."
  161. ^ Zumdahl & Zumdahl 2009, p. 925
  162. ^ Messler 2011, p. 10
  163. ^ King et al. 1994, p. 1344; Powell & Tims 1974, pp. 189–191
  164. ^ Rayner-Canham 2020, p. 216
  165. ^ Atkins 2001, pp. 24–25
  166. ^ MacKay, MacKay & Henderson 2002, p. 436
  167. ^ Greenwood 2001, p. 2057
  168. ^ Houghton 1979, p. 59
  169. ^ Fehlner 1990, p. 205
  170. ^ Fehlner 1990, pp. 204–05, 207
  171. ^ Masterton, Hurley & Neth 2011, p. 38
  172. ^ McCue 1963, p. 264
  173. ^ Dingle 2017, p. 101
  174. ^ Tregarthen 2003, p. 10
  175. ^ a b Rochow 1966, passim
  176. ^ Wiberg 2001, p. 780; Emsley 2011, p. 397; Rochow 1966, pp. 23, 84
  177. ^ Kneen, Rogers & Simpson 1972, pp. 321, 404, 436
  178. ^ Kneen, Rogers & Simpson 1972, p. 439
  179. ^ Kneen, Rogers & Simpson 1972, p. 465
  180. ^ Kneen, Rogers & Simpson 1972, p. 308
  181. ^ Wiberg 2001, pp. 505, 681, 781; Glinka 1965, p. 356
  182. ^ Chung 1987, pp. 4190‒4198; Godfrin & Lauter 1995, pp.  216‒218
  183. ^ Cambridge Enterprise 2013
  184. ^ Faraday 1853, p. 42; Holderness & Berry 1979, p. 255
  185. ^ Partington 1944, p. 405
  186. ^ Regnault 1853, p. 208
  187. ^ Wiberg 2001, p. 416
  188. ^ Desai, James & Ho 1984, p. 1160; Matula 1979, p. 1260
  189. ^ Schaefer 1968, p. 76; Carapella 1968, pp. 29‒32
  190. ^ a b c Bogoroditskii & Pasynkov 1967, p. 77; Jenkins & Kawamura 1976, p. 88
  191. ^ Greenwood & Earnshaw 2002, p. 804
  192. ^ a b Keeler & Wothers 2013, p. 293
  193. ^ Kneen, Rogers & Simpson 1972, p. 264
  194. ^ Rayner-Canham 2018, p. 203
  195. ^ a b Rochow 1966, p. 4
  196. ^ Welcher 2001, p. 3-32: "The elements change from...metalloids, to moderately active nonmetals, to very active nonmetals, and to a noble gas."
  197. ^ Mackin 2014, p. 80
  198. ^ Johnson 1966, pp. 105–108
  199. ^ Stein 1969, pp. 5396‒5397; Pitzer 1975, pp. 760‒761
  200. ^ Allen & Huheey 1980, pp. 1523–1524
  201. ^ Yamaguchi & Shirai 1996, p. 3
  202. ^ Vernon 2020, p. 223
  203. ^ Vernon 2020, p. 220
  204. ^ Woodward et al. 1999, p. 134
  205. ^ Dalton 2019
  206. ^ Wells 1984, p. 534
  207. ^ a b Rao 2002, p. 22
  208. ^ Porterfield 1993, p. 336
  209. ^ a b c d Puddephatt & Monaghan 1989, p. 59
  210. ^ Sidorov 1960, pp. 599‒603
  211. ^ Atkins et al. 2006, pp. 8, 122–123
  212. ^ Wiberg 2001, p. 750
  213. ^ McMillan 2006, p. 823
  214. ^ a b Sanderson 1967, p. 172
  215. ^ a b Mingos 2019, p. 27
  216. ^ House 2008, p. 441
  217. ^ King 1995, p. 182
  218. ^ Ritter 2011, p. 10
  219. ^ Wiberg 2001, p. 399
  220. ^ Kläning & Appelman 1988, p. 3760
  221. ^ Steudel 1977, p. 176
  222. ^ Vernon 2020, pp. 217–225
  223. ^ Barton 2021, p. 200
  224. ^ Shanabrook, Lannin & Hisatsune 1981, pp. 130‒133
  225. ^ Borg & Dienes 1992, p. 26
  226. ^ Wiberg 2001, p. 796
  227. ^ Cacace, de Petris & Troiani 2002, pp. 480‒481
  228. ^ Koziel 2002, p. 18
  229. ^ Gusmão, Sofer & Pumera 2017, p. 8052–8053; Berger 1997, p. 84; Vernon 2013, pp. 1704‒1705
  230. ^ Piro et al. 2006, pp. 1276‒1279
  231. ^ Steudel & Eckert 2003, p. 1
  232. ^ Greenwood & Earnshaw 2002, pp. 659–660
  233. ^ Moss 1952, p. 192; Greenwood & Earnshaw 2002, p. 751
  234. ^ Shiell at al. 2021
  235. ^ Zhao et al. 2017
  236. ^ Brodsky et al. 1972, p. 609–614
  237. ^ Yousuf 1998, p. 425; Elatresh & Bonev 2020
  238. ^ Errandonea 2020, p. 595
  239. ^ Su et al. 2020, pp. 1621–1649
  240. ^ Cox 1997, pp. 17, 19
  241. ^ Ostriker & Steinhardt 2001, pp. 46‒53
  242. ^ Peterson & Depaolo 2007; Williams 2014
  243. ^ Cox 2000, pp. 258–259; Möller 2003, p. 173; Trenberth & Smith 2005, p. 864
  244. ^ Emsley 2011, p. 220
  245. ^ Emsley 2011, p. 440
  246. ^ Zhu et al. 2014, pp. 644–648
  247. ^ Schmedt, Mangstl & Kraus 2012, p. 7847‒7849
  248. ^ Emsley 2011, p. 117
  249. ^ a b Cox 1997, pp. 130–132; Emsley 2011, passim
  250. ^ National Center for Biotechnology Information 2021
  251. ^ Emsley 2011, p. 113
  252. ^ Greenwood & Earnshaw 2002, p. 270–271
  253. ^ Cox 1997, pp. 130; Emsley 2011, p. 393
  254. ^ Cox 1997, pp. 130; Emsley 2011, pp. 515–516, 518
  255. ^ Boyd 2011, p. 570
  256. ^ Hurlbut 1961, p. 132
  257. ^ a b Stewart n.d.
  258. ^ Boise State University 2020
  259. ^ National Institute of Standards and Technology 2013
  260. ^ Gaffney & Marley 2017, p. 27
  261. ^ Labinger 2019, p. 305
  262. ^ Emsley 2011, pp. 42–43, 219–220, 263–264, 341, 441–442, 596, 609
  263. ^ Emsley 2011, pp. 84, 128, 180–181, 247
  264. ^ Cook 1923, p. 124
  265. ^ Weeks 1945, p. 161
  266. ^ Emsley 2011, pp. 113, 363, 378, 477, 514–515
  267. ^ Weeks 1945, p. 22; Emsley 2011, p. 40

Bibliography

  • Abbott D 1966, An Introduction to the Periodic Table, J. M. Dent & Sons, 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
  • Atkins PA 2001, The Periodic Kingdom: A Journey Into the Land of the Chemical Elements, Phoenix, London, ISBN 978-1-85799-449-0
  • Atkins PA et al. 2006, Shriver & Atkins' Inorganic Chemistry, 4th ed., Oxford University Press, Oxford, ISBN 978-0-7167-4878-6
  • Atkins PA & Overton T 2010, Shriver & Atkins' Inorganic Chemistry, 5th ed., Oxford University Press, Oxford, ISBN 978-0-19-923617-6
  • Aylward G and Findlay T 2008, SI Chemical Data, 6th ed., John Wiley & Sons Australia, Milton, ISBN 978-0-470-81638-7
  • Bailar JC et al. 1989, Chemistry, 3rd ed., Harcourt Brace Jovanovich, San Diego, ISBN 978-0-15-506456-0
  • 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
  • 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
  • Bertomeu-Sánchez JR, Garcia-Belmar A & Bensaude-Vincent B 2002, "Looking for an order of things: Textbooks and chemical classifications in nineteenth century France", Ambix, vol. 49, no. 3, doi:10.1179/amb.2002.49.3.227
  • 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
  • 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
  • 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
  • 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
  • Brooks RR 1992, Noble metals and biological systems: Their role in medicine, mineral exploration, and the environment, Routledge, Boca Raton, ISBN 978-0-8493-6164-7
  • Brown TL et al. 2014, Chemistry: The Central Science, 3rd ed., Pearson Australia: Sydney, ISBN 978-1-4425-5460-3
  • 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 C et al. 2021, "Understanding periodic and non-periodic chemistry in periodic tables", Frontiers in Chemistry, vol. 8, no. 813, doi:10.3389/fchem.2020.00813
  • Carapella SC 1968, "Arsenic" in Hampel CA (ed.), The Encyclopedia of the Chemical Elements, Reinhold, New York
  • 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
  • Chemical Abstracts Service 2021, CAS REGISTRY database as of November 2nd, Case #01271182
  • 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
  • Cook CG 1923, Chemistry in Everyday Life: With Laboratory Manual, D Appleton, New York
  • Cotton A 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, 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 D 2010, "Chemists re-define hydrogen bond", Nature newsblog, accessed August 23, 2017
  • Csele M 2016, Lasers, in Ullmann's Encyclopedia of Industrial Chemistry, doi:10.1002/14356007.a15_165.pub2
  • 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
  • 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
  • Dingle 2017, The Elements: An Encyclopedic Tour of the Periodic Table, Quad Books, Brighton, ISBN 978-0-85762-505-2
  • 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.
  • 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:10.1021/ed060p691, PMID 25666074
  • 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
  • Emsley J 1971, The Inorganic Chemistry of the Non-metals, Methuen Educational, London, ISBN 978-0-423-86120-4
  • 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, 2021
  • 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
  • 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
  • Freemantle MH 1987, Chemistry in Action, 2nd ed., Macmillan, Basingstoke, Hampshire ISBN 978-0-333-37310-1
  • Gaffney J & Marley N 2017, General Chemistry for Engineers, Elsevier, Amsterdam, ISBN 978-0-12-810444-6
  • Gargaud M 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, Sobolev D (trans.), 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
  • 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
  • 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
  • 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
  • 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
  • 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 G & Holman J 2000, Chemistry in Context, 5th ed., Nelson Thornes, Cheltenham, ISBN 978-0-17-448307-6
  • Holderness A & Berry M 1979, Advanced Level Inorganic Chemistry, 3rd ed., Heinemann Educational Books, London, ISBN 978-0-435-65435-1
  • Homberg W 1708, "Des Essais de Chimie", in Histoire De L'Academie Royale Des Sciences: Avec les Memoires de Mathematique & de Physique, L'Académie, Paris
  • 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
  • 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 11, 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
  • Jørgensen SE & Mitsch WJ (eds.) 1983, Application of ecological modelling in environmental management, part A, Elsevier Science Publishing, Amsterdam, ISBN 978-0-444-41948-4
  • 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
  • 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
  • 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
  • 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
  • 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
  • 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
  • Massey AG 2000, Main group chemistry, 2nd ed., John Wiley & Sons, Chichester, ISBN 978-0-471-49039-5
  • 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 AS 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
  • McMillan P 2006, "A glass of carbon dioxide", Nature, vol. 441, doi:10.1038/441823a
  • Mendeléeff DI 1897, The principles of chemistry, vol. 1, 5th ed., Kamensky G (trans.), Greenaway AJ (ed.), Longmans, Green & Co., London
  • 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: A relativistic noble liquid, Angewandte Chemie International Edition, vol. 58, pp. 17964–17968, doi:10.1002/anie.201906966
  • 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
  • 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
  • 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, accessed August 1, 2021
  • Nelson PG 1987, "Important elements", Journal of Chemical Education, vol. 68, no. 9, doi:10.1021/ed068p732
  • Oderberg DS 2007, Real Essentialism, Routledge, New York, ISBN 978-1-134-34885-5
  • Oganov AR 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
  • Oxtoby DW, Gillis HP & Butler LJ 2015, Principles of Modern Chemistry, 8th ed., Cengage Learning, Boston, ISBN 978-1-305-07911-3
  • Parameswaran P 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
  • Peterson BT & Depaolo DJ 2007, Mass and composition of the continental crust estimated using the CRUST2.0 model, American Geophysical Union, Fall Meeting 2007, abstract id. V33A-1161, accessed November 28, 2021
  • Phillips CSG & Williams RJP 1965, Inorganic Chemistry, vol. 1, Principles and non-metals, Clarendon Press, Oxford
  • Piro NA et al. 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
  • Powell P & Timms P 1974, The Chemistry of the Non-Metals, Chapman and Hall, London, ISBN 978-0-412-12200-2
  • Puddephatt RJ & Monaghan PK 1989, The Periodic Table of the Elements, 2nd ed., Clarendon Press, Oxford, ISBN 978-0-19-855516-2
  • 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, pp. 5–6, doi:10.1016/0038-1098(86)90659-9
  • 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 2020, The Periodic Table: Past, Present and Future, World Scientific, New Jersey, ISBN 978-981-121-850-7
  • 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
  • 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
  • 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 JC 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
  • 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 1973, Chemistry for the Modern Mind, Macmillan, New York
  • Russell AM & Lee KL 2005, Structure-Property Relations in Nonferrous Metals, Wiley-Interscience, New York, ISBN 0-471-64952-X
  • Salzberg HW 1991, From Caveman to Chemist: Circumstances and Achievements, American Chemical Society, Washington DC, ISBN 0-8412-1786-6
  • 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
  • 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
  • Schlager N & Lauer J (eds.) 2000, Science and Its Times: 1700-1799, volume 4 of Science and its times: Understanding the social significance of scientific discovery, Gale Group, ISBN 978-0-7876-3932-7
  • 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
  • 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
  • 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
  • Siekierski S & Burgess J 2002, Concise Chemistry of the Elements, Horwood Press, Chichester, ISBN 978-1-898563-71-6
  • 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
  • Smits et al. 2020, Oganesson: A noble gas element that is neither noble nor a gas, Angewandte Chemie International Edition, vol. 59, pp. 23636–23640, doi:10.1002/anie.202011976
  • 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.1983.32.13.163
  • 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
  • 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
  • Strathern P 2000, Mendeleyev's dream: The Quest for the Elements, Hamish Hamilton, London, ISBN 978-0-8412-1786-7
  • 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
  • Taylor MD 1960, First Principles of Chemistry, Van Nostrand, Princeton
  • The Chemical News and Journal of Physical Science 1864, "Notices of books: Manual of the Metalloids", vol. 9, p. 22
  • The Chemical News and Journal of Physical Science 1897, "Notices of books: A Manual of Chemistry, Theoretical and Practical", by WA Tilden", vol. 75, pp. 188–189
  • 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, 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
  • 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
  • Wakeman TH 1899, "Free thought—Past, present and future", Free Thought Magazine, vol. 17
  • Weeks ME 1945, 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
  • Williams M 2014, "What percent of Earth is water?", Universe Today, accessed December 17, 2021
  • 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
  • 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 structures", 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
  • Young et al. 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, article no. 13909, 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
  • 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

External links

  • Media related to Nonmetals at Wikimedia Commons