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Nonmetals in their periodic table context
  usually/always counted as a nonmetal
  sometimes counted as a nonmetal
At Astatine's status is unclear; while usually counted as a nonmetal, relativistic effects suggest it may be a metal.[1]
Cn Fl Og Copernicium, flerovium, and/or oganesson may turn out to be nonmetallic, however their status has not been confirmed.

A nonmetal is a chemical element that mostly lacks metallic properties. Seventeen elements are generally considered nonmetals, though some authors recognize more or fewer depending on the properties considered most representative of metallic or nonmetallic character. Some borderline elements further complicate the situation.

Nonmetals tend to have low density and high electronegativity (the ability of an atom in a molecule to attract electrons to itself). They range from colorless gases like hydrogen to shiny solids like the graphite form of carbon. Nonmetals are often poor conductors of heat and electricity, and when solid tend to be brittle or crumbly. In contrast, metals are good conductors and most are pliable. While oxides of metals tend to be basic, those of nonmetals tend to be acidic.

The two lightest nonmetals, hydrogen and helium, together make up about 98% of the observable ordinary matter in the universe by mass. Five nonmetallic elements—hydrogen, carbon, nitrogen, oxygen, and silicon—make up the overwhelming majority of the Earth's crust, atmosphere, oceans and biosphere.[n 1]

The distinct properties of nonmetallic elements allow for specific uses that metals often cannot achieve. Elements like hydrogen, oxygen, carbon, and nitrogen are essential building blocks for life itself. Moreover, nonmetallic elements are integral to industries such as electronics, energy storage, agriculture, and chemical production.

Most nonmetallic elements were not identified until the 18th and 19th centuries. While a distinction between metals and other minerals had existed since antiquity, a basic classification of chemical elements as metallic or nonmetallic emerged only in the late 18th century. Since then nigh on two dozen properties have been suggested as single criteria for distinguishing nonmetals from metals.

Definition and applicable elements[edit]

Properties mentioned hereafter refer to the elements in their most stable forms in ambient conditions unless otherwise mentioned
Two dull silver clusters of crystalline shards.
Like carbon, arsenic (here sealed in a container to prevent tarnishing) vaporises rather than melts when heated. The vapor is lemon-yellow and smells like garlic.[2] The chemistry of arsenic is predominately nonmetallic in nature.[3]

Nonmetal chemical element generally have low density and high electronegativity. They lack most or all of the properties commonly associated with metals: shininess; malleability and ductility; good thermal and electrical conductivity; and a capacity to (mostly) produce basic oxides when combined with oxygen.[4][n 2]

There is no precise definition of a nonmetal;[6] any list of such is open to debate and revision.[7] Which elements are included depends on the properties regarded as most representative of nonmetallic or metallic character.[n 3]

These fourteen elements are effectively always recognized as nonmetals:[7][8]

Three more are commonly called nonmetals, but some sources list them as metalloids:[9]

The six elements most commonly recognized as metalloids, which are typically seen as intermediates between metals and nonmetals, are here counted as a type of nonmetal due to their relatively low densities and predominantly nonmetallic chemistry, and for comparative purposes:[10]

Of the 118 known elements,[11] roughly 20% are classified as nonmetals.[12] Opinions differ as to the status of astatine. Its rarity and extreme radioactivity has resulted in it being frequently ignored in the literature.[13] With no comprehensive understanding of its properties, its classification remains uncertain. As a halogen it has usually been presumed to be a nonmetal.[14] Chemically, studies on trace quantities of astatine, which are not necessarily reliable,[15] have demonstrated characteristics of both metals and nonmetals.[16] Alternatively, given the near-metallic character of its lighter congener iodine,[n 4] a succession of authors suggest astatine may be a metal.[18] A 2013 study based on relativistic chemistry concluded that it would be a monatomic metal with a close-packed crystalline structure,[19] but this has not been experimentally verified. Astatine is not considered further in this article due to uncertainty as to its behavior and status. The superheavy elements copernicium (element 112), flerovium (114), and oganesson (118) may or may not turn out to be nonmetals; their status has not been confirmed.[20]

General properties[edit]


Variety in color and form
of some nonmetallic elements
Several dozen small angular stone like shapes, grey with scattered silver flecks and highlights.
Boron in its β-rhombohedral phase
A shiny grey-black cuboid nugget with a rough surface.
Metallic appearance of carbon as graphite
A pale blue liquid in a clear beaker
Blue color of liquid oxygen
A glass tube, is inside a larger glass tube, has some clear yellow liquid in it
Pale yellow liquid fluorine in a cryogenic bath
Yellow powdery chunks
Sulfur as a yellow powder
A small capped jar a quarter filled with a very dark liquid
Liquid bromine at room temperature
Shiny violet-black colored crystalline shards.
Metallic appearance of iodine under white light
A partly filled ampoule containing a colorless liquid
Liquefied xenon

About half of nonmetallic elements are gases; most of the rest are shiny solids. Bromine, the only liquid, is so volatile that it is usually topped by a layer of its fumes; sulfur is the only colored solid nonmetal.[n 5] The gaseous and liquid nonmetals have very low densities, melting and boiling points, and are poor conductors of heat and electricity.[23] The solid elements have low densities and low mechanical and structural strength (being brittle or crumbly),[24] but a wide range of electrical conductivity.[n 6]

These diverse forms are caused by varied internal structures and bonding arrangements. Nonmetals existing as discrete atoms like xenon, or as small molecules, such as oxygen, sulfur, and bromine, have low melting and boiling points; many are gases at room temperature, as they are held together by weak London dispersion forces acting between their atoms or molecules.[28] In contrast, nonmetals that form giant structures, such as chains of up to 1,000 atoms (e.g., selenium),[29] sheets (e.g., carbon as graphite),[30] or three-dimensional lattices (e.g., silicon)[31] have higher melting and boiling points, and are all solids, as it takes more energy to overcome their stronger covalent bonds.[32] Nonmetals closer to the left or bottom of the periodic table, often have some weak metallic interactions between their molecules, chains, or layers, consistent with their proximity to the metals; this occurs in boron,[33] carbon,[34] phosphorus,[35] arsenic,[36] selenium,[37] antimony,[38] tellurium[39] and iodine.[40]

The structures of nonmetallic elements differ from those of metals primarily due to variations in valence electrons and atomic size. Metals typically have fewer valence electrons than available orbitals, leading them to share electrons with many nearby atoms, resulting in centrosymmetrical crystalline structures.[41] In contrast, nonmetals share only the electrons required to achieve a noble gas electron configuration.[42] For example, nitrogen forms diatomic molecules featuring a triple bonds between each atom, both of which thereby attain the configuration of the noble gas neon; while antimony's larger atomic size prevents triple bonding, resulting in buckled layers in which each antimony atom is singly bonded with three other nearby atoms.[43]

Nonmetals vary greatly in appearance. The shininess of boron, graphitic carbon, silicon, black phosphorus, germanium, arsenic, selenium, antimony, tellurium, and iodine is a result of their structures featuring varying degrees of delocalized (free-moving) electrons that scatter incoming visible light.[44] The colored nonmetals (sulfur, fluorine, chlorine, bromine) absorb some colors (wavelengths) and transmit the complementary or opposite colors. For example, chlorine’s "familiar yellow-green colour ... is due to a broad region of absorption in the violet and blue regions of the spectrum".[45][n 7] For the colorless nonmetals (hydrogen, nitrogen, oxygen, and the noble gases), their electrons are held sufficiently strongly so that no absorption happens in the visible part of the spectrum, and all visible light is transmitted.[47]

The electrical and thermal conductivities of nonmetals, along with the brittle nature of solid nonmetals are likewise related to their internal arrangements. Whereas good conductivity and plasticity (malleability, ductility) are ordinarily associated with the presence of free-moving and evenly distributed electrons in metals,[48] the electrons in nonmetals typically lack such mobility.[49] Among nonmetallic elements, good electrical and thermal conductivity is seen only in carbon (as graphite, along its planes), arsenic, and antimony.[n 8] Good thermal conductivity otherwise occurs only in boron, silicon, phosphorus, and germanium;[25] such conductivity is transmitted though vibrations of the crystalline lattices of these elements.[50] Moderate electrical conductivity is observed in boron, silicon, phosphorus, germanium, selenium, tellurium, and iodine.[n 9] Plasticity occurs under limited circumstances in carbon, as seen in exfoliated (expanded) graphite[52][53] and carbon nanotube wire,[54] in white phosphorus (soft as wax, pliable and can be cut with a knife, at room temperature),[55] in plastic sulfur,[56] and in selenium which can be drawn into wires from its molten state.[57]

The physical differences between metals and nonmetals arise from internal and external atomic forces. Internally, the positive charge stemming from the protons in an atom's nucleus acts to hold the atom's outer electrons in place. Externally, the same electrons are subject to attractive forces from protons in neighboring atoms. When the external forces are greater than, or equal to, the internal force, the outer electrons are expected to become relatively free to move between atoms, and metallic properties are predicted. Otherwise nonmetallic properties are expected.[58]


a haphazard aggregate of brownish crystals
Brownish crystals of buckminsterfullerene60), a semiconducting allotrope of carbon
Some chemistry-based typical
differences between metals and nonmetals[59]
Aspect Metals Nonmetals
Electronegativity Lower than nonmetals,
with some exceptions[60]
Relatively high
Seldom form
covalent bonds
Frequently form
covalent bonds
Metallic bonds (alloys)
between metals
Covalent bonds
between nonmetals
Ionic bonds between nonmetals and metals
Positive Negative or positive
Oxides Basic in lower oxides;
increasingly acidic
in higher oxides
never basic[61]
In aqueous
Exist as cations Exist as anions
or oxyanions

Many nonmetallic elements exhibit a range of allotropic forms, each with distinct physical properties that may vary between metallic and nonmetallic.[63] For example, carbon, a versatile nonmetal, can manifest as graphite, diamond, and other forms, with graphite displaying relatively good electrical conductivity, while diamond is transparent and an extremely poor conductor of electricity.[64] Carbon further exists in several allotropic structures, including buckminsterfullerene,[65] and amorphous[66] and paracrystalline (mixed amorphous and crystalline)[67] variations. Allotropes also occur for the other unclassified nonmetals, the metalloids, and iodine among the halogen nonmetals.[68]


Nonmetals have relatively high values of electronegativity, and their oxides are therefore usually acidic. Exceptions occur when the oxidation state is low, the nonmetal is not very electronegative, or both: thus, water (H2O) is amphoteric[69] and nitrous oxide (N2O) is neutral.[70][n 10]

They tend to gain or share electrons during chemical reactions, in contrast to metals which tend to donate electrons. This behavior is closely related to the stability of electron configurations in the noble gases, which have complete outer shells. Nonmetals generally gain enough electrons to attain the electron configuration of the following noble gas, while metals tend to lose electrons, achieving the electron configuration of the preceding noble gas. These tendencies in nonmetallic elements are succinctly summarized by the duet and octet rules of thumb.

Furthermore, nonmetals typically exhibit higher ionization energies, electron affinities, and standard reduction potentials than metals. Generally, the higher these values are (including electronegativity) the more nonmetallic the element tends to be.[73] For example, the chemically very active nonmetals fluorine, chlorine, bromine, and iodine have an average electronegativity of 3.19—a figure[n 11] higher than that of any individual metal. On the other hand, the 2.05 average[n 12] of the chemically weak metalloid nonmetals falls within the 0.70 to 2.54 range of metals.[74]

The chemical distinctions between metals and nonmetals primarily stem from the attractive force between the positive nuclear charge of an individual atom and its negatively charged outer electrons. From left to right across each period of the periodic table, the nuclear charge increases in tandem with the number of protons in the atomic nucleus.[75] Consequently, there is a corresponding reduction in atomic radius[76] as the heightened nuclear charge draws the outer electrons closer to the nucleus core.[77] In metals, the impact of the nuclear charge is generally weaker compared to nonmetallic elements. As a result, in chemical bonding, metals tend to lose electrons, leading to the formation of positively charged or polarized atoms or ions, while nonmetals tend to gain these electrons due to their stronger nuclear charge, resulting in negatively charged ions or polarized atoms.[78]

The number of compounds formed by nonmetals is vast.[79] The first 10 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 2, 2021, were occupied by nonmetals. Hydrogen, carbon, oxygen, and nitrogen collectively appeared in most (80%) of compounds. Silicon, a metalloid, ranked 11th. The highest-rated metal, with an occurrence frequency of 0.14%, was iron, in 12th place.[80] A few examples of nonmetal compounds are: boric acid (H
), used in ceramic glazes;[81] selenocysteine (C
), the 21st amino acid of life;[82] phosphorus sesquisulfide (P4S3), found in strike anywhere matches;[83] and teflon ((C
)n), used to create non-stick coatings for pans and other cookware.[84]


Adding complexity to the chemistry of the nonmetals are anomalies occurring in the first row of each periodic table block; non-uniform periodic trends; higher oxidation states; multiple bond formation; and property overlaps with metals.

First row anomaly[edit]

Condensed periodic table highlighting the first row of each block

Period s-block
1 H

2 Li
3 Na

4 K
5 Rb

6 Cs
7 Fr
Group (1) (2) (3-12) (13) (14) (15) (16) (17) (18)

A first-row anomaly is also present in the d- and f- blocks
however the strength of the anomaly is s >> p > d > f [85]

Starting with hydrogen, the first row anomaly primarily arises from the electron configurations of the elements concerned. Hydrogen is particularly notable for its diverse bonding behaviors. It most commonly forms covalent bonds, but it can also lose its single electron in an aqueous solution, leaving behind a bare proton with tremendous polarizing power.[86] Consequently, this proton can attach itself to the lone electron pair of an oxygen atom in a water molecule, laying the foundation for acid-base chemistry.[87] Moreover, a hydrogen atom in a molecule can form a second, albeit weaker, bond with an atom or group of atoms in another molecule. As Cressey explains, 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."[88]

Hydrogen and helium, as well as boron through neon, have unusually small atomic radii. This phenomenon arises because the 1s and 2p subshells lack inner analogues (meaning there is no zero shell and no 1p subshell), and they therefore experience no electron repulsion effects, unlike the 3p, 4p, and 5p subshells of heavier elements.[89] A a result, ionization energies and electronegativities among these elements are higher than what periodic trends would otherwise suggest. The compact atomic radii of carbon, nitrogen, and oxygen facilitate the formation of double or triple bonds.[90]

While it would normally be expected, on electron configuration consistency grounds, that hydrogen and helium would be placed atop the s-block elements, the significant first row anomaly shown by these two elements justifies alternative placements. Hydrogen is occasionally positioned above fluorine, in group 17, rather than above lithium in group 1. Helium is commonly placed above neon, in group 18, rather than above beryllium in group 2.[91]

Secondary periodicity[edit]

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

A secondary periodicity alternation in certain periodic trends becomes evident when descending groups 13 to 15, and to a lesser extent, groups 16 and 17.[92][n 13] Immediately after the first row of d-block metals, from scandium to zinc, the 3d electrons in the p-block elements—specifically, gallium (a metal), germanium, arsenic, selenium, and bromine—prove less effective at shielding the increasing positive nuclear charge. This same effect is observed with the emergence of fourteen f-block metals located between barium and lutetium, ultimately leading to atomic radii that are smaller than expected for elements from hafnium (Hf) onward.[94]

Higher oxidation states[edit]

Some nonmetallic elements are able to exhibit oxidation states other than would be indicated by the octet rule, which ordinarily results in valency falling with group number that is –3, –2, –1, or 0. Such states occur in, for example, nitrogen trihydride (NH3), hydrogen sulfide (H2S), hydrogen fluoride (HF), and elemental xenon (Xe). On the other hand, the maximum possible oxidation state increases from +5 in group 15, to +8 in group 18. The +5 oxidation state is found in period 2 onwards, for example in nitric acid (HNO3) and phosphorus pentafluoride (PCl5). Higher oxidation states in later groups occur only from period 3 onwards, for example, in sulfur hexafluoride (SF6), iodine heptafluoride (IF7), and xenon tetroxide (XeO4). For the heavier nonmetals, their larger atomic radii and lower electronegativity values enable higher bulk coordination numbers that better tolerate higher positive charges.[95]

Multiple bond formation[edit]

A further difference between period 2 elements and others, particularly carbon, nitrogen, and oxygen, lies in their propensity to form multiple bonds. The compounds formed by these elements often exhibit unique stoichiometries and structures, which are not commonly found in elements from lower periods, such as the various nitrogen oxides.[96]

Property overlaps with metals[edit]

While certain elements have traditionally been classified as nonmetals and others as metals, some overlapping of properties occurs. Writing early in the twentieth century, by which time the era of modern chemistry had been well-established,[97] Humphrey[98] observed that:

... these two groups, however, are not marked off perfectly sharply from each other; some nonmetals resemble metals in certain of their properties, and some metals approximate in some ways to the non-metals.

Examples of metal-like properties occurring in nonmetallic elements include:

  • the electrical conductivity of graphite exceeds that of some metals;[n 14]
  • selenium can be drawn into a wire;[57]
  • just over half of nonmetallic elements can form homopolyatomic cations;[n 15] and
  • silicon has an electronegativity (1.9) comparable with metals such as cobalt (1.88), copper (1.9), nickel (1.91) and silver (1.93).[74]

Types [edit]

Noble gases: He, Ne, Ar, Kr, Xe, Rn; Halogen nonmetals: F, Cl, Br, I; Unclassified nonmetals: H, C, N, P, O, S, Se; Metalloids: B, Si, Ge, As, Sb, Te. Nearby metals are Al, Ga, In, Tl; Sn, Pb; Bi; Po; and At. The nonmetals N, S and I are shown as moderately strong oxidizing agents; O, F, Cl and Br are relatively strong oxidizing agents.
Periodic table excerpt highlighting the four types of nonmetals. Hydrogen is typically found in group 1, but occasionally placed in group 17.
† moderately strong oxidizing agents
‡ strong oxidizing agents[n 16]

The classification of nonmetals can vary, with approaches ranging from as few as two types to as many as six or seven. For instance, the periodic table in the Encyclopaedia Britannica recognizes noble gases, halogens, and other nonmetals, and splits the elements commonly recognized as metalloids between "other metals" and "other nonmetals".[113] On the other hand, on the Royal Society of Chemistry periodic table includes both nonmetals and metals (or nonmetals only) in seven of twelve color categories and shows metalloids in both its metal and nonmetal lists.[114][n 17]

Traversing the periodic table from right to left, three or four types of nonmetals can be discerned:

  • the relatively inert noble gases;[115]
  • a set of chemically strong halogen elements—fluorine, chlorine, bromine and iodine—sometimes referred to as nonmetal halogens[116] or halogen nonmetals[117] (as used here) or stable halogens;[118]
  • a set of unclassified nonmetals, encompassing elements like hydrogen, carbon, nitrogen, and oxygen, for which there is no widely recognized collective name;[n 19] and
  • the chemically weak nonmetallic metalloids[127] which are sometimes considered nonmetals and sometimes considered a third category distinct from metals and nonmetals.[n 20]

The boundaries between these sets of nonmetals are not sharp.[n 21] Carbon, phosphorus, selenium, and 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.[130]

The greatest discrepancy between authors occurs in the metalloid "frontier territory".[131] Some consider metalloids distinct from both metals and nonmetals, while others classify them as nonmetals.[132] Some categorize certain metalloids as metals (e.g., arsenic and antimony due to their similarities to heavy metals).[133][n 22] This article includes metalloids for comparative purposes[n 23] and due to their relatively low densities, high electronegativity, and chemical behavior.[127]

Noble gases[edit]

a glass tube, held upside down by some tongs, has a clear-looking ice-like plug in it which is slowly melting judging from the clear drops falling out of the open end of the tube
A small (about 2 cm long) piece of rapidly melting argon ice

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 due to their exceptionally low chemical reactivity.[115]

These elements exhibit remarkably similar properties, characterized by their colorlessness, odorlessness, and nonflammability. Due to their closed outer electron shells, noble gases possess feeble interatomic forces of attraction, leading to exceptionally low melting and boiling points.[134] As a consequence, they all exist as gases under standard conditions, even those with atomic masses surpassing many typically solid elements.[135]

Chemically, the noble gases exhibit relatively high ionization energies, negligible or negative electron affinities, and high to very high electronegativities. The number of compounds formed by noble gases is in the hundreds and continues to expand,[136] with most of these compounds involving the combination of oxygen or fluorine with either krypton, xenon, or radon.[137]

About 1015 tonnes of noble gases are present in the Earth's atmosphere.[138] Additionally, natural gas can contain as much as 7% helium.[139] Radon diffuses out of rocks, where it forms during the natural decay sequence of uranium and thorium.[140] In the Earth's core there may be around 1013 tons of xenon, in the form of stable XeFe3 and XeNi3 intermetallic compounds.[n 24] This could explain why "studies of the Earth's atmosphere have shown that more than 90% of the expected amount of Xe is depleted."[142]

Halogen nonmetals[edit]

Silver chunks covered be a clear liquid in a sealed bottle
A translucent pale yellow gas in a sealed bottle
A small pile of white crystals in front of a tipped-over cylindrical with a few grains spilling out of the holes in its screw-top lid
sodium (Na), chlorine (Cl), and table salt (NaCl)
Corrosive chlorine, a halogen nonmetal, combines with highly reactive sodium to form stable, unreactive table salt.

Although the halogen nonmetals are notably reactive and corrosive elements, they can also be found in everyday compounds like toothpaste (NaF); common table salt (NaCl); swimming pool disinfectant (NaBr); or food supplements (KI). The term "halogen" itself means "salt former".[143]

Physically, fluorine and chlorine exist as pale yellow and yellowish-green gases, respectively, while bromine is a reddish-brown liquid, typically covered by a layer of its fumes; iodine, when observed under white light, appears as a metallic-looking[102] solid. Electrically, the first three elements function as insulators while iodine behaves as a semiconductor (along its planes).[144]

Chemically, the halogen nonmetals exhibit high ionization energies, electron affinities, and electronegativity values, and are mostly relatively strong oxidizing agents.[145] These characteristics contribute to their corrosive nature.[146] All four elements tend to form primarily ionic compounds with metals,[147] in contrast to the remaining nonmetals (except for oxygen) which tend to form primarily covalent compounds with metals.[n 25] The highly reactive and strongly electronegative nature of the halogen nonmetals epitomizes nonmetallic character.[151]

The halogen nonmetals are commonly found in salt-related minerals. Fluorine, for instance, is present in fluorite (CaF2), a mineral found widely. Chlorine, bromine, and iodine are typically found in brines. Exceptionally, a study reported in 2012 noted the presence of 0.04% native fluorine (F
) by weight in antozonite, attributing these inclusions to radiation from tiny amounts of uranium.[152]


a cluster of bright cherry-red crystals
A crystal of realgar, also known as "ruby sulphur" or "ruby of arsenic", an arsenic sulfide mineral As4S4. The two elements involved each have a predominately nonmetallic chemistry.[153]

The six elements more commonly recognized as metalloids are boron, silicon, germanium, arsenic, antimony, and tellurium, all of which have a metallic appearance. (There are other elements less commonly recongised as metalloids, including carbon, aluminium, selenium and polonium. They have metallic and nonmetallic properties, but one or the other kind predominates.) On a standard periodic table, they occupy a diagonal region within the p-block extending from boron at the upper left to tellurium at the lower right, along the dividing line between metals and nonmetals shown on some tables.[9]

They are brittle and poor-to-good conductors of heat and electricity. Specifically, boron, silicon, germanium, and tellurium are semiconductors. Arsenic and antimony have the electronic structures of semimetals, although both have less stable semiconducting forms.[9]

Chemically, 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. Additionally, they tend to form alloys when combined with metals.[9]

The metalloids are commonly found combined with oxygen, sulfur, or, in the case of tellurium, gold or silver.[154] Boron is typically found in boron-oxygen borate minerals, including in volcanic spring waters. Silicon is present in the silicon-oxygen mineral silica (sand). Germanium, arsenic, and antimony are mainly found as components of sulfide ores. Tellurium is often found in telluride minerals of gold or silver. In some instances, native forms of arsenic, antimony, and tellurium have been reported.[155]

Unclassified nonmetals[edit]

A small glass jar filled with small dull grey concave buttons. The pieces of selenium look like tiny mushrooms without their stems.
Selenium conducts electricity around 1,000 times better when light falls on it, a property used in light-sensing applications.[156]

After classifying the nonmetallic elements into noble gases, halogens, and metalloids, the remaining seven nonmetals are hydrogen, carbon, nitrogen, oxygen, phosphorus, sulfur, and selenium.

In their most stable forms, three of these are colorless gases (H, N, O); three have a metal-like appearance (C, P, Se); and one appears yellow (S). Electrically, graphitic carbon behaves as a semimetal along its planes[157] and a semiconductor perpendicular to its planes;[158] phosphorus and selenium are semiconductors;[159] while hydrogen, nitrogen, oxygen, and sulfur are insulators.[n 26]

These elements are often considered too diverse to merit a collective classification,[161] and have been referred to as other nonmetals,[162] or simply as nonmetals, located between the metalloids and the halogens.[163] As a result, their chemistry is typically taught disparately, according to their respective periodic table groups:[164] hydrogen in group 1; the group 14 nonmetals (including carbon, and possibly silicon and germanium); the group 15 nonmetals (including nitrogen, phosphorus, and possibly arsenic and antimony); and the group 16 nonmetals (including oxygen, sulfur, selenium, and possibly tellurium). Authors may choose other subdivisions based on their preferences.[n 27]

Hydrogen, in particular, behaves in some respects like a metal and in others like a nonmetal.[166] Like a metal it can, for example, form a solvated cation in aqueous solution;[167] it can substitute for alkali metals in compounds such as the chlorides (NaCl cf. HCl) and nitrates (KNO3 cf. HNO3), and in certain alkali metal organometallic structures;[168] and it can form alloy-like hydrides with some transition metals.[169] Conversely, it is an insulating diatomic gas, akin to the nonmetals nitrogen, oxygen, fluorine and chlorine. In chemical reactions, it tends to ultimately attain the electron configuration of helium (the following noble gas) behaving in this way as a nonmetal.[170] It attains this configuration by forming a covalent or ionic bond[171] or, if it has initially given up its electron, by attaching itself to a lone pair of electrons.[172]

Some or all of these nonmetals share several properties. Being less reactive than the halogens,[173] they can occur naturally in the environment.[174] They have significant roles in biology[175] and geochemistry.[161] Collectively, their physical and chemical characteristics can be described as "moderately non-metallic".[161] However, they all have corrosive aspects. Hydrogen can corrode metals. Carbon corrosion can occur in fuel cells.[176] Acid rain is caused by dissolved nitrogen or sulfur. Oxygen causes iron to corrode via rust. White phosphorus, the most unstable form, ignites in air and leaves behind phosphoric acid residue.[177] Untreated selenium in soils can lead to the formation of corrosive hydrogen selenide gas.[178] When combined with metals, the unclassified nonmetals can form high-hardness (interstitial or refractory) compounds[179] due to their relatively small atomic radii and sufficiently low ionization energies.[161] They also exhibit a tendency to bond to themselves, particularly in solid compounds.[180] Additionally, diagonal periodic table relationships among these nonmetals mirror similar relationships among the metalloids.[181]

Unclassified nonmetals are typically found in elemental forms or in association with other elements:[154]

  • Hydrogen is present in the world's oceans as a component of water and occurs in natural gas as a component of methane and hydrogen sulfide.[182]
  • Carbon can be found in limestone, dolomite, and marble, as carbonates.[183] Additionally, carbon exists as graphite, primarily occurring in metamorphic silicate rocks,[184] resulting from the compression and heating of sedimentary carbon compounds.[185]
  • Oxygen is found in the atmosphere; in the oceans as a component of water; and in the Earth's crust as oxide minerals.[186]
  • Phosphorus minerals are widespread, typically appearing as phosphorus-oxygen phosphates.[187]
  • Elemental sulfur can be found in or near hot springs and volcanic regions around the world, while sulfur minerals are common and are often found as sulfides or oxygen-sulfur sulfates.[188]
  • Selenium is found in metal sulfide ores, where it may partially replace sulfur. In rare instances, elemental selenium can also be found.[189]

Abundance, sources, and uses[edit]

Abundance of nonmetallic elements[edit]

Approximate composition (by weight) of
primary components & next most abundant
Universe[190] H 70.5%, He 27.5% O 1%
Atmosphere[191] N 78%, O 21% Ar 0.5%
Hydrosphere[191] O 66.2%, H 33.2% Cl 0.3%
Biomass[192] O 63%, C 20%, H 10% N 3.0%
Crust[191] O 61%, Si 20% H 2.9%

Hydrogen and helium dominate the universe, making up an estimated 98% of all ordinary matter by mass.[n 28] Oxygen, the next most abundant element, constitutes around 1% of the universe's composition.[194]

Five nonmetals—hydrogen, carbon, nitrogen, oxygen, and silicon—dominate the accessible structure of the earth, forming the vast majority of the Earth's crust, atmosphere, hydrosphere, and biomass as shown in the accompanying table.[195]

Sources of nonmetallic elements[edit]

Group (1, 13−18) Period
13 14 15 16 1/17 18 (1−6)
  H He 1
  B C N O F Ne 2
  Si P S Cl Ar 3
  Ge As Se Br Kr 4
  Sb Te I Xe 5
  Rn 6

Nonmetals and metalloids are extracted in their raw forms from:[174]

   mineral ores—boron (borate minerals); carbon (coal; diamond; graphite); fluorine (fluorite); silicon (silica); phosphorus (phosphates); antimony (stibnite, tetrahedrite); iodine (in sodium iodate and sodium iodide);

   mining byproducts—germanium (zinc ores); arsenic (copper and lead ores); selenium and tellurium (copper ores); and radon (uranium-bearing ores);

   liquid air—nitrogen, oxygen, neon, argon, krypton, xenon;

   natural gas—hydrogen (methane), helium, sulfur (hydrogen sulfide); and

   seawater brine—chlorine, bromine, iodine.

Uses of nonmetallic elements[edit]

Nearly all nonmetals have uses in:[196][197]
Household goods, lighting and lasers, and medicine and pharmaceuticals
Most nonmetals have uses in:[196][198]
Agrochemicals, dyestuffs and smart phones
Some nonmetals have uses in or as:[196][199]
Alloys, cryogenics and refrigerants, explosives, fire retardants, fuel cells, inert air replacements, insulation, mineral acids, nuclear control rods, photography, plastics, plug-in hybrid vehicles, solar cells, water treatment, welding gases, and vulcanization
Metalloids have uses in:[200]
Alloys, ceramics, oxide glasses, solar cells, and semiconductors

Nonmetallic elements have distinct properties[201] that enable a wide range of natural and technological uses. In living organisms, hydrogen, oxygen, carbon, and nitrogen serve as the foundational building blocks of life.[202] Some key technological uses of nonmetallic elements are in lighting and lasers, medicine and pharmaceuticals, and ceramics and plastics. The accompanying table groups nonmetallic elements according to their uses.

Some specific uses of later-discovered or rarer nonmetallic elements include:

  • Germanium, thought to be a metal up until the 1930s,[208] was historically used in electronics, particularly early transistors and diodes, and still has roles in specialized high-frequency electronics. It is also used in the production of infrared optical components for thermal imaging and spectroscopy.[209]
  • Radon, rarest of the noble gases,[212] was formerly used in radiography and radiation therapy. Usually, radium in either an aqueous solution or as a porous solid was stored in a glass vessel. The radium decayed to produce radon, which was pumped off, filtered, and compressed into a small tube every few days. The tube was then sealed and removed. It was a source of gamma rays which came from bismuth-214, one of radon’s decay products.[213] Radon has now been replaced by sources of 137Cs, 192Ir, and 103Pd.[214]

History, background, and taxonomy[edit]


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.

Most nonmetallic elements were identified during the 18th and 19th centuries. However, a few nonmetals were recognized in ancient times and later historical periods. Carbon, sulfur, and antimony were among the early nonmetals known to humanity. The discovery of arsenic can be traced back to the Middle Ages, credited to the work of Albertus Magnus. A significant moment in the history of nonmetal discovery occurred in 1669 when Hennig Brand successfully isolated phosphorus from urine. Helium, identified in 1868, holds a unique distinction as the only element not initially discovered on Earth itself.[n 29] Radon is the most recently identified nonmetal, with its detection occurring at the end of the 19th century.[174]

The isolation of nonmetallic elements depended on a range of chemical and physical techniques. These methods encompassed spectroscopy, fractional distillation, radiation detection, electrolysis, ore acidification, displacement reactions, combustion, and controlled heating processes. While some nonmetals were naturally occurring as free elements, others required intricate extraction procedures:

  • The noble gases, renowned for their low reactivity, were first identified via spectroscopy, air fractionation, and radioactive decay studies. Helium was initially detected by its distinctive yellow line in the solar corona spectrum. Subsequently, it was observed escaping as bubbles when uranite UO2 was dissolved in acid. Neon, argon, krypton, and xenon were obtained through the fractional distillation of air. The discovery of radon occurred three years after Henri Becquerel's pioneering research on radiation in 1896.[216]
  • The isolation of halogen nonmetals from their halides involved techniques including electrolysis, acid addition, or displacement. These efforts were not without peril, as some chemists tragically[217] lost their lives in their pursuit of isolating fluorine.[218]
  • The unclassified nonmetals have a diverse history. Hydrogen was discovered and first described in 1671 as the product of the reaction between iron filings and dilute acids. Carbon was found naturally in forms like charcoal, soot, graphite, and diamond. Nitrogen was discovered by examining air after carefully removing oxygen. Oxygen itself was obtained by heating mercurous oxide. Phosphorus was derived from the heating of ammonium sodium hydrogen phosphate (Na(NH4)HPO4), a compound found in urine.[219] Sulfur occurred naturally as a free element, simplifying its isolation. Selenium,[n 30] was first identified as a residue in sulfuric acid.[221]
  • Metalloids were commonly isolated by heating of their oxides (boron, silicon, arsenic, tellurium) or a sulfide (germanium).[174] Antimony was obtained primarily through the heating of its sulfide, stibnite; it was later discovered in native form.[222]

Origin and use of the term[edit]

An extract from the English translation of Lavoisier's Traité élémentaire de chimie (1789),[223] listing the elemental gases oxygen, hydrogen and nitrogen (and erroneously including light and caloric), and the nonmetallic substances sulfur, phosphorus, and carbon, and including the chloride, fluoride and borate ions

Although a distinction had existed between metals and other mineral substances since ancient times, it was only towards the end of the 18th century that a basic classification of chemical elements as either metallic or nonmetallic substances began to emerge. It would take another nine decades before the term "nonmetal" was widely adopted.

Around the year 340 BCE, in Book III of his treatise Meteorology, the ancient Greek philosopher Aristotle categorized substances found within the Earth into two distinct groups: metals and "fossiles".[n 31] The latter category included various minerals such as realgar, ochre, ruddle, sulfur, cinnabar, and other substances that he referred to as "stones which cannot be melted".[224]

Up until the Middle Ages the classification of minerals remained largely unchanged, albeit with varying terminology. In the fourteenth century, an English alchemist named Richardus Anglicus expanded upon the classification of minerals in his work Correctorium Alchemiae. In this text, he proposed the existence of two primary types of minerals. The first category, which he referred to as "major minerals", included well-known metals such as gold, silver, copper, tin, lead, and iron. On the other hand, the second category, labeled as "minor minerals", encompassed substances like salts, atramenta (iron sulfate), alums, vitriol, arsenic, orpiment, sulfur, and similar substances that were not metallic bodies.[225]

The term "nonmetallic" has historical origins dating back to at least the 16th century. In a 1566 medical treatise, the French physician Loys de L'Aunay discussed the distinct properties exhibited by substances derived from plant sources. In his writings, he made a significant comparison between the characteristics of materials originating from what he referred to as metallic soils and non-metallic soils.[226]

Later, the French chemist Nicolas Lémery discussed metallic minerals and nonmetallic minerals in his work Universal Treatise on Simple Drugs, Arranged Alphabetically published in 1699. In his writings, he contemplated whether the substance "cadmia" belonged to either the first category, akin to cobaltum (cobaltite), or the second category, exemplified by what was then known as calamine—a mixed ore containing zinc carbonate and silicate.[227]

The pivotal moment in the systematic classification of chemical elements, distinguishing between metallic and nonmetallic substances, came in 1789 with the groundbreaking work of Antoine Lavoisier. Lavoisier, a French chemist, published the first modern list of chemical elements in his revolutionary[228] work Traité élémentaire de chimie. In this work he categorized elements into distinct groups, including gases, metallic substances, nonmetallic substances, and earths (heat-resistant oxides).[229] Lavoisier's work gained widespread recognition and was republished in twenty-three editions across six languages within its first seventeen years, significantly advancing the understanding of chemistry in Europe and America.[230]

The eventual and widespread adoption of the term "nonmetal" followed a complex and lengthy developmental process that spanned nearly nine decades. In 1811, the Swedish chemist Berzelius introduced the term "metalloids"[231] to describe nonmetallic elements, noting their ability to form negatively charged ions with oxygen in aqueous solutions.[232][233] While Berzelius' terminology gained significant acceptance,[234] it later faced criticism from some who found it counterintuitive,[233] misapplied,[235] or even invalid.[236][237] In 1864, reports indicated that the term "metalloids" was still endorsed by leading authorities,[238] but there were reservations about its appropriateness. The idea of designating elements like arsenic as metalloids had been considered.[238] By as early as 1866, some authors began preferring the term "nonmetal" over "metalloid" to describe nonmetallic elements.[239] In 1875, Kemshead[240] observed that elements were categorized into two groups: non-metals (or metalloids) and metals. He noted that the term "non-metal", despite its compound nature, was more precise and had become universally accepted as the nomenclature of choice.

Suggested distinguishing criteria[edit]

Some single properties used to distinguish metals and nonmetals

In 1809, the British chemist and inventor Humphry Davy made a groundbreaking discovery that reshaped the understanding of metals and nonmetals.[262] His isolation of sodium and potassium represented a significant departure from the conventional method of classifying metals solely based on their ponderousness or high densities.[263] Sodium and potassium, on the contrary, floated on water.[n 33] Nevertheless, their classification as metals was firmly established by their distinct chemical properties.[266]

As early as 1811, attempts were initiated to enhance the differentiation between metals and nonmetals by examining a range of properties, including physical, chemical, and electron-related characteristics. The table provided here outlines 22 such properties, sorted by type and year of mention.

One of the most commonly recognized properties used in this context is the effect of heating on electrical conductivity. As temperature rises, the conductivity of metals decreases while that of nonmetals increases.[253] However, plutonium, carbon, arsenic, and antimony defy the norm. When plutonium (a metal) is heated within a temperature range of −175 to +125 °C its conductivity increases.[267] Similarly, despite its common classification as a nonmetal, when carbon (as graphite) is heated it experiences a decrease in electrical conductivity.[268] Arsenic and antimony, which are occasionally classified as nonmetals, show behavior similar to carbon, highlighting the complexity of the distinction between metals and nonmetals.[269]

Kneen and colleagues[270] proposed that the classification of nonmetals can be achieved by establishing a single criterion for metallicity. They acknowledged that various plausible classifications exist and emphasized that while these classifications may differ to some extent, they would generally agree on the categorization of nonmetals.

However, Emsley[271] pointed out the complexity of this task, asserting that no single property alone can unequivocally assign elements to either the metal or nonmetal category. Furthermore, Jones[272] emphasized that classification systems typically rely on more than two attributes to define distinct types.

Characteristics of
nonmetals according to Johnson[273]
Tier Elements
Gaseous H, N, O, F, Cl, noble gases
Other insulator S, Br
Semiconductor B, Si, Ge, P, Se, Te, I
Soft and crumbly
conductor; acidic oxide
C, As, Sb[n 34]
All other elements are metals

An approach to distinguishing between metallic and nonmetallic properties was suggested by Johnson,[273] emphasizing the significance of physical properties, while acknowledging the potential need for other properties in certain ambiguous cases. His observations highlighted several key distinctions:

  1. Physical state—Elements that exist as gases or are nonconductors are typically classified as nonmetals.
  2. Solid nonmetals—Solid nonmetals exhibit characteristics such as hardness and brittleness (B, Si, Ge) or softness and crumbliness, setting them apart from metals that are generally malleable and ductile.
  3. Chemical behavior—Nonmetal oxides tend to be acidic, providing another useful criterion for identifying nonmetals.

Metals and nonmetals sorted by
density and electronegativity (EN)[n 35]
Density < 1.9 ≥ 1.9
< 7 gm/cm3 Groups 1 and 2
Sc, Y, La
Ce, Pr, Eu, Yb
Ti, Zr, V; Al, Ga
Noble gases
F, Cl, Br, I
H, C, N, P, O, S, Se
B, Si, Ge, As, Sb, Te^
> 7 gm/cm3 Nd, Pm, Sm, Gd, Tb, Dy
Ho, Er, Tm, Lu; Ac–Es;
Hf, Nb, Ta; Cr, Mn, Fe,
Co, Zn, Cd, In, Tl, Pb
Ni, Mo, W, Tc, Re,
Platinum group metals,
Coinage metals, Hg; Sn,
Bi, Po, At
^ italicized elements are commonly recognized by some authors as metalloids

Several authors[280] have noted that, in general, and among other properties, nonmetals have low densities and high electronegativity, which is consistent with the data presented in the table. Nonmetallic elements are predominantly located in the top right quadrant of this table, where density is low and electronegativity values are relatively high. In contrast, the other three quadrants are primarily occupied by metals. Goldwhite and Spielman[281] added that, "... lighter elements tend to be more electronegative than heavier ones." The average electronegativity for the elements in the table with densities less than 7 gm/cm3 (metals and nonmetals) is 2.09 compared to 1.68 for the metals having densities of more than 7 gm/cm3.

While some authors choose to further subdivide elements into metals, metalloids, and nonmetals, Oderberg[282] disagrees with this approach. He argues that according to the principles of categorization, anything not classified as a metal should be considered a nonmetal.

Development of types[edit]

A side profile set in stone of a distinguished French gentleman
Gaspard Alphonse Dupasquier (1793–1848), French doctor, pharmacist and chemist as depicted in the Monument aux Grands Hommes de la Martinière [fr] in Lyon, France. In 1844 he put forward a basic taxonomy of nonmetals.

In 1844, Alphonse Dupasquier [fr], a French doctor, pharmacist, and chemist,[283] established a basic taxonomy of nonmetals to aid in the study of these elements. He wrote:[284]

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 fourfold classification has echoes in the modern types of nonmetals. The organogens and sulphuroids are akin to the unclassified nonmetals. The chloroide nonmetals were later recognized independently as halogens.[285] The boroid nonmetals eventually evolved into the metalloids, with this classification beginning as early as 1864.[238] The noble gases were also identified as a distinct group among the nonmetals, dating back to as early as 1900.[286]

Comparison of selected properties[edit]

The two tables in this section list some physical and chemical properties of metals[n 36] and those of the three to four types of nonmetals, based on the most stable forms of the elements in ambient conditions.

The aim is to show that most properties display a left-to-right progression in metallic-to-nonmetallic character or average values.[287][288] Some overlapping of boundaries can occur as outlier elements of each type exhibit less-distinct, hybrid-like, or atypical properties.[289][n 37] These overlaps or transitional points, along with horizontal, diagonal, and vertical relationships between the elements, form part of the "great deal of information" summarized by the periodic table.[291]

The dashed lines around the columns for metalloids signify that the treatment of these elements as a distinct type can vary depending on the author, or classification scheme in use.


Physical properties are presented in loose order of ease of their determination.

Element type
Property Metals Metalloids Unc. nonmetals Halogen nonmetals Noble gases
Form and density[292] solid solid solid or gas solid, liquid or gas gas
often high density such as Fe, Pb, W low to moderately high density low density low density low density
some light metals including Be, Mg, Al all lighter than Fe H, N lighter than air[293] He, Ne lighter than air[294]
Appearance lustrous[23] lustrous[295]
  • ◇ lustrous: C, P, Se[296]
  • ◇ colorless: H, N, O[297]
  • ◇ colored: S[298]
  • ◇ colored: F, Cl, Br[299]
  • ◇ lustrous: I[9]
Elasticity mostly malleable and ductile[23] (Hg is liquid) brittle[295] C, black P, S, Se brittle[n 38] iodine is brittle[303] not applicable
Electrical conductivity good[n 39]
  • ◇ moderate: B, Si, Ge, Te
  • ◇ good: As, Sb[n 40]
  • ◇ poor: H, N, O, S
  • ◇ moderate: P, Se
  • ◇ good: C[n 41]
  • ◇ poor: F, Cl, Br
  • ◇ moderate: I[n 42]
poor[n 43]
Electronic structure[306] metallic (Be, Sr, α-Sn, Yb, Bi are semimetals) semimetal (As, Sb) or semiconductor
  • ◇ semimetal: C
  • ◇ semiconductor: P, Se
  • ◇ insulator: H, N, O, S
semiconductor (I) or insulator insulator


Chemical properties start with general characteristics and proceed to more specific details.

Element type
Property Metals Metalloids Unc. nonmetals Halogen nonmetals Noble gases
General chemical behavior
weakly nonmetallic[n 44] moderately nonmetallic[288] strongly nonmetallic[309]
  • ◇ inert to nonmetallic[310]
  • ◇ Rn shows some cationic behavior[311]
Oxides basic; some amphoteric or acidic[312] amphoteric or weakly acidic[313][n 45] acidic[n 46] or neutral[n 47] acidic[n 48] metastable XeO3 is acidic;[318] stable XeO4 strongly so[319]
few glass formers[n 49] all glass formers[321] some glass formers[n 50] no glass formers reported no glass formers reported
ionic, polymeric, layer, chain, and molecular structures[323] polymeric in structure[324]
  • ◇ mostly molecular[324]
  • ◇ C, P, S, Se have at least one polymeric form
  • ◇ mostly molecular
  • ◇ iodine has at least one polymeric form, I2O5[325]
  • ◇ mostly molecular
  • XeO2 is polymeric[326]
Compounds with metals alloys[23] or intermetallic compounds[327] tend to form alloys or intermetallic compounds[328]
  • ◇ salt-like to covalent: H†, C, N, P, S, Se[329]
  • ◇ mainly ionic: O[330]
mainly ionic[147] simple compounds in ambient conditions not known[n 51]
Ionization energy (kJ mol−1)[332] ‡ low to high moderate moderate to high high high to very high
376 to 1,007 762 to 947 941 to 1,402 1,008 to 1,681 1,037 to 2,372
average 643 average 833 average 1,152 average 1,270 average 1,589
Electronegativity (Pauling)[n 52][74] ‡ low to high moderate moderate to high high high (Rn) to very high
0.7 to 2.54 1.9 to 2.18 2.19 to 3.44 2.66 to 3.98 ca. 2.43 to 4.7
average 1.5 average 2.05 average 2.65 average 3.19 average 3.3

† Hydrogen can also form alloy-like hydrides[169]
‡ The labels low, moderate, high, and very high are arbitrarily based on the value spans listed in the table

See also[edit]


  1. ^ By weight, O/Si/H comprise 83.9% of the crust; N/O, 99% of the atmosphere; O/H, 99.4% of the hydrosphere; and O/C/H/N, 96% of the biomass.
  2. ^ While the oxides of most metals are basic, an appreciable number are either amphoteric or acidic.[5]
  3. ^ Metallic or nonmetallic character has usually been taken to be indicated by one property rather than two or more
  4. ^ A 2D semiconductor with a metallic appearance, showing evidence of delocalized electrons[17]
  5. ^ Solid iodine has a silvery metallic appearance under white light at room temperature.[21] It sublimes at ordinary and higher temperatures, passing from solid to gas; its vapours are violet-colored.[22]
  6. ^ The solid nonmetals have electrical conductivity values ranging from 10−18 S•cm−1 for sulfur[25] to 3 × 104 in graphite[26] or 3.9 × 104 for arsenic;[27] cf. 0.69 × 104 for manganese to 63 × 104 for silver, both metals.[25] The conductivity of graphite (a nonmetal) and arsenic (a metalloid nonmetal) exceeds that of manganese. Such overlaps show that it can be difficult to draw a clear line between metals and nonmetals.
  7. ^ The absorbed light may be converted to heat or re-emitted in all directions so that the emission spectrum is thousands of times weaker than the incident light radiation[46]
  8. ^ Thermal conductivity values for metals range from 6.3 W m−1 K−1 for neptunium to 429 for silver; cf. antimony 24.3, arsenic 50, and carbon 2000.[25] Electrical conductivity values of metals range from 0.69 S•cm−1 × 104 for manganese to 63 × 104 for silver; cf. carbon 3 × 104,[26] arsenic 3.9 × 104 and antimony 2.3 × 104.[25]
  9. ^ These elements being semiconductors.[51]
  10. ^ While CO and NO are commonly referred to as being neutral, CO is a slightly acidic oxide, reacting with bases to produce formates (CO + OH → HCOO);[71] and in water, NO reacts with oxygen to form nitrous acid HNO2 (4NO + O2 + 2H2O → 4HNO2).[72]
  11. ^ F−I: 3.98 + 3.16 + 2.96 + 2.66 = 12.76/4 = 3.19
  12. ^ B−Te: 2.04 + 1.9 + 2.01 + 2.18 + 2.05 + 2.1 = 12.28/6 = 2.04
  13. ^ The net result is an even-odd difference between periods (except in the s-block) that is sometimes known as secondary periodicity: elements in even periods have smaller atomic radii and prefer to lose fewer electrons, while elements in odd periods (except the first) differ in the opposite direction. Many properties in the p-block then show a zigzag rather than a smooth trend along the group. For example, phosphorus and antimony in odd periods of group 15 readily reach the +5 oxidation state, whereas nitrogen, arsenic, and bismuth in even periods prefer to stay at +3.[93]
  14. ^ For example, the conductivity of graphite is 3 × 104 S•cm−1[99] whereas that of manganese is 6.9 × 103 S•cm−1[100]
  15. ^ A homopolyatomic cation consists of two or more atoms of the same element bonded together and carrying a positive charge, for example, N5+, O2+ and Cl4+, Such ions are further known for C, P, Sb, S, Se, Te, Br, I and Xe[101].
  16. ^ 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.[102] The remaining reactive nonmetallic elements have giant covalent structures, but for H which is a diatomic gas.[103]

    The single dagger nonmetals N, S and iodine are somewhat hobbled as to the strength of their nonmetallic character:

    • While N has a high electronegativity, it is a reluctant anion former,[104] and a pedestrian oxidizing agent unless combined with a more active nonmetal like O or F.[105]
    • S reacts in the cold with alkalic and post-transition metals, and Cu, Ag and Hg,[106] 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.[107]
    • Iodine is sufficiently corrosive to cause lesions resembling thermal burns, if handled without suitable protection,[108] and tincture of iodine will smoothly dissolve Au.[109] That said, while "F, Cl and Br will all oxidize Fe2+ (aq) to Fe3+(aq) ... iodine ... is such a [relatively] weak oxidizing agent that it cannot remove electrons from Fe(II) ions to form Fe(III) ions."[110] 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.[111] 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.[112]
  17. ^ Of the twelve categories in the Royal Society periodic table, five only show up with the metal filter, three only with the nonmetal filter, and four with both filters. Interestingly, the six elements marked as metalloids (B, Si, Ge, As, Sb, and Te) show under both filters. Six other elements (113–120: Nh, Fl, Mc, Lv, Ts, and Og), whose status is unknown, also show up under both filters but are not included in any of the twelve color categories.
  18. ^ The quote marks are not found in the source; they are used here to make it clear that the source employs the word non-metals as a formal term for the subset of chemical elements in question, rather than applying to nonmetals generally
  19. ^ Varying configurations of these nonmetals have been referred to as, for example, basic nonmetals,[119] bioelements,[120] central nonmetals,[121] CHNOPS,[122] essential elements,[123] "non-metals",[124][n 18] orphan nonmetals,[125] or redox nonmetals[126]

    The descriptive phrase unclassified nonmetals is used here for convenience.

  20. ^ Tshitoyan et al. (2019) conducted a machine-based analysis of the proximity of names of the elements based on 3.3 million abstracts published between 1922 and 2018 in more than 1,000 journals. The resulting map shows that "chemically similar elements are seen to cluster together and the overall distribution exhibits a topology reminiscent of the periodic table itself".[128]
  21. ^ Such boundary fuzziness and overlap often occur in classification schemes.[129]
  22. ^ Jones 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".[129]
  23. ^ For a related comparison of the properties of metals, metalloids, and nonmetals, see Rudakiya & Patel (2021), p. 36
  24. ^ Xe is expected to be metallic at the pressures encountered in the Earth's core[141]
  25. ^ Metal oxides are usually ionic.[148] On the other hand, oxides of metals with high oxidation states are usually either polymeric or covalent.[149] A polymeric oxide has a linked structure composed of multiple repeating units.[150]
  26. ^ 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[160]
  27. ^ 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.[165]
  28. ^ Ordinary matter – including the stars, planets, and all living creatures – constitutes less than 5% of the universe. The rest – dark energy and dark matter – is as yet poorly understood.[193]
  29. ^ How helium acquired the -ium suffix is explained in the following passage by its discoverer, William Lockyer: "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".[215]
  30. ^ Berzelius, who discovered selenium, thought it had the properties of a metal, combined with the properties of sulfur[220]
  31. ^ Not to be confused with the modern usage of fossil to refer to the preserved remains, impression, or trace of any once-living thing
  32. ^ The Goldhammer-Herzfeld ratio is roughly equal to the cube of the atomic radius divided by the molar volume.[244] More specifically, it is the ratio of the force holding an individual atom's outer electrons in place with the forces on the same electrons from interactions between the atoms in the solid or liquid element. When the interatomic forces are greater than, or equal to, the atomic force, outer electron itinerancy is indicated and metallic behaviour is predicted. Otherwise nonmetallic behaviour is anticipated.
  33. ^ When Davy isolated sodium and potassium their low densities challenged the conventional wisdom that metals were ponderous substances. It was thus proposed to refer to them as metalloids, meaning "resembling metals in form or appearance".[264] This suggestion was ignored; the two new elements were admitted to the metal club in cognizance of their physical properties (opacity, luster, malleability, conductivity) and "their qualities of chemical combination". Hare[265] observed that the line of demarcation between metals and nonmetals had been "annihilated" by the discovery of alkaline metals having a density less than that of water:
    "Peculiar brilliance and opacity were in the next place appealed to as a means of discrimination; and likewise that superiority in the power of conducting heat and electricity ... Yet so difficult has it been to draw the line between metallic…and non-metallic ... that bodies which are by some authors placed in one class, are by others included in the other. Thus selenium, silicon, and zirconion [sic] have by some chemists been comprised among the metals, by others among non-metallic bodies." ...
  34. ^ While antimony trioxide is usually listed as being amphoteric its very weak acid properties dominate over those of a very weak base[274]
  35. ^ (a) Up to element 99 (Es), with the values taken from Aylward and Findlay.[275]
    (b) Weighable amounts of the extremely radioactive elements At (element 85), Fr (87), and elements with an atomic number higher than Es (99), have not been prepared.[276]
    (c) The density values used for At and Fr are theoretical estimates.[277]
    (d) A survey of definitions of the term "heavy metal" reported density criteria ranging from above 3.5 g/cm3 to above 7 g/cm3.[278]
    (e) Vernon specified a minimum electronegativity of 1.9 for the metalloids, on the revised Pauling scale[9]
    (f) Electronegativity values for the noble gases are from Rahm, Zeng and Hoffmann[279]
  36. ^ Metals are included for reference
  37. ^ A similar phenomenon applies more generally to certain Groups of the periodic table where, for example, the noble gases in Group 18 act as bridge between the nonmetals of the p-block and the metals of the s-block (Groups 1 and 2)[290]
  38. ^ All four have less stable non-brittle forms:[301] carbon as exfoliated (expanded) graphite,[52][302] and as carbon nanotube wire;[54] phosphorus as white phosphorus (soft as wax, pliable and can be cut with a knife, at room temperature);[55] sulfur as plastic sulfur;[56] and selenium as selenium wires[57]
  39. ^ Metals have electrical conductivity values of from 6.9×103 S•cm−1 for manganese to 6.3×105 for silver[304]
  40. ^ Metalloids have electrical conductivity values of from 1.5×10−6 S•cm−1 for boron to 3.9×104 for arsenic[305]
  41. ^ Unclassified nonmetals have electrical conductivity values of from ca. 1×10−18 S•cm−1 for the elemental gases to 3×104 in graphite[99]
  42. ^ The halogen nonmetals 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[99][144]
  43. ^ The elemental gases have electrical conductivity values of ca. 1×10−18 S•cm−1[99]
  44. ^ Metalloids always give "compounds less acidic in character than the corresponding compounds of the [typical] nonmetals"[295]
  45. ^ Arsenic trioxide reacts with sulfur trioxide, forming arsenic "sulfate" As2(SO4)3[314]
  46. ^ NO
    , N
    , SO
    , SeO
    are strongly acidic[315]
  47. ^ H2O, CO, NO, N2O are neutral oxides; CO and N2O are "formally the anhydrides of formic and hyponitrous acid, respectively viz. CO + H2O → H2CO2 (HCOOH, formic acid); N2O + H2O → H2N2O2 (hyponitrous acid)"[316]
  48. ^ ClO
    , Cl
    , I
    are strongly acidic[317]
  49. ^ Metals that form glasses are: V; Mo, W; Al, In, Tl; Sn, Pb; Bi[320]
  50. ^ Unclassified nonmetals that form glasses are P, S, Se;[320] CO2 forms a glass at 40 GPa[322]
  51. ^ 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[331]
  52. ^ Values for the noble gases are from Rahm, Zeng and Hoffmann[279]



  1. ^ Restrepo et al. 2006, p. 411; Thornton & Burdette 2010, p. 86; Hermann, Hoffmann & Ashcroft 2013, pp. 11604‒1‒11604‒5
  2. ^ Parkes & Mellor 1943, p. 740
  3. ^ Pascoe 1982, p. 3
  4. ^ Glinka 1973, p. 56; Oxtoby, Gillis & Butler 2015, p. I.23
  5. ^ Liu, Yang & Zheng 2022, p. 31
  6. ^ Godovikov & Nenasheva 2020, p. 4; Sanderson 1957, p. 229; Morely & Muir 1892, p. 241
  7. ^ a b Larrañaga, Lewis & Lewis 2016, p. 988
  8. ^ Steudel 2020, p. 43: Steudel's monograph is an updated translation of the fifth German edition of 2013, incorporating the literature up to Spring 2019.
  9. ^ a b c d e f Vernon 2013
  10. ^ Vernon 2020, p. 220; Rochow 1966, p. 4
  11. ^ IUPAC Periodic Table of the Elements
  12. ^ Johnson 2007, p. 13
  13. ^ Bodner & Pardue 1993, p. 354; Cherim 1971, p. 98
  14. ^ Chen 2021, p. 33; Burrows et al. 2021, p. 1242; Vallabhajosula 2023, p. 214
  15. ^ Vernon 2013, p. 1204
  16. ^ Nefedov et al. 1968, p. 87
  17. ^ Steudel 2020, p. 601
  18. ^ Vasáros & Berei 1985, p. 109; Seaborg 1948, p. 368; Bladel 1949, pp. 51–52; Kleinberg 1950, p. 32; Fearnside, Jones & Shaw 1954, p. 102; Encyclopedia Britannica 1956, vol. 6, p. 823; Furse & Rendle 1975, p. 82; Siekierski & Burgess 2002, pp. 65, 122; Restrepo et al. 2006, p. 411; Thornton & Burdette 2010, p. 86
  19. ^ Hermann, Hoffmann & Ashcroft 2013, pp. 11604‒1‒11604‒5
  20. ^ Mewes et al. 2019; Smits et al. 2020; Florez et al. 2022
  21. ^ Koenig 1962, p. 108
  22. ^ Tidy 1887, pp. 107–108
  23. ^ a b c d Kneen, Rogers & Simpson 1972, pp. 261–264
  24. ^ Phillips 1973, p. 7
  25. ^ a b c d e Aylward & Findlay 2008, pp. 6–12
  26. ^ a b Jenkins & Kawamura 1976, p. 88
  27. ^ Carapella 1968, p. 30
  28. ^ Zumdahl & DeCoste 2010, pp. 455, 456, 469, A40; Earl & Wilford 2021, p. 3-24
  29. ^ Still 2016, p. 120
  30. ^ Wiberg 2001, pp. 780
  31. ^ Wiberg 2001, pp. 824, 785
  32. ^ Earl & Wilford 2021, p. 3-24
  33. ^ Siekierski & Burgess 2002, p. 86
  34. ^ Charlier, Gonze & Michenaud 1994
  35. ^ Taniguchi et al. 1984, p. 867: "... black phosphorus ... [is] characterized by the wide valence bands with rather delocalized nature."; Morita 1986, p. 230; Carmalt & Norman 1998, p. 7: "Phosphorus ... should therefore be expected to have some metalloid properties."; Du et al. 2010. Interlayer interactions in black phosphorus, which are attributed to van der Waals-Keesom forces, are thought to contribute to the smaller band gap of the bulk material (calculated 0.19 eV; observed 0.3 eV) as opposed to the larger band gap of a single layer (calculated ~0.75 eV).
  36. ^ Wiberg 2001, pp. 742
  37. ^ Evans 1966, pp. 124–25
  38. ^ Wiberg 2001, pp. 758
  39. ^ Stuke 1974, p. 178; Donohue 1982, pp. 386–87; Cotton et al. 1999, p. 501
  40. ^ Steudel 2000, p. 601: "... Considerable orbital overlap can be expected. Apparently, intermolecular multicenter bonds exist in crystalline iodine that extend throughout the layer and lead to the delocalization of electrons akin to that in metals. This explains certain physical properties of iodine: the dark color, the luster and a weak electric conductivity, which is 3400 times stronger within the layers then perpendicular to them. Crystalline iodine is thus a two-dimensional semiconductor."; Segal 1989, p. 481: "Iodine exhibits some metallic properties ..."
  41. ^ Cahn & Haasen 1996, p. 4; Boreskov 2003, p. 44
  42. ^ DeKock & Gray 1989, pp. 423, 426—427
  43. ^ Boreskov 2003, p. 45
  44. ^ Wiberg 2001, p. 416; Wiberg is here referring to iodine.
  45. ^ Elliot 1929, p. 629
  46. ^ Fox 2010, p. 31
  47. ^ Wibaut 1951, p. 33: "Many substances ...are colourless and therefore show no selective absorption in the visible part of the spectrum."
  48. ^ Kneen, Rogers & Simpson 1972, pp. 85–86, 237
  49. ^ Salinas 2019, p. 379
  50. ^ Yang 2004, p. 9
  51. ^ Wiberg 2001, pp. 416, 574, 681, 824, 895, 930; Siekierski & Burgess 2002, p. 129
  52. ^ a b Chung 1987
  53. ^ Godfrin & Lauter 1995
  54. ^ a b Janas, Cabrero-Vilatela & Bulmer 2013
  55. ^ a b Faraday 1853, p. 42; Holderness & Berry 1979, p. 255
  56. ^ a b Partington 1944, p. 405
  57. ^ a b c Regnault 1853, p. 208
  58. ^ Edwards 2000, pp. 100, 102–103; Herzfeld 1927, pp. 701–705
  59. ^ Kneen, Rogers & Simpson 1972, pp. 263‒264
  60. ^ Langley & Hattori 2014, p. 214
  61. ^ a b Abbott 1966, p. 18
  62. ^ Brown et al. 2014, p. 237
  63. ^ Barton 2021, p. 200
  64. ^ Borg & Dienes 1992, p. 26
  65. ^ Wiberg 2001, p. 796
  66. ^ Shang et al. 2021
  67. ^ Tang et al. 2021
  68. ^ Steudel 2020, passim; Carrasco et al. 2023; Shanabrook, Lannin & Hisatsune 1981, pp. 130–133
  69. ^ Eagleson 1994, 1169
  70. ^ Moody 1991, p. 365
  71. ^ House 2013, p. 427
  72. ^ Lewis & Deen 1994, p. 568
  73. ^ Yoder, Suydam & Snavely 1975, p. 58
  74. ^ a b c Aylward & Findlay 2008, p. 126
  75. ^ Young et al. 2018, p. 753
  76. ^ Brown et al. 2014, p. 227
  77. ^ Siekierski & Burgess 2002, pp. 21, 133, 177
  78. ^ Moore 2016; Burford, Passmore & Sanders 1989, p. 54
  79. ^ King & Caldwell 1954, p. 17; Brady & Senese 2009, p. 69
  80. ^ Chemical Abstracts Service 2021
  81. ^ Emsley 2011, pp. 81
  82. ^ Cockell 2019, p. 210
  83. ^ Scott 2014, p. 3
  84. ^ Emsley 2011, p. 184
  85. ^ Jensen 1986, p. 506
  86. ^ Lee 1996, p. 240
  87. ^ Greenwood & Earnshaw 2002, p. 43
  88. ^ Cressey 2010
  89. ^ Siekierski & Burgess 2002, pp. 24–25
  90. ^ Siekierski & Burgess 2002, p. 23
  91. ^ Petruševski & Cvetković 2018; Grochala 2018
  92. ^ Kneen, Rogers & Simpson 1972, pp. 226, 360; Siekierski & Burgess 2002, pp. 52, 101, 111, 124, 194
  93. ^ Scerri 2020, pp. 407–420
  94. ^ Greenwood & Earnshaw 2002, pp. 27, 1232, 1234
  95. ^ Cox 2004, p. 146
  96. ^ Cox 2004, p. 146
  97. ^ Dorsey 2023, pp. 12–13
  98. ^ Humphrey 1908
  99. ^ a b c d Bogoroditskii & Pasynkov 1967, p. 77; Jenkins & Kawamura 1976, p. 88
  100. ^ Desai, James & Ho 1984, p. 1160
  101. ^ Engesser & Krossing 2013, p. 947
  102. ^ a b Vernon 2013, p. 1706
  103. ^ Wiberg 2001, passim
  104. ^ Vernon 2020, p. 220
  105. ^ Atkins & Overton 2010, pp. 377, 389
  106. ^ Moody 1991, p. 391
  107. ^ Rodgers 2012, p. 504; Wulfsberg 2000, p. 726
  108. ^ Stellman 1998, chapter 104–211
  109. ^ Nakao 1992, p. 426–427
  110. ^ Hill & Holman 2000, p. 196
  111. ^ Wiberg 2001, pp. 1761–1762
  112. ^ Young 2006, p. 1285
  113. ^ Encyclopaedia Britannica 2021
  114. ^ Royal Society of Chemistry 2021
  115. ^ a b Matson & Orbaek 2013, p. 203
  116. ^ Chambers & Holliday 1982, pp. 273–274; Bohlmann 1992, p. 213; Jentzsch 2015, p. 247
  117. ^ Kernion 2019, p. 191; Cao et al. 2021, pp. 20–21; Hussain et al. 2023
  118. ^ Vassilakis, Kalemos & Mavridis 2014, p. 1; Hanley & Koga 2018, p. 24; Kaiho 2017, ch. 2, p. 1
  119. ^ Williams 2007, pp. 1550–1561: H, C, N, P, O, S
  120. ^ Wächtershäuser 2014, p. 5: H, C, N, P, O, S, Se
  121. ^ Hengeveld & Fedonkin, pp. 181–226: C, N, P, O, S
  122. ^ Wakeman 1899, p. 562
  123. ^ Fraps 1913, p. 11: H, C, Si, N, P, O, S, Cl
  124. ^ Parameswaran at al. 2020, p. 210: H, C, N, P, O, S, Se
  125. ^ Knight 2002, p. 148: H, C, N, P, O, S, Se
  126. ^ Fraústo da Silva & Williams 2001, p. 500: H, C, N, O, S, Se
  127. ^ a b Bailar et al. 1989, p. 742
  128. ^ Tshitoyan et al. 2019, pp. 95–98
  129. ^ a b Jones 2010, pp. 169–71
  130. ^ Stein 1983, p. 165
  131. ^ Russell & Lee 2005, p. 419
  132. ^ Goodrich 1844, p. 264; The Chemical News 1897, p. 189; Hampel & Hawley 1976, pp. 174, 191; Lewis 1993, p. 835; Hérold 2006, pp. 149–50
  133. ^ Tyler 1948, p. 105; Reilly 2002, pp. 5–6
  134. ^ Jolly 1966, p. 20
  135. ^ Clugston & Flemming 2000, pp. 100–101, 104–105, 302
  136. ^ Maosheng 2020, p. 962
  137. ^ Mazej 2020
  138. ^ Cox 2000, pp. 258–259; Möller 2003, p. 173; Trenberth & Smith 2005, p. 864
  139. ^ Emsley 2011, p. 220
  140. ^ Emsley 2011, p. 440
  141. ^ Lee & Steinle-Neumann 2006, p. 1
  142. ^ Zhu et al. 2014, pp. 644–648
  143. ^ Wiberg 2001, pp. 4022
  144. ^ a b Greenwood & Earnshaw 2002, p. 804
  145. ^ Rudolph 1973, p. 133: "Oxygen and the halogens in particular ... are therefore strong oxidizing agents."
  146. ^ Daniel & Rapp 1976, p. 55
  147. ^ a b Cotton et al. 1999, p. 554
  148. ^ Woodward et al. 1999, pp. 133–194
  149. ^ Phillips & Williams 1965, pp. 478–479
  150. ^ Moeller et al. 2012, p. 314
  151. ^ Lanford 1959, p. 176
  152. ^ Schmedt, Mangstl & Kraus 2012, p. 7847‒7849
  153. ^ Bailar, Moeller & Kleinberg 1965, p. 477; Mee 1964, p. 153
  154. ^ a b Cox 1997, pp. 130–132; Emsley 2011, passim
  155. ^ Hurlbut 1961, p. 132
  156. ^ Emsley 2011, p. 478
  157. ^ Greenwood & Earnshaw 2002, p. 277
  158. ^ Atkins et al. 2006, p. 320
  159. ^ Greenwood & Earnshaw 2002, p. 482; Berger 1997, p. 86
  160. ^ Moss 1952, pp. 180, 202
  161. ^ a b c d Cao et al. 2021, p. 20
  162. ^ Challoner 2014, p. 5; Government of Canada 2015; Gargaud et al. 2006, p. 447
  163. ^ Crichton 2012, p. 6; Scerri 2013; Los Alamos National Laboratory 2021
  164. ^ Vernon 2020, p. 218
  165. ^ Wulfsberg 2000, pp. 273–274, 620
  166. ^ Seese & Daub 1985, p. 65
  167. ^ MacKay, MacKay & Henderson 2002, pp. 209, 211
  168. ^ Cousins, Davidson & García-Vivó 2013, pp. 11809–11811
  169. ^ a b Cao et al. 2021, p. 4
  170. ^ Liptrot 1983, p. 161; Malone & Dolter 2008, p. 255
  171. ^ Wiberg 2001, pp. 255–257
  172. ^ Scott & Kanda 1962, p. 153
  173. ^ Taylor 1960, p. 316
  174. ^ a b c d Emsley 2011, passim
  175. ^ Crawford 1968, p. 540; Benner, Ricardo & Carrigan 2018, pp. 167–168: "The stability of the carbon-carbon bond ... has made it the first choice element to scaffold biomolecules. Hydrogen is needed 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."
  176. ^ Zhao, Tu & Chan 2021
  177. ^ Kosanke et al. 2012, p. 841
  178. ^ Wasewar 2021, pp. 322–323
  179. ^ Messler 2011, p. 10
  180. ^ King et al. 1994, p. 1344; Powell & Tims 1974, pp. 189–191; Cao et al. 2021, pp. 20–21
  181. ^ Vernon 2020, pp. 221–223; Rayner-Canham 2020, p. 216
  182. ^ National Center for Biotechnology Information 2021
  183. ^ Emsley 2011, p. 113
  184. ^ Greenwood & Earnshaw 2002, p. 270–271
  185. ^ Khan 2001, p. 59
  186. ^ Emsley 2011, pp. 376, 380, 640
  187. ^ Cox 1997, pp. 130; Emsley 2011, p. 393
  188. ^ Cox 1997, pp. 130; Emsley 2011, pp. 515–516, 518
  189. ^ Boyd 2011, p. 570
  190. ^ Chandra X-ray Center 2018
  191. ^ a b c Nelson 1987, p. 732
  192. ^ Fortescue 2012, pp. 56, 65
  193. ^ Ostriker & Steinhardt 2001, pp. 46‒53; Zhu 2020, p. 27
  194. ^ Cox 1997, pp. 17–19
  195. ^ Steudel 2020, p. v
  196. ^ a b c Allcock 2020, pp. 61–63; Emsley 2011, passim; Harbison, Bourgeois & Johnson 2015, p. 364; USGS Mineral Commodity Summaries 2023
  197. ^ Burke 2020, p. 262; Csele 2016; Imberti & Sadler 2020, p. 8
  198. ^ Kiiski et al. 2016; King 2019, p. 408
  199. ^ Beard et al. 2021; Bhuwalka et al. 2021, pp. 10097–10107; Bolin 2017, p. 2-1; Reinhardt at al. 2015
  200. ^ Allcock 2020, pp. 61–63; Emsley 2011, passim; Gaffney & Marley 2017, p. 23; USGS Mineral Commodity Summaries 2023
  201. ^ Whitten et al. 2014, p. 133
  202. ^ Ward 2010, p. 250
  203. ^ Weeks ME & Leicester 1968, p. 550
  204. ^ Zhong & Nsengiyumva, p. 19
  205. ^ Angelo & Ravisankar p. 56–57
  206. ^ Greenwood & Earnshaw 2002, p. 482
  207. ^ Sultana et al. 2022
  208. ^ Haller 2006, p. 3
  209. ^ Shanks et al. 2017, pp. I2–I3
  210. ^ Emsley 2011, p. 611
  211. ^ Baja, Cascella & Borger 2022; Webb-Mack 2019
  212. ^ Rodgers 2012, p. 571
  213. ^ Greger 2023
  214. ^ Pawlicki, Scanderbeg & Starkschall 2016, p. 228
  215. ^ Labinger 2019, p. 305
  216. ^ Emsley 2011, pp. 42–43, 219–220, 263–264, 341, 441–442, 596, 609
  217. ^ Toon 2011
  218. ^ Emsley 2011, pp. 84, 128, 180–181, 247
  219. ^ Cook 1923, p. 124
  220. ^ Weeks ME & Leicester 1968, p. 309
  221. ^ Emsley 2011, pp. 113, 363, 378, 477, 514–515
  222. ^ Weeks & Leicester 1968, pp. 95, 97, 103
  223. ^ Lavoisier 1790, p. 175
  224. ^ Jordan 2016
  225. ^ Stillman 1924, p. 213
  226. ^ de L'Aunay 1566, p. 7
  227. ^ Lémery 1699, p. 118; Dejonghe 1998, p. 329
  228. ^ Strathern 2000, p. 239
  229. ^ Criswell p. 1140
  230. ^ Salzberg 1991, p. 204
  231. ^ Berzelius 1811, p. 258
  232. ^ Partington 1964, p. 168
  233. ^ a b Bache 1832, p. 250
  234. ^ Goldsmith 1982, p. 526
  235. ^ Roscoe & Schormlemmer 1894, p. 4
  236. ^ Glinka 1959, p. 76
  237. ^ Hérold 2006, pp. 149–150
  238. ^ a b c The Chemical News and Journal of Physical Science 1864
  239. ^ Oxford University Press 1989
  240. ^ Kemshead 1875, p. 13
  241. ^ Kendall 1811, pp. 298–303
  242. ^ Brande 1821, p. 5
  243. ^ Herzfeld 1927; Edwards 2000, pp. 100–03
  244. ^ Edwards & Sienko 1983, p. 693
  245. ^ Kubaschewski 1949, pp. 931–940
  246. ^ Remy 1956, p. 9
  247. ^ White 1962, p. 106: It makes a ringing sound when struck.
  248. ^ Johnson 1966, pp. 3–4
  249. ^ Horvath 1973, pp. 335–336
  250. ^ Myers 1979, p. 712
  251. ^ Rao & Ganguly 1986
  252. ^ Smith & Dwyer 1991, p. 65: The difference between melting point and boiling point.
  253. ^ a b Herman 1999, p. 702
  254. ^ Suresh & Koga 2001, pp. 5940–5944
  255. ^ a b Edwards 2010, pp. 941–965
  256. ^ Hill, Holman & Hulme 2017, p. 182: Atomic conductance is the electrical conductivity of one mole of a substance. It is equal to electrical conductivity divided by molar volume.
  257. ^ Povh & Rosin 2017, p. 131
  258. ^ Beach 1911
  259. ^ Stott 1956, pp. 100–102
  260. ^ Parish 1977, p. 178
  261. ^ Sanderson 1957, p. 229
  262. ^ Hare & Bache 1836, p. 310
  263. ^ Chambers 1743: "That which distinguishes metals from all other bodies ... is their heaviness ..."
  264. ^ Erman and Simon 1808
  265. ^ Hare 1836, p. 310
  266. ^ Edwards 2000, p. 85
  267. ^ Russell & Lee 2005, p. 466
  268. ^ Atkins et al. 2006, pp. 320–21
  269. ^ Zhigal'skii & Jones 2003, p. 66
  270. ^ Kneen, Rogers & Simpson 1972, pp. 218–219
  271. ^ Emsley 1971, p. 1
  272. ^ Jones 2010, p. 169
  273. ^ a b Johnson 1966, pp. 3–6, 15
  274. ^ Shkol'nikov 2010, p. 2127
  275. ^ Aylward & Findlay 2008, pp. 6–13; 126
  276. ^ Edelstein & Morrs 2009, p. 123
  277. ^ Arblaster JW (ed.) 2018, p. 269; Lavrukhina & Pozdnyakov 1970, p. 269
  278. ^ Duffus 2002, p. 798
  279. ^ a b Rahm, Zeng & Hoffmann 2019, p. 345
  280. ^ Hein & Arena 2011, pp. 228, 523; Timberlake 1996, pp. 88, 142; Kneen, Rogers & Simpson 1972, p. 263; Baker 1962, pp. 21, 194; Moeller 1958, pp. 11, 178
  281. ^ Goldwhite & Spielman 1984, p. 130
  282. ^ Oderberg 2007, p. 97
  283. ^ Bertomeu-Sánchez, Garcia-Belmar & Bensaude-Vincent 2002, pp. 248–249
  284. ^ Dupasquier 1844, pp. 66–67
  285. ^ Bache 1832, pp. 248–276
  286. ^ Renouf 1901, pp. 268
  287. ^ Vernon 2020, pp. 217–225
  288. ^ a b Welcher 2009, p. 3–32: "The elements change from ... metalloids, to moderately active nonmetals, to very active nonmetals, and to a noble gas."
  289. ^ Vernon 2020, pp. 224
  290. ^ MacKay, MacKay & Henderson 2002, pp. 195–196
  291. ^ Bynum, Browne & Porter 1981, p. 318
  292. ^ Tregarthen 2003, p. 10
  293. ^ Lewis 1993, pp. 28, 827
  294. ^ Lewis 1993, pp. 28, 813
  295. ^ a b c Rochow 1966, p. 4
  296. ^ Wiberg 2001, p. 780; Emsley 2011, p. 397; Rochow 1966, pp. 23, 84
  297. ^ Kneen, Rogers & Simpson 1972, pp. 321, 404, 436
  298. ^ Kneen, Rogers & Simpson 1972, p. 439
  299. ^ Kneen, Rogers & Simpson 1972, p. 465
  300. ^ Kneen, Rogers & Simpson 1972, p. 308
  301. ^ Wiberg 2001, pp. 505, 681, 781; Glinka 1958, p. 355
  302. ^ Godfrin & Lauter 1995, pp. 216‒218
  303. ^ Wiberg 2001, p. 416
  304. ^ Desai, James & Ho 1984, p. 1160; Matula 1979, p. 1260
  305. ^ Schaefer 1968, p. 76; Carapella 1968, pp. 29‒32
  306. ^ Keeler & Wothers 2013, p. 293
  307. ^ Kneen, Rogers & Simpson 1972, p. 264
  308. ^ Rayner-Canham 2018, p. 203
  309. ^ Mackin 2014, p. 80
  310. ^ Johnson 1966, pp. 105–108
  311. ^ Stein 1969, pp. 5396‒5397; Pitzer 1975, pp. 760‒761
  312. ^ Porterfield 1993, p. 336
  313. ^ Rochow 1966, p. 4; Atkins et al. 2006, pp. 8, 122–123
  314. ^ Wiberg 2001, p. 750
  315. ^ Sanderson 1967, p. 172; Mingos 2019, p. 27
  316. ^ House 2008, p. 441
  317. ^ Mingos 2019, p. 27; Sanderson 1967, p. 172
  318. ^ Wiberg 2001, p. 399
  319. ^ Kläning & Appelman 1988, p. 3760
  320. ^ a b Rao 2002, p. 22
  321. ^ Sidorov 1960, pp. 599‒603
  322. ^ McMillan 2006, p. 823
  323. ^ Wells 1984, p. 534
  324. ^ a b Puddephatt & Monaghan 1989, p. 59
  325. ^ King 1995, p. 182
  326. ^ Ritter 2011, p. 10
  327. ^ Yamaguchi & Shirai 1996, p. 3
  328. ^ Vernon 2020, p. 223
  329. ^ Vernon 2020, p. 220
  330. ^ Woodward et al. 1999, p. 134
  331. ^ Dalton 2019
  332. ^ Aylward & Findlay 2008, p. 132


  • Abbott D 1966, An Introduction to the Periodic Table, J. M. Dent & Sons, London
  • Allcock HR 2020, Introduction to Materials Chemistry, 2nd ed., John Wiley & Sons, Hoboken, ISBN 978-1-119-34119-2
  • Angelo PC & Ravisankar B 2019, Introduction to Steels: Processing, Properties, and Applications, CRC Press, Boca Raton, ISBN 9781138389991
  • Arblaster JW (ed.) 2018, Selected Values of the Crystallographic Properties of Elements, ASM International, Materials Park, Ohio, ISBN 978-1-62708-154-2
  • Atkins PA 2001, The Periodic Kingdom: A Journey Into the Land of the Chemical Elements, Phoenix, London, ISBN 978-1-85799-449-0
  • Atkins P, Overton T, Rourke J, Weller M & Armstrong F 2006, Shriver & Atkins' Inorganic Chemistry, 4th ed., Oxford University Press, Oxford, ISBN 0-7167-4878-9
  • 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
  • Bache AD 1832, "An essay on chemical nomenclature, prefixed to the treatise on chemistry; by J. J. Berzelius", American Journal of Science, vol. 22, pp. 248–277
  • Bailar JC et al. 1989, Chemistry, 3rd ed., Harcourt Brace Jovanovich, San Diego, ISBN 978-0-15-506456-0
  • Bajaj T, Cascella M & Borger J 2022, "Xenon", in StatPearls, StatPearls Publishing, Treasure Island, Florida, PMID 31082041, accessed 4 October 2023
  • Baker et al. PS 1962, Chemistry and You, Lyons and Carnahan, Chicago
  • Barton AFM 2021, States of Matter, States of Mind, CRC Press, Boca Raton, ISBN 978-0-7503-0418-4
  • Beach FC (ed.) 1911, The Americana: A universal reference library, vol. XIII, Mel–New, Metalloid, Scientific American Compiling Department, New York
  • Beard A, Battenberg, C & Sutker BJ 2021, "Flame retardants", in Ullmann's Encyclopedia of Industrial Chemistry, doi:10.1002/14356007.a11_123.pub2
  • 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 1811, 'Essai sur la nomenclature chimique', Journal de Physique, de Chimie, d'Histoire Naturelle, vol. LXXIII, pp. 253‒286
  • Bhuwalka et al. 2021, "Characterizing the changes in material use due to vehicle electrification", Environmental Science & Technology, vol. 55, no. 14, pp. 10097–10107, doi:10.1021/acs.est.1c00970
  • Bladel WJ 1949, Nuclear Chemistry: Notes on a Series of Lectures, Atomic Energy Commission, Oak Ridge, Tennessee
  • 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
  • Bolin P 2017, "Gas-insulated substations", in McDonald JD (ed.), Electric Power Substations Engineering, 3rd, ed., CRC Press, Boca Raton, FL, ISBN 978-1-4398-5638-3
  • Boreskov GK 2003, Heterogeneous Catalysis, Nova Science, New York, ISBN 978-1-59033-864-3
  • Borg RG & Dienes GJ 1992, The Physical Chemistry of Solids, Academic Press, Boston, ISBN 978-0-12-118420-9
  • Boyd R 2011, "Selenium stories", Nature Chemistry, vol. 3, doi:10.1038/nchem.1076
  • Brady JE & Senese F 2009, Chemistry: The study of Matter and its Changes, 5th ed., John Wiley & Sons, New York, ISBN 978-0-470-57642-7
  • Brande WT 1821, A Manual of Chemistry, vol. II, John Murray, London
  • 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 (eds.), From atoms to polymers: isoelectronic analogies, VCH, New York, ISBN 978-0-89573-711-3
  • Burke RA 2020, Hazmatology: The Science of Hazardous Materials, Vol. 3: Applied Chemistry and Physics, CRC Press, Boca Raton, ISBN 978-1-138-31652-2
  • Burrows et al. 2021, Chemistry3: Introducing Inorganic, Organic and Physical Chemistry, 4th ed., Oxford University Press, Oxford, ISBN 978-0-19-882998-0
  • Bynum WF, Browne J & Porter R 1981 (eds), Dictionary of the History of Science, Princeton University Press, Princeton, ISBN 978-0-691-08287-5
  • Cahn RW & Haasen P, Physical Metallurgy: Vol. 1 4th ed., Elsevier Science, Amsterdam, ISBN 978-0-444-89875-3
  • 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
  • Carmalt CJ & Norman NC 1998, "Arsenic, antimony and bismuth: Some general properties and aspects of periodicity", in Norman NC (ed.), Chemistry of Arsenic, Antimony and Bismuth, Blackie Academic & Professional, London, pp. 1–38, ISBN 0-7514-0389-X
  • Carrasco et al. 2023, "Antimonene: a tuneable post-graphene material for advanced applications in optoelectronics, catalysis, energy and biomedicine", Chemical Society Reviews, vol. 52, no. 4, p. 1288–1330, doi:10.1039/d2cs00570k
  • 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 E 1743, in "Metal", Cyclopedia: Or an Universal Dictionary of Arts and Sciences (etc.), vol. 2, D Midwinter, London
  • Chambers C & Holliday AK 1982, Inorganic Chemistry, Butterworth & Co., London, ISBN 978-0-408-10822-5
  • Chandra X-ray Observatory 2018, Abundance Pie Chart, accessed 26 October 2023
  • Charlier J-C, Gonze X, Michenaud J-P 1994, "First-principles study of the stacking effect on the electronic properties of graphite(s)", Carbon, vol. 32, no. 2, pp. 289–99, doi:10.1016/0008-6223(94)90192-9
  • Chemical Abstracts Service 2021, CAS REGISTRY database as of November 2, Case #01271182
  • Chen L 2020, Painless Chemistry, 3rd ed., Kaplan, New York, ISBN 978-1-5062-6808-8
  • 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
  • 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
  • Criswell B 2007, "Mistake of having students be Mendeleev for just a day", Journal of Chemical Education, vol. 84, no. 7, pp. 1140–1144, doi:10.1021/ed084p1140
  • 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
  • de L'Aunay L 1566, Responce au discours de maistre Iacques Grevin, docteur de Paris, qu'il a escript contre le livre de maistre Loys de l'Aunay, medecin en la Rochelle, touchant la faculté de l'antimoine (Response to the Speech of Master Jacques Grévin,... Which He Wrote Against the Book of Master Loys de L'Aunay,... Touching the Faculty of Antimony), De l'Imprimerie de Barthelemi Berton, La Rochelle
  • DeKock RL & Gray HB 1989, Chemical structure and bonding, University Science Books, Mill Valley, CA, ISBN 978-0-935702-61-3
  • Dejonghe L 1998, "Zinc–lead deposits of Belgium", Ore Geology Reviews, vol. 12, no. 5, 329–354, doi:10.1016/s0169-1368(98)00007-9
  • 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 A 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
  • Dorsey MG 2023, Holding Their Breath: How the Allies Confronted the Threat of Chemical Warfare in World War II, Cornell University Press, Ithaca, New York, pp. 12-13, ISBN 978-1-5017-6837-8
  • Du Y, Ouyang C, Shi S & Lei M 2010, "Ab initio studies on atomic and electronic structures of black phosphorus", Journal of Applied Physics, vol. 107, no. 9, pp. 093718–1–4, doi:10.1063/1.3386509
  • Duffus JH 2002, " 'Heavy metals'—A meaningless term?", Pure and Applied Chemistry, vol. 74, no. 5, pp. 793–807, doi:10.1351/pac200274050793
  • Dupasquier A 1844, Traité élémentaire de chimie industrielle, Charles Savy Juene, Lyon
  • Eagleson M 1994, Concise Encyclopedia Chemistry, Walter de Gruyter, Berlin, ISBN 3-11-011451-8
  • Earl B & Wilford D 2021, Cambridge O Level Chemistry, Hodder Education, London, ISBN 978-1-3983-1059-9
  • Edelstein NM & Morrs LR 2009, "Chemistry of the actinide elements", in Nagy S (ed.), Radiochemistry and Nuclear Chemistry: Volume II, Encyclopedia of Life Support Systems, EOLSS Publishers, Oxford, pp. 118–176, ISBN 978-1-84826-577-6
  • Edwards PP 2000, "What, why and when is a metal?", in Hall N (ed.), The New Chemistry, Cambridge University, Cambridge, pp. 85–114, 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
  • Elliot A 1929, "The absorption band spectrum of chlorine", Proceedings of the Royal Society A, vol. 123, no. 792, pp. 629–644, doi:10.1098/rspa.1929.0088
  • 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, 1956
  • Encyclopaedia Britannica, 2021, Periodic table, accessed September 21, 2021
  • Engesser TA & Krossing I 2013, "Recent advances in the syntheses of homopolyatomic cations of the non metallic elements C, N, P, S, Cl, Br, I and Xe", Coordination Chemistry Reviews, vol. 257, nos. 5-6, pp. 946–955, doi:10.1016/j.ccr.2012.07.025
  • Erman P & Simon P 1808, "Third report of Prof. Erman and State Architect Simon on their joint experiments", Annalen der Physik, vol. 28, no. 3, pp. 347–367
  • Evans RC 1966, An Introduction to Crystal Chemistry, 2nd ed., Cambridge University, Cambridge
  • 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
  • Fearnside K, Jones EW & Shaw EN 1944, Applied Atomic Energy, Philosophical Library, New York
  • Fernelius WC 1982, "Polonium", Journal of Chemical Education, vol. 59, no. 9, pp. 741–42, doi:10.1021/ed059p741
  • Florez et al. 2022, "From the gas phase to the solid state: The chemical bonding in the superheavy element flerovium", The Journal of Chemical Physics, vol. 157, 064304, doi:10.1063/5.0097642
  • Fortescue JAC 2012, Environmental Geochemistry: A Holistic Approach, Springer-Verlag, New York, ISBN 978-1-4612-6047-9
  • Fox M 2010, Optical Properties of Solids, 2nd ed., Oxford University Press, New York, ISBN 978-0-19-957336-3
  • 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
  • Furse AJ & Rendle G 1975, The Pattern of Chemistry, Edward Arnold, London, ISBN 978-0-7131-1988-6
  • 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
  • Gervasini A 2013, "Characterization of acid–base sites in oxides", in Auroux A (ed.), Calorimetry and Thermal Methods in Catalysis, Springer Science, Heidelberg, pp. 319–352, doi:10.1007/978-3-642-11954-5
  • Glinka N 1958, General chemistry, Sobolev D (trans.), Foreign Languages Publishing House, Moscow
  • Glinka N 1959, General chemistry, Foreign Languages Publishing House, Moscow
  • Glinka N 1965, General Chemistry, trans. D Sobolev, Gordon & Breach, New York
  • Glinka N 1973, Problems in General Chemistry, Mir Publishers, Moscow
  • 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
  • Godovikov AA & Nenasheva N 2020, Structural-chemical Systematics of Minerals, 3rd ed., Springer, Cham, Switzerland, ISBN 978-3-319-72877-3
  • Goldsmith RH 1982, "Metalloids", Journal of Chemical Education, vol. 59, no. 6, pp. 526–527, doi:10.1021/ed059p526
  • Goldwhite H & Spielman JR 1984, College Chemistry, Harcourt Brace Jovanovich, San Diego, ISBN 978-0-15-601561-5
  • 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 & Earnshaw A 2002, Chemistry of the Elements, 2nd ed., Butterworth-Heinemann, ISBN 978-0-7506-3365-9
  • Gregersen E 2008, "Radon", in Encyclopedia Britannica, July 3, accessed 5 October 2023
  • Grochala W 2018, "On the position of helium and neon in the Periodic Table of Elements", Foundations of Chemistry, vol. 20, pp. 191–207, doi:10.1007/s10698-017-9302-7
  • Haller EE 2006, "Germanium: From its discovery to SiGe devices", Materials Science in Semiconductor Processing, vol. 9, nos 4–5, viewed 9 October 2013
  • Hamm DI 1969, Fundamental Concepts of Chemistry, Meredith Corporation, New York, ISBN 0-390-40651-1
  • Hampel CA & Hawley GG 1976, Glossary of Chemical Terms, Van Nostrand Reinhold, New York, ISBN 978-0-442-23238-2
  • Hanley JJ & Koga KT 2018, "Halogens in terrestrial and cosmic geochemical systems: Abundances, geochemical behaviours, and analytical methods" in The Role of Halogens in Terrestrial and Extraterrestrial Geochemical Processes: Surface, Crust, and Mantle, Harlov DE & Aranovich L (eds.), Springer, Cham, ISBN 978-3-319-61667-4
  • Harbison RD, Bourgeois MM & Johnson GT 2015, Hamilton and Hardy's Industrial Toxicology, 6th ed., John Wiley & Sons, Hoboken, ISBN 978-0-470-92973-5
  • Hare RA & Bache F 1836, Compendium of the Course of Chemical Instruction in the Medical Department of the University of Pennsylvania, 3rd ed., JG Auner, Philadelphia
  • Hein M & Arena S 2011, Foundations of College Chemistry, 13th ed., John Wiley & Sons, Hoboken, New Jersey, ISBN 978-0470-46061-0
  • 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
  • Henold KL & Walmsley F 1984, Chemical Principles, Properties, and Reactions, Addison Wesley, Reading, Massachusetts, ISBN 978-0-201-10422-6
  • Herman ZS 1999, "The nature of the chemical bond in metals, alloys, and intermetallic compounds, according to Linus Pauling", in Maksić, ZB, Orville-Thomas WJ (eds.), 1999, Pauling's Legacy: Modern Modelling of the Chemical Bond, Elsevier, Amsterdam, doi:10.1016/S1380-7323(99)80030-2
  • Hermann A, Hoffmann R & Ashcroft NW 2013, "Condensed astatine: Monatomic and metallic", Physical Review Letters, vol. 111, doi:10.1103/PhysRevLett.111.116404
  • Hérold A 2006, "An arrangement of the chemical elements in several classes inside the periodic table according to their common properties", Comptes Rendus Chimie, vol. 9, no. 1, doi:10.1016/j.crci.2005.10.002
  • Herzfeld K 1927, "On atomic properties which make an element a metal", Physical Review, vol. 29, no. 5, doi:10.1103/PhysRev.29.701
  • Hill G & Holman J 2000, Chemistry in Context, 5th ed., Nelson Thornes, Cheltenham, ISBN 0-17-448307-4
  • Hill G, Holman J & Hulme PG 2017, Chemistry in Context, 7th ed., Oxford University Press, Oxford, ISBN 978-0-19-839618-5
  • Holderness A & Berry M 1979, Advanced Level Inorganic Chemistry, 3rd ed., Heinemann Educational Books, London, ISBN 978-0-435-65435-1
  • Horvath AL 1973, "Critical temperature of elements and the periodic system", Journal of Chemical Education, vol. 50, no. 5, doi:10.1021/ed050p335
  • House JE 2008, Inorganic Chemistry, Elsevier, Amsterdam, ISBN 978-0-12-356786-4
  • House JE 2013, Inorganic Chemistry, 2nd ed., Elsevier, Kidlington, ISBN 978-0-12-385110-9
  • Humphrey TPJ 1908, "Systematic course of study, Chemisty and physics", Pharmaceutical Journal, vol. 80, p. 58
  • Hurlbut Jr CS 1961, Manual of Mineralogy, 15th ed., John Wiley & Sons, New York
  • Hussain et al. 2023, "Tuning the electronic properties of molybdenum di-sulphide monolayers via doping using first-principles calculations", Physica Scripta, vol. 98, no. 2, doi:10.1088/1402-4896/acacd1
  • 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
  • Janas D, Cabrero-Vilatela, A & Bulmer J 2013, "Carbon nanotube wires for high-temperature performance", Carbon, vol. 64, pp. 305–314, doi:10.1016/j.carbon.2013.07.067
  • 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
  • Jensen WB 1986, Classification, symmetry and the periodic table, Computers & Mathematics with Applications, vol. 12B, nos. 1/2, pp. 487−510, doi:10.1016/0898-1221(86)90167-7
  • 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
  • Jordan JM 2016 " 'Ancient episteme' and the nature of fossils: a correction of a modern scholarly error", History and Philosophy of the Life Sciences, vol. 38, no, 1, pp. 90–116, doi:10.1007/s40656-015-0094-6
  • Kaiho T 2017, Iodine Made Simple, CRC Press, e-book, doi:10.1201/9781315158310
  • Kaiser N 2019, "Unwrapping the periodic table", Royal Society of Chemistry, accessed 27 October 2023
  • Keeler J & Wothers P 2013, Chemical Structure and Reactivity: An Integrated Approach, Oxford University Press, Oxford, ISBN 978-0-19-960413-5
  • Kemshead WB 1875, Inorganic chemistry, William Collins, Sons, & Company, London
  • Kendall EA 1811, Pocket Encyclopædia, 2nd ed., vol. III, Longman, Hurst, Rees, Orme, and Co., London
  • Kernion MC & Mascetta JA 2019, Chemistry: The Easy Way, 6th ed., Kaplan, New York, ISBN 978-1-4380-1210-0
  • Khan N 2001, An Introduction to Physical Geography, Concept Publishing, New Delhi, ISBN 978-81-7022-898-1
  • Kiiski et al. 2016, "Fertilizers, 1. General", in Ullmann's Encyclopedia of Industrial Chemistry, doi:10.1002/14356007.a10_323.pub4
  • King AH 2019, "Our elemental footprint", Nature Materials, vol. 18, doi:10.1038/s41563-019-0334-3
  • King RB 1994, Encyclopedia of Inorganic Chemistry, vol. 3, John Wiley & Sons, New York, ISBN 978-0-471-93620-6
  • King RB 1995, Inorganic Chemistry of Main Group Elements, VCH, New York, ISBN 978-1-56081-679-9
  • King GB & Caldwell WE 1954, The Fundamentals of College Chemistry, American Book Company, New York
  • Kläning UK & Appelman EH 1988, "Protolytic properties of perxenic acid", Inorganic Chemistry, vol. 27, no. 21, doi:10.1021/ic00294a018
  • Kleinberg J 1950, "Unfamiliar oxidation states and their stabilization", Journal of Chemical Education, vol. 27, no. 1, doi:10.1021/ed027p32
  • 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
  • Koenig SH 1962, in Proceedings of the International Conference on the Physics of Semiconductors, held at Exeter, July 16–20, 1962, The Institute of Physics and the Physical Society, London
  • Kosanke et al. 2012, Encyclopedic Dictionary of Pyrotechnics (and Related Subjects), Part 3 – P to Z, Pyrotechnic Reference Series No. 5, Journal of Pyrotechnics, Whitewater, Colorado, ISBN 978-1-889526-21-8
  • 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
  • Kugler HK & Keller C (eds) 1985, Gmelin Handbook of Inorganic and Organometallic chemistry, 8th ed., "At, Astatine", system no. 8a, Springer-Verlag, Berlin, ISBN 3-540-93516-9
  • 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
  • Langley RH & Hattori H 2014, 1,001 Practice Problems: Chemistry For Dummies, John Wiley & Sons, Hoboken, NJ, ISBN 978-1-118-54932-2
  • Larrañaga MD, Lewis RJ & Lewis RA 2016, Hawley's Condensed Chemical Dictionary, 16th ed., Wiley, Hoboken, New York, ISBN 978-1-118-13515-0
  • Lavoisier A 1790, Elements of Chemistry, R Kerr (trans.), William Creech, Edinburgh
  • Lavrukhina AK & Pozdnyakov AA 1970, Analytical Chemistry of Technetium, Promethium, Astatine, and Francium, R Kondor, trans., Ann Arbor–Humphrey Science Publishers, Ann Arbor, ISBN 978-0-250-39923-9
  • Lee JD 1996, Concise Inorganic Chemistry, 5th ed., Blackwell Science, Oxford, ISBN 978-0-632-05293-6
  • Lee KKM & Steinle-Neumann G 2006, "High-pressure alloying of iron and xenon: “Missing” Xe in the Earth’s core?", Journal of Geophysical Research: Solid Earth, vol. 111, no. B2, doi:10.1029/2005jb003781
  • Lémery N 1714, Traité universel des drogues simples, mises en ordre alphabetique, L d'Houry, Paris, p. 118
  • Lewis RJ 1993, Hawley's Condensed Chemical Dictionary, 12th ed., Van Nostrand Reinhold, New York, ISBN 978-0-442-01131-4
  • Lewis RS & Deen WM 1994, "Kinetics of the reaction of nitric oxide with oxygen in aqueous solutions", Chemical Research in Toxicology, vol. 7, no. 4, pp. 568–574, doi:10.1021/tx00040a013
  • Liptrot GF 1983, Modern Inorganic Chemistry, 4th ed., Bell & Hyman, ISBN 978-0-7135-1357-8
  • Liu J, Yang Y, Zheng X 2022, "The fundamentals of metal oxides for electrocatalytic water splitting," in Qi J (ed.), Metal Oxides and Related Solids for Electrocatalytic Water Splitting, Elsevier, Amsterdam, pp. 25–60, ISBN 978-0-323-85735-2
  • Los Alamos National Laboratory 2021, Periodic Table of Elements: A Resource for Elementary, Middle School, and High School Students, accessed September 19, 2021
  • 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
  • Malone LJ & Dolter T 2008, Basic Concepts of Chemistry, 8th ed., John Wiley & Sons, Hoboken, ISBN 978-0-471-74154-1
  • 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
  • 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
  • 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 1958, Qualitative Analysis: An Introduction to Equilibrium and Solution Chemistry, McGraw-Hill, New York
  • 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
  • Morita A 1986, "Semiconducting black phosphorus", Journal of Applied Physics A, vol. 39, no. 4, pp. 227–42, doi:10.1007/BF00617267
  • Morely HF & Muir MM 1892, Watt's Dictionary of Chemistry, vol. 3, Longman's Green, and Co., London
  • Moss, TS 1952, Photoconductivity in the Elements, Butterworths Scientific, London
  • Myers RT 1979, "Physical and chemical properties and bonding of metallic elements", Journal of Chemical Education, vol. 56, no. 11, pp. 712–73, doi:10.1021/ed056p71
  • 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
  • Nefedov VD et al. 1968, 'Astatine', Russian Chemical Reviews, vol. 37, no. 2, pp. 87–98, doi:10.1070/rc1968v037n02abeh0
  • 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
  • Ostriker JP & Steinhardt PJ 2001, "The quintessential universe", Scientific American, vol. 284, no. 1, pp. 46–53 PMID 11132422, doi:10.1038/scientificamerican0101-46
  • Oxford University Press 1989, "nonmetal", Oxford English Dictionary
  • 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
  • Parkes GD & Mellor JW 1943, Mellor's Modern Inorganic Chemistry, Longmans, Green and Co., London
  • Partington JR 1944, A Text-book of Inorganic Chemistry, 5th ed., Macmillan & Co., London
  • Partington JR 1964, A history of chemistry, vol. 4, Macmillan, London
  • Pascoe KJ 1982, An Introduction to the Properties of Engineering Materials, 3rd ed., Von Nostrand Reinhold (UK), Wokingham, Berkshire, ISBN 978-0-442-30233-7
  • Pawlicki T, Scanderbeg DJ & Starkschall G 2016, Hendee's Radiation Therapy Physics, 4th ed., John Wiley & Sons, Hoboken, NJ, p. 228, ISBN 978-0-470-37651-5
  • Petruševski VM & Cvetković J 2018, "On the 'true position' of hydrogen in the Periodic Table", Foundations of Chemistry, vol. 20, pp. 251–260, doi:10.1007/s10698-018-9306-y
  • Phillips CSG & Williams RJP 1965, Inorganic Chemistry, vol. 1, Principles and non-metals, Clarendon Press, Oxford
  • Phillips JC 1973, "The chemical structure of solids", in Hannay NB (ed.), Treatise on Solid State Chemistry, vol. 1, Plenum Press, New York, pp. 1–42, ISBN 978-1-4684-2663-2
  • 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
  • Radon, Royal Society of Chemistry, accessed 3 October 2023
  • Rahm M, Zeng T & Hoffmann R 2019, "Electronegativity seen as the ground-state average valence electron binding energy", Journal of the American Chemical Society, vol. 141, no. 1, pp. 342–351, doi:10.1021/jacs.8b10246
  • 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 (Ed's.) Mendeleev to Oganesson: A multidisciplinary perspective on the periodic table, Oxford University, New York, ISBN 978-0-190-668532
  • Rayner-Canham G 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
  • Reinhardt et al. 2015, Inerting in the chemical industry, Linde, Pullach, Germany, accessed October 19 2021
  • Remy H 1956, Treatise on Inorganic Chemistry, Anderson JS (trans.), Kleinberg J (ed.), vol. II, Elsevier, Amsterdam
  • Renouf E 1901, "Lehrbuch der Anorganischen Chemie", Science, vol. 13, no. 320, doi:10.1126/science.13.320.268
  • Restrepo G, Llanos EJ & Mesa H 2006, "Topological space of the chemical elements and its properties", Journal of Mathematical Chemistry, vol. 39, doi:10.1007/s10910-005-9041-1
  • Ritchie R 2004, Revive A2 Chemistry, Letts Educational, London, ISBN 978-1-84315-438-9
  • 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
  • Rodgers GE 2012, Descriptive Inorganic, Coordination, and Solid State Chemistry, 3rd ed., Brooks/Cole, Belmont, California, ISBN 978-0-8400-6846-0
  • Roscoe HE & Schorlemmer FRS 1894, A treatise on chemistry: Volume II: The metals, D Appleton, New York
  • Royal Society of Chemistry 2021, Periodic Table: Non-metal, accessed September 3, 2021
  • Rudakiya DM & Patel Y 2021, "Bioremediation of metals, metalloids, and nonmetals", in Panpatte DG & Jhala YK (eds), Microbial Rejuvenation of Polluted Environment, vol. 2, Springer Nature, Singapore, pp. 33–49, doi:10.1007/978-981-15-7455-9_2
  • 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
  • Salinas JT 2019 Exploring Physical Science in the Laboratory, Moreton Publishing, Englewood, Colorado, ISBN 978-1-61731-753-8
  • 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
  • Scerri E 2020, The Periodic Table: Its Story and Its Significance, Oxford University Press, New York, ISBN 978-0-19091-436-3
  • Schaefer JC 1968, "Boron" in Hampel CA (ed.), The Encyclopedia of the Chemical Elements, Reinhold, New York
  • 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
  • Scott D 2014, 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 1948, "The eight new synthetic elements", American Scientist, vol. 36, no. 3, p. 368
  • Seese WS & Daub GH 1985, Basic Chemistry, 4th ed., Prentice-Hall, Englewood Cliffs, NJ, ISBN 978-0-13-057811-2
  • Segal BG 1989, Chemistry: Experiment and Theory, 2nd ed., John Wiley & Sons, New York, ISBN 0-471-84929-4
  • 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
  • Shang et al. 2021, "Ultrahard bulk amorphous carbon from collapsed fullerene", Nature, vol. 599, pp. 599–604, doi:10.1038/s41586-021-03882-9
  • Shanks III WCP et al. 2017, "Germanium and indium", in Schulz et al. (eds), Critical Mineral Resources of the United States: Economic and Environmental Geology and Prospects for Future Supply, U.S. Geological Survey, Reston, Virginia, ISBN 978-1-4113-3991-0
  • Shkol’nikov EV 2010, "Thermodynamic characterization of the amphoterism of oxides M2O3 (M = As, Sb, Bi) and their hydrates in aqueous media, Russian Journal of Applied Chemistry, vol. 83, no. 12, pp. 2121–2127, doi:10.1134/S1070427210120104
  • 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 2020, Chemistry of the Non-metals: Syntheses – Structures – Bonding – Applications, in collaboration with D Scheschkewitz, Berlin, Walter de Gruyter, doi:10.1515/9783110578065
  • Still B 2016 The Secret Life of the Periodic Table, Cassell, London, ISBN 978-1-84403-885-5
  • Stillman JM 1924, The Story of Early Chemistry, D. Appleton, New York
  • Stott RWA 1956, Companion to Physical and Inorganic Chemistry, Longmans, Green and Co, London
  • Stuke J 1974, "Optical and electrical properties of selenium", in Zingaro RA & Cooper WC (eds.), Selenium, Van Nostrand Reinhold, New York, pp. 174
  • Strathern P 2000, Mendeleyev's dream: The Quest for the Elements, Hamish Hamilton, London, ISBN 978-0-8412-1786-7
  • Sultana et al. 2022, "Synthesis, modification, and application of black phosphorus, few-layer black phosphorus (FLBP), and phosphorene: a detailed review", Materials Advances, vol. 3, no. 14, pp. 5557–5574, doi:10.1039/D1MA01101D
  • Suresh CH & Koga NA 2001, "A consistent approach toward atomic radii”, Journal of Physical Chemistry A, vol. 105, no. 24. doi:10.1021/jp010432b
  • Tang et al. 2021, "Synthesis of paracrystalline diamond", Nature, vol. 599, pp. 605–610, doi:10.1038/s41586-021-04122-w
  • Taniguchi M, Suga S, Seki M, Sakamoto H, Kanzaki H, Akahama Y, Endo S, Terada S & Narita S 1984, "Core-exciton induced resonant photoemission in the covalent semiconductor black phosphorus", Solid State Communications, vo1. 49, no. 9, pp. 867–7, doi:10.1016/0038-1098(84)90441-1
  • 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
  • Thompson M 2004, "Osmium tetroxide (OsO4)", Molecule of the Month, (May), doi:10.6084/m9.figshare.5437084
  • Thornton BF & Burdette SC 2010, "Finding eka-iodine: Discovery priority in modern times", Bulletin for the history of chemistry, vol. 35, no. 2, accessed September 14, 2021
  • Tidy CM 1887, Handbook of Modern Chemistry, 2nd ed., Smith, Elder & Co., London
  • Timberlake KC 1996, Chemistry: An Introduction to General, Organic, and Biological Chemistry, 6th ed., HarperCollinsCollege, ISBN 978-0-673-99054-9
  • Toon R 2011, "The discovery of fluorine", Education in Chemistry, Royal Society of Chemistry, accessed 7 October 2023
  • 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
  • U.S. Geological Survey 2023, Mineral Commodity Summaries, U.S. Geological Survey, accessed 3 October 2023
  • Vallabhajosula S 2023, Molecular Imaging and Targeted Therapy: Radiopharmaceuticals and Clinical Applications, 2nd ed., Springer Nature, Cham, Switzerland, ISBN 978-3-031-23203-9
  • Vasáros L & Berei K 1985, "General properties of astatine", pp. 107–28, in Kugler & Keller
  • 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 (open access)
  • 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
  • Ward D 2010, "What Is the diversity of life in the cosmos?" in Lynden-Bell et al. (eds), Water and Life: The Unique Properties of H2O, CRC Press, Boca Raton, ISBN 978-0-429-19103-9
  • Wasewar KL 2021, "Intensifying approaches for removal of selenium", in Devi et al. (eds.), Selenium contamination in water, John Wiley & Sons, Hoboken, pp. 319–355, ISBN 978-1-119-69354-3
  • Webb-Mack 2019, A Brief History of Ion Propulsion, NASA, accessed 5 October 2023
  • Weeks ME & Leicester HM 1968, Discovery of the Elements, 7th ed., Journal of Chemical Education, Easton, Pennsylvania
  • Welcher SH 2009, High marks: Regents Chemistry Made Easy, 2nd ed., High Marks Made Easy, New York, ISBN 978-0-9714662-0-3
  • Wells AF 1984, Structural Inorganic Chemistry, 5th ed., Clarendon Press, Oxford, ISBN 978-0-19-855370-0
  • White JH 1962, Inorganic Chemistry: Advanced and Scholarship Levels, University of London Press, London
  • Whitten et al. 2014, Chemistry, 10th ed., Brooks Cole, Belmont CA, ISBN 978-1-133-61066-3
  • Wibaut P 1951, Organic Chemistry, Elsevier Publishing Company, New York
  • Wiberg N 2001, Inorganic Chemistry, Academic Press, San Diego, ISBN 978-0-12-352651-9
  • 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
  • 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 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
  • Yang J 2004, "Theory of thermal conductivity", in Tritt TM (ed.), Thermal Conductivity: Theory, Properties, and Applications, Kluwer Academic/Plenum Publishers, New York, pp. 1–20, ISBN 978-0-306-48327-1,
  • Yoder CH, Suydam FH & Snavely FA 1975, Chemistry, 2nd ed, Harcourt Brace Jovanovich, New York, ISBN 978-0-15-506470-6
  • Young JA 2006, "Iodine", Journal of Chemical Education, vol. 83, no. 9, doi:10.1021/ed083p1285
  • Young et al. 2018, General Chemistry: Atoms First, Cengage Learning: Boston, ISBN 978-1-337-61229-6
  • Zhao J, Tu Z & Chan SH 2021, "Carbon corrosion mechanism and mitigation strategies in a proton exchange membrane fuel cell (PEMFC): A review", Journal of Power Sources, vol. 488, #229434, doi:10.1016/j.jpowsour.2020.229434
  • Zhigal'skii GP & Jones BK 2003, The Physical Properties of Thin Metal Films, Taylor & Francis, London, ISBN 978-0-415-28390-8
  • Zhong S & Nsengiyumva W 2022, "Nondestructive Testing and Evaluation of Fiber-Reinforced Composite Structures", Science Press, Singapore, ISBN 978-981-19-0848-4
  • Zhu W 2020, Chemical Elements In Life, World Scientific, Singapore, ISBN 978-981-121-032-7
  • 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
  • Zumdahl SS & DeCoste DJ 2010, Introductory Chemistry: A Foundation, 7th ed., Cengage Learning, Mason, Ohio, ISBN 978-1-111-29601-8

External links[edit]

  • Media related to Nonmetals at Wikimedia Commons