chemistry
Chemistry is the scientific study of the properties and behavior of matter. It is a natural science that covers the elements that make up matter to the compounds made of atoms, molecules and ions: their composition, structure, proper ...
, a nonmetal is a
chemical element
A chemical element is a species of atoms that have a given number of protons in their atomic nucleus, nuclei, including the pure Chemical substance, substance consisting only of that species. Unlike chemical compounds, chemical elements canno ...
that generally lacks a predominance of
metal
A metal (from ancient Greek, Greek μέταλλον ''métallon'', "mine, quarry, metal") is a material that, when freshly prepared, polished, or fractured, shows a lustrous appearance, and conducts electrical resistivity and conductivity, e ...
lic properties; they range from colorless gases (like
hydrogen
Hydrogen is the chemical element with the symbol H and atomic number 1. Hydrogen is the lightest element. At standard conditions hydrogen is a gas of diatomic molecules having the formula . It is colorless, odorless, tasteless, non-to ...
) to shiny solids (like carbon, as
graphite
Graphite () is a crystalline form of the element carbon. It consists of stacked layers of graphene. Graphite occurs naturally and is the most stable form of carbon under standard conditions. Synthetic and natural graphite are consumed on la ...
). The
electron
The electron ( or ) is a subatomic particle with a negative one elementary electric charge. Electrons belong to the first generation of the lepton particle family,
and are generally thought to be elementary particles because they have n ...
s in nonmetals behave differently from those in metals. With some exceptions, those in nonmetals are fixed in place, resulting in nonmetals usually being poor conductors of heat and electricity and brittle or crumbly when solid. The electrons in metals are generally free moving and this is why metals are good conductors and most are easily flattened into sheets and drawn into wires. Nonmetal atoms tend to attract
electron
The electron ( or ) is a subatomic particle with a negative one elementary electric charge. Electrons belong to the first generation of the lepton particle family,
and are generally thought to be elementary particles because they have n ...
s in
chemical reaction
A chemical reaction is a process that leads to the chemical transformation of one set of chemical substances to another. Classically, chemical reactions encompass changes that only involve the positions of electrons in the forming and breaking ...
s and to form
acid
In computer science, ACID ( atomicity, consistency, isolation, durability) is a set of properties of database transactions intended to guarantee data validity despite errors, power failures, and other mishaps. In the context of databases, a se ...
ic compounds.
Two nonmetals,
hydrogen
Hydrogen is the chemical element with the symbol H and atomic number 1. Hydrogen is the lightest element. At standard conditions hydrogen is a gas of diatomic molecules having the formula . It is colorless, odorless, tasteless, non-to ...
and
helium
Helium (from el, ἥλιος, helios, lit=sun) is a chemical element with the symbol He and atomic number 2. It is a colorless, odorless, tasteless, non-toxic, inert, monatomic gas and the first in the noble gas group in the periodic ta ...
,
make up
Cosmetics are constituted mixtures of chemical compounds derived from either natural sources, or synthetically created ones. Cosmetics have various purposes. Those designed for personal care and skin care can be used to cleanse or protect ...
about 99% of ordinary
matter
In classical physics and general chemistry, matter is any substance that has mass and takes up space by having volume. All everyday objects that can be touched are ultimately composed of atoms, which are made up of interacting subatomic part ...
in the
observable universe
The observable universe is a ball-shaped region of the universe comprising all matter that can be observed from Earth or its space-based telescopes and exploratory probes at the present time, because the electromagnetic radiation from these ob ...
by mass. Five nonmetallic elements, hydrogen,
carbon
Carbon () is a chemical element with the symbol C and atomic number 6. It is nonmetallic and tetravalent—its atom making four electrons available to form covalent chemical bonds. It belongs to group 14 of the periodic table. Carbon ma ...
,
nitrogen
Nitrogen is the chemical element with the symbol N and atomic number 7. Nitrogen is a nonmetal and the lightest member of group 15 of the periodic table, often called the pnictogens. It is a common element in the universe, estimated at se ...
,
oxygen
Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements ...
and
silicon
Silicon is a chemical element with the symbol Si and atomic number 14. It is a hard, brittle crystalline solid with a blue-grey metallic luster, and is a tetravalent metalloid and semiconductor. It is a member of group 14 in the periodic ...
, largely make up the
Earth's crust
Earth's crust is Earth's thin outer shell of rock, referring to less than 1% of Earth's radius and volume. It is the top component of the lithosphere, a division of Earth's layers that includes the crust and the upper part of the mantle. The ...
,
atmosphere
An atmosphere () is a layer of gas or layers of gases that envelop a planet, and is held in place by the gravity of the planetary body. A planet retains an atmosphere when the gravity is great and the temperature of the atmosphere is low. A ...
biosphere
The biosphere (from Greek βίος ''bíos'' "life" and σφαῖρα ''sphaira'' "sphere"), also known as the ecosphere (from Greek οἶκος ''oîkos'' "environment" and σφαῖρα), is the worldwide sum of all ecosystems. It can also ...
.
Most nonmetals have biological, technological or domestic roles or uses. Living organisms are composed almost entirely of the nonmetals hydrogen, oxygen, carbon, and nitrogen. Nearly all nonmetals have individual uses in medicine and
pharmaceutical
A medication (also called medicament, medicine, pharmaceutical drug, medicinal drug or simply drug) is a drug used to diagnose, cure, treat, or prevent disease. Drug therapy ( pharmacotherapy) is an important part of the medical field and ...
s; lighting and
laser
A laser is a device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation. The word "laser" is an acronym for "light amplification by stimulated emission of radiation". The ...
s; and household items.
While the term ''non-metallic'' dates from as far back as 1566, there is no widely agreed precise definition of a nonmetal. Some elements have a marked mixture of metallic and nonmetallic properties; which of these borderline cases are counted as nonmetals can vary depending on the classification criteria. Fourteen elements are effectively always recognized as nonmetals and up to about nine more are frequently to sometimes added, as shown in the
periodic table
The periodic table, also known as the periodic table of the (chemical) elements, is a rows and columns arrangement of the chemical elements. It is widely used in chemistry, physics, and other sciences, and is generally seen as an icon of ch ...
extract.
Definition and applicable elements
A nonmetal is a
chemical element
A chemical element is a species of atoms that have a given number of protons in their atomic nucleus, nuclei, including the pure Chemical substance, substance consisting only of that species. Unlike chemical compounds, chemical elements canno ...
deemed to lack a preponderance of metallic properties such as luster, deformability, good thermal and electrical conductivity, and the capacity to form a basic (rather than acidic) oxide. Since there is no rigorous definition of a nonmetal,Godovikov & Nenasheva 2020, p. 4Sanderson 1957, p. 229 some variation exists among sources as to which elements are classified as such. The decisions involved depend on which property or properties are regarded as most indicative of nonmetallic or metallic character.Kneen, Rogers & Simpson 1972, pp. 218–219
Although Steudel, in 2020, recognised twenty-three elements as nonmetals, any such list is open to challenge. Fourteen almost always recognized are
hydrogen
Hydrogen is the chemical element with the symbol H and atomic number 1. Hydrogen is the lightest element. At standard conditions hydrogen is a gas of diatomic molecules having the formula . It is colorless, odorless, tasteless, non-to ...
,
oxygen
Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements ...
,
nitrogen
Nitrogen is the chemical element with the symbol N and atomic number 7. Nitrogen is a nonmetal and the lightest member of group 15 of the periodic table, often called the pnictogens. It is a common element in the universe, estimated at se ...
, and
sulfur
Sulfur (or sulphur in British English) is a chemical element with the symbol S and atomic number 16. It is abundant, multivalent and nonmetallic. Under normal conditions, sulfur atoms form cyclic octatomic molecules with a chemical formul ...
; the highly reactive
halogens
The halogens () are a group in the periodic table consisting of five or six chemically related elements: fluorine (F), chlorine (Cl), bromine (Br), iodine (I), astatine (At), and tennessine (Ts). In the modern IUPAC nomenclature, this group i ...
fluorine
Fluorine is a chemical element with the symbol F and atomic number 9. It is the lightest halogen and exists at standard conditions as a highly toxic, pale yellow diatomic gas. As the most electronegative reactive element, it is extremely reactiv ...
,
chlorine
Chlorine is a chemical element with the symbol Cl and atomic number 17. The second-lightest of the halogens, it appears between fluorine and bromine in the periodic table and its properties are mostly intermediate between them. Chlorine i ...
,
bromine
Bromine is a chemical element with the symbol Br and atomic number 35. It is the third-lightest element in group 17 of the periodic table ( halogens) and is a volatile red-brown liquid at room temperature that evaporates readily to form a simi ...
, and
iodine
Iodine is a chemical element with the Symbol (chemistry), symbol I and atomic number 53. The heaviest of the stable halogens, it exists as a semi-lustrous, non-metallic solid at standard conditions that melts to form a deep violet liquid at , ...
; and the
noble gases
The noble gases (historically also the inert gases; sometimes referred to as aerogens) make up a class of chemical elements with similar properties; under standard conditions, they are all odorless, colorless, monatomic gases with very low ch ...
helium
Helium (from el, ἥλιος, helios, lit=sun) is a chemical element with the symbol He and atomic number 2. It is a colorless, odorless, tasteless, non-toxic, inert, monatomic gas and the first in the noble gas group in the periodic ta ...
,
neon
Neon is a chemical element with the symbol Ne and atomic number 10. It is a noble gas. Neon is a colorless, odorless, inert monatomic gas under standard conditions, with about two-thirds the density of air. It was discovered (along with krypt ...
,
argon
Argon is a chemical element with the symbol Ar and atomic number 18. It is in group 18 of the periodic table and is a noble gas. Argon is the third-most abundant gas in Earth's atmosphere, at 0.934% (9340 ppmv). It is more than twice a ...
,
krypton
Krypton (from grc, κρυπτός, translit=kryptos 'the hidden one') is a chemical element with the symbol Kr and atomic number 36. It is a colorless, odorless, tasteless noble gas that occurs in trace amounts in the atmosphere and is of ...
,
xenon
Xenon is a chemical element with the symbol Xe and atomic number 54. It is a dense, colorless, odorless noble gas found in Earth's atmosphere in trace amounts. Although generally unreactive, it can undergo a few chemical reactions such as the ...
, and
radon
Radon is a chemical element with the symbol Rn and atomic number 86. It is a radioactive, colourless, odourless, tasteless noble gas. It occurs naturally in minute quantities as an intermediate step in the normal radioactive decay chains th ...
(see e.g. Larrañaga et al). The authors recognized
carbon
Carbon () is a chemical element with the symbol C and atomic number 6. It is nonmetallic and tetravalent—its atom making four electrons available to form covalent chemical bonds. It belongs to group 14 of the periodic table. Carbon ma ...
,
phosphorus
Phosphorus is a chemical element with the symbol P and atomic number 15. Elemental phosphorus exists in two major forms, white phosphorus and red phosphorus, but because it is highly reactive, phosphorus is never found as a free element on Ea ...
and
selenium
Selenium is a chemical element with the symbol Se and atomic number 34. It is a nonmetal (more rarely considered a metalloid) with properties that are intermediate between the elements above and below in the periodic table, sulfur and tellurium, ...
as nonmetals; Vernon had earlier reported that these three elements were instead sometimes counted as
metalloids
A metalloid is a type of chemical element which has a preponderance of properties in between, or that are a mixture of, those of metals and nonmetals. There is no standard definition of a metalloid and no complete agreement on which elements are ...
. The elements commonly recognized as
metalloids
A metalloid is a type of chemical element which has a preponderance of properties in between, or that are a mixture of, those of metals and nonmetals. There is no standard definition of a metalloid and no complete agreement on which elements are ...
namely
boron
Boron is a chemical element with the symbol B and atomic number 5. In its crystalline form it is a brittle, dark, lustrous metalloid; in its amorphous form it is a brown powder. As the lightest element of the '' boron group'' it has t ...
;
silicon
Silicon is a chemical element with the symbol Si and atomic number 14. It is a hard, brittle crystalline solid with a blue-grey metallic luster, and is a tetravalent metalloid and semiconductor. It is a member of group 14 in the periodic ...
and
germanium
Germanium is a chemical element with the symbol Ge and atomic number 32. It is lustrous, hard-brittle, grayish-white and similar in appearance to silicon. It is a metalloid in the carbon group that is chemically similar to its group neighbors ...
;
arsenic
Arsenic is a chemical element with the symbol As and atomic number 33. Arsenic occurs in many minerals, usually in combination with sulfur and metals, but also as a pure elemental crystal. Arsenic is a metalloid. It has various allotropes, b ...
and
antimony
Antimony is a chemical element with the symbol Sb (from la, stibium) and atomic number 51. A lustrous gray metalloid, it is found in nature mainly as the sulfide mineral stibnite (Sb2S3). Antimony compounds have been known since ancient ti ...
; and
tellurium
Tellurium is a chemical element with the symbol Te and atomic number 52. It is a brittle, mildly toxic, rare, silver-white metalloid. Tellurium is chemically related to selenium and sulfur, all three of which are chalcogens. It is occasionall ...
are sometimes counted as an intermediate class between the metals and the nonmetals when the criteria used to distinguish between metals and nonmetals are inconclusive. At other times they are counted as nonmetals in light of their nonmetallic chemistry.
Of the 118 known elements no more than about 20% are regarded as nonmetals. The status of a few elements is less certain.
Astatine
Astatine is a chemical element with the symbol At and atomic number 85. It is the rarest naturally occurring element in the Earth's crust, occurring only as the decay product of various heavier elements. All of astatine's isotopes are short-live ...
, the fifth halogen, is often ignored on account of its rarity and intense radioactivity; theory and experimental evidence suggest it is a metal. The superheavy elements
copernicium
Copernicium is a synthetic chemical element with the symbol Cn and atomic number 112. Its known isotopes are extremely radioactive, and have only been created in a laboratory. The most stable known isotope, copernicium-285, has a half-life of ap ...
(''Z'' = 112),
flerovium
Flerovium is a superheavy chemical element with symbol Fl and atomic number 114. It is an extremely radioactive synthetic element. It is named after the Flerov Laboratory of Nuclear Reactions of the Joint Institute for Nuclear Research in Dub ...
(114), and
oganesson
Oganesson is a synthetic chemical element with the symbol Og and atomic number 118. It was first synthesized in 2002 at the Joint Institute for Nuclear Research (JINR) in Dubna, near Moscow, Russia, by a joint team of Russian and American scient ...
(118) may turn out to be nonmetals; their status has not been confirmed.
General properties
Physical
:''Physical properties apply to elements in their most stable forms in ambient conditions''
About half of nonmetallic elements are gases; most of the rest are shiny solids.
Bromine
Bromine is a chemical element with the symbol Br and atomic number 35. It is the third-lightest element in group 17 of the periodic table ( halogens) and is a volatile red-brown liquid at room temperature that evaporates readily to form a simi ...
, the only liquid, is so volatile that it is usually topped by a layer of its fumes; sulfur is the only colored solid nonmetal. The fluid nonmetals have very low densities,
melting point
The melting point (or, rarely, liquefaction point) of a substance is the temperature at which it changes state from solid to liquid. At the melting point the solid and liquid phase exist in equilibrium. The melting point of a substance depen ...
s and
boiling point
The boiling point of a substance is the temperature at which the vapor pressure of a liquid equals the pressure surrounding the liquid and the liquid changes into a vapor.
The boiling point of a liquid varies depending upon the surrounding env ...
s, and are poor conductors of
heat
In thermodynamics, heat is defined as the form of energy crossing the boundary of a thermodynamic system by virtue of a temperature difference across the boundary. A thermodynamic system does not ''contain'' heat. Nevertheless, the term is ...
and
electricity
Electricity is the set of physical phenomena associated with the presence and motion of matter that has a property of electric charge. Electricity is related to magnetism, both being part of the phenomenon of electromagnetism, as describe ...
brittle
A material is brittle if, when subjected to stress, it fractures with little elastic deformation and without significant plastic deformation. Brittle materials absorb relatively little energy prior to fracture, even those of high strength. Br ...
or crumbly with low mechanical and structural strength, and poor to good conductors.
The internal structures and bonding arrangements of the nonmetals explain their differences in form. Those existing as discrete atoms (e.g. xenon) or molecules (e.g. oxygen, sulfur and bromine) have low melting and boiling points as they are held together by weak
London dispersion forces
London dispersion forces (LDF, also known as dispersion forces, London forces, instantaneous dipole–induced dipole forces, fluctuating induced dipole bonds or loosely as van der Waals forces) are a type of intermolecular force acting between a ...
acting between their atoms or molecules. Many are gases at room temperature. Nonmetals that form giant structures, such as chains of up to 1,000 atoms (e.g. selenium), sheets (e.g. carbon) or 3D lattices (e.g. silicon), have higher melting and boiling points, as it takes more energy to overcome their stronger
covalent bond
A covalent bond is a chemical bond that involves the sharing of electrons to form electron pairs between atoms. These electron pairs are known as shared pairs or bonding pairs. The stable balance of attractive and repulsive forces between ato ...
s, so they are all solids. Those closer to the left side of the periodic table, or further down a column, often have some weak metallic interactions between their molecules, chains, or layers, consistent with their proximity to the metals; this occurs in boron, carbon, phosphorus, arsenic, selenium, antimony, tellurium, and iodine.
Nonmetallic elements are either shiny, colored, or colorless. For boron, graphitic carbon, silicon, black phosphorus, germanium, arsenic, selenium, antimony, tellurium and iodine, their structures feature varying degrees of delocalised electrons that scatter incoming visible light, resulting in a shiny appearance. The colored nonmetals (sulfur, fluorine, chlorine, bromine) absorb some colours (wavelengths) and transmit the complementary colours. For chlorine, its "familiar yellow-green colour...is due to a broad region of absorption in the violet and blue regions of the spectrum". For the colorless nonmetals (hydrogen, nitrogen, oxygen, and the noble gases) their electrons are held sufficiently strongly such that no absorption occurs in the visible part of the spectrum, and all visible light is transmitted.
The electrical and thermal conductivities of nonmetals and the brittle nature of the solids are likewise related to their internal arrangements. Whereas good conductivity and plasticity (malleability, ductility) are ordinarily associated with the presence of free moving and uniformly distributed electrons in metals the electrons in nonmetals typically lack such mobility. Among the nonmetallic elements, good electrical and thermal conductivity occurs only in carbon, arsenic and antimony. Good thermal conductivity otherwise occurs only in boron, silicon, phosphorus, and germanium; such conductivity is transmitted though vibrations of the crystalline lattices of these elements. Moderate electrical conductivity occurs in boron, silicon, phosphorus, germanium, selenium, tellurium and iodine. Plasticity occurs in limited circumstances only in carbon, phosphorus, sulfur, and selenium.
The physical differences between metals and nonmetals arise from internal and external atomic forces. Internally, the
positive charge
Electric charge is the physical property of matter that causes charged matter to experience a force when placed in an electromagnetic field. Electric charge can be ''positive'' or ''negative'' (commonly carried by protons and electrons resp ...
arising 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 the protons in nearby atoms. When the external forces are greater than, or equal to, the internal force, outer electrons are expected to become free to move between atoms, and metallic properties are predicted. Otherwise nonmetallic properties are expected.
Chemical
Nonmetals have moderate to high values of electronegativity and tend to form acidic compounds. For example, the solid nonmetals (including metalloids) react with
nitric acid
Nitric acid is the inorganic compound with the formula . It is a highly corrosive mineral acid. The compound is colorless, but older samples tend to be yellow cast due to decomposition into oxides of nitrogen. Most commercially available ni ...
to form either an acid, or an oxide that has acidic properties predominating.
They tend to gain or share electrons when they react, unlike metals which tend to donate electrons. Given the stability of the
electron configuration
In atomic physics and quantum chemistry, the electron configuration is the distribution of electrons of an atom or molecule (or other physical structure) in atomic or molecular orbitals. For example, the electron configuration of the neon ato ...
s of the noble gases (which have full outer shells), nonmetals generally gain enough electrons to give them the electron configuration of the following noble gas, whereas metals tend to lose electrons sufficient to leave them with the electron configuration of the preceding noble gas. For nonmetallic elements this tendency is summarized in the
duet
A duet is a musical composition for two performers in which the performers have equal importance to the piece, often a composition involving two singers or two pianists. It differs from a harmony, as the performers take turns performing a sol ...
and
octet rule
The octet rule is a chemical rule of thumb that reflects the theory that main-group elements tend to bond in such a way that each atom has eight electrons in its valence shell, giving it the same electronic configuration as a noble gas. The rul ...
s of thumb (and for metals there is a less rigorously predictive 18-electron rule).
Nonmetals mostly have higher
ionization energies
Ionization, or Ionisation is the process by which an atom or a molecule acquires a negative or positive charge by gaining or losing electrons, often in conjunction with other chemical changes. The resulting electrically charged atom or molecul ...
electronegativity
Electronegativity, symbolized as , is the tendency for an atom of a given chemical element to attract shared electrons (or electron density) when forming a chemical bond. An atom's electronegativity is affected by both its atomic number and the ...
values, and
standard reduction potential
Redox potential (also known as oxidation / reduction potential, ''ORP'', ''pe'', ''E_'', or E_) is a measure of the tendency of a chemical species to acquire electrons from or lose electrons to an electrode and thereby be reduced or oxidised respe ...
s than metals. In general, the higher these values the more nonmetallic is the element.
The chemical differences between metals and nonmetals largely arise from the attractive force between the positive nuclear charge of an individual atom and its negatively charged outer electrons. From left to right across each period of the periodic table the nuclear charge increases as the number of
proton
A proton is a stable subatomic particle, symbol , H+, or 1H+ with a positive electric charge of +1 ''e'' elementary charge. Its mass is slightly less than that of a neutron and 1,836 times the mass of an electron (the proton–electron mass ...
s in the
atomic nucleus
The atomic nucleus is the small, dense region consisting of protons and neutrons at the center of an atom, discovered in 1911 by Ernest Rutherford based on the 1909 Geiger–Marsden gold foil experiment. After the discovery of the neutron ...
increases. There is an associated reduction in atomic radius as the increasing nuclear charge draws the outer electrons closer to the core. In metals, the effect of the nuclear charge is generally weaker than for nonmetallic elements. In bonding, metals therefore tend to lose electrons, and form positively charged or polarized atoms or ions whereas nonmetals tend to gain those same electrons due to their stronger nuclear charge, and form negatively charged ions or polarized atoms.
The number of compounds formed by nonmetals is vast. The first ten places in a "top 20" table of elements most frequently encountered in 895,501,834 compounds, as listed in the
Chemical Abstracts Service
CAS (formerly Chemical Abstracts Service) is a division of the American Chemical Society. It is a source of chemical information. CAS is located in Columbus, Ohio, United States.
Print periodicals
''Chemical Abstracts'' is a periodical index th ...
register for November 2, 2021, were occupied by nonmetals. Hydrogen, carbon, oxygen and nitrogen were collectively found in the majority (80%) of compounds. Silicon, a metalloid, was in 11th place. The highest rated metal, with an occurrence frequency of 0.14%, was iron, in 12th place. A few examples of nonmetal compounds are:
boric acid
Boric acid, more specifically orthoboric acid, is a compound of boron, oxygen, and hydrogen with formula . It may also be called hydrogen borate or boracic acid. It is usually encountered as colorless crystals or a white powder, that dissolve ...
(), used in
ceramic glazes
Ceramic glaze is an impervious layer or coating of a vitreous substance which has been fused to a pottery body through firing. Glaze can serve to color, decorate or waterproof an item. Glazing renders earthenware vessels suitable for holdin ...
;
selenocysteine
Selenocysteine (symbol Sec or U, in older publications also as Se-Cys) is the 21st proteinogenic amino acid. Selenoproteins contain selenocysteine residues. Selenocysteine is an analogue of the more common cysteine with selenium in place of the ...
(), the 21st
amino acid
Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although hundreds of amino acids exist in nature, by far the most important are the alpha-amino acids, which comprise proteins. Only 22 alpha ...
teflon
Polytetrafluoroethylene (PTFE) is a synthetic fluoropolymer of tetrafluoroethylene that has numerous applications. It is one of the best-known and widely applied PFAS. The commonly known brand name of PTFE-based composition is Teflon by Chemo ...
()''n''), as used in non-stick coatings for pans and other cookware.
Complications
Complicating the chemistry of the nonmetals are the anomalies seen in the first row of each
periodic table block
A block of the periodic table is a set of elements unified by the atomic orbitals their valence electrons or vacancies lie in. The term appears to have been first used by Charles Janet. Each block is named after its characteristic orbital: s-blo ...
. These anomalies are prominent in hydrogen, boron (whether as a nonmetal or metalloid), carbon, nitrogen, oxygen and fluorine. In later rows they manifest as secondary periodicity or non-uniform periodic trends going down most of the p-block groups, and unusual oxidation states in the heavier nonmetals.
First row anomaly
Starting with hydrogen, the first row anomaly largely arises from the electron configurations of the elements concerned. Hydrogen is noted for the different ways it forms bonds. It most commonly forms covalent bonds. It can lose its single electron in aqueous solution, leaving behind a bare proton with tremendous polarizing power. This consequently attaches itself to the lone electron pair of an oxygen atom in a water molecule, thereby forming the basis of acid-base chemistry. A hydrogen atom in a molecule can form a second, weaker, bond with an atom or group of atoms in another molecule. Such bonding, "helps give
snowflake
A snowflake is a single ice crystal that has achieved a sufficient size, and may have amalgamated with others, which falls through the Earth's atmosphere as snow.Knight, C.; Knight, N. (1973). Snow crystals. Scientific American, vol. 228, no. ...
double helix
A double is a look-alike or doppelgänger; one person or being that resembles another.
Double, The Double or Dubble may also refer to:
Film and television
* Double (filmmaking), someone who substitutes for the credited actor of a character
* ...
; shapes the three-dimensional forms of
protein
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, res ...
s; and even raises water's boiling point high enough to make a decent cup of tea."
Hydrogen and helium, and boron to neon have unusually small atomic radii. This occurs because the 1s and 2p subshells have no inner analogues (i.e., 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.Siekierski & Burgess 2002, pp. 24–25 Ionization energies and electronegativities among these elements are consequently higher than would otherwise be expected, having regard to
periodic trends
Periodic trends are specific patterns that are present in the periodic table that illustrate different aspects of a certain element. They were discovered by the Russian chemist Dmitri Mendeleev in the year 1863. Major periodic trends include atom ...
. The small atomic radii of carbon, nitrogen, and oxygen facilitate the formation of
double
A double is a look-alike or doppelgänger; one person or being that resembles another.
Double, The Double or Dubble may also refer to:
Film and television
* Double (filmmaking), someone who substitutes for the credited actor of a character
* ...
or
triple
Triple is used in several contexts to mean "threefold" or a " treble":
Sports
* Triple (baseball), a three-base hit
* A basketball three-point field goal
* A figure skating jump with three rotations
* In bowling terms, three strikes in a row
* ...
bonds.
While it would normally be expected that hydrogen and helium, on electron configuration consistency grounds, would be located atop the s-block elements, the first row anomaly in these two elements is strong enough to warrant alternative placements. Hydrogen is occasionally positioned over fluorine, in group 17 rather than over lithium in group 1. Helium is regularly positioned over neon, in group 18, rather than over beryllium, in group 2.
Secondary periodicity
Immediately after the first row of
d-block
A block of the periodic table is a set of elements unified by the atomic orbitals their valence electrons or vacancies lie in. The term appears to have been first used by Charles Janet. Each block is named after its characteristic orbital: s-blo ...
metals, scandium to zinc, the 3d electrons in the
p-block
A block of the periodic table is a set of elements unified by the atomic orbitals their valence electrons or vacancies lie in. The term appears to have been first used by Charles Janet. Each block is named after its characteristic orbital: s-blo ...
elements i.e., gallium (a metal), germanium, arsenic, selenium, and bromine, are not as effective at shielding the increased positive nuclear charge. A similar effect accompanies the appearance of fourteen f-block metals between
barium
Barium is a chemical element with the symbol Ba and atomic number 56. It is the fifth element in group 2 and is a soft, silvery alkaline earth metal. Because of its high chemical reactivity, barium is never found in nature as a free element.
Th ...
and
lutetium
Lutetium is a chemical element with the symbol Lu and atomic number 71. It is a silvery white metal, which resists corrosion in dry air, but not in moist air. Lutetium is the last element in the lanthanide series, and it is traditionally counted am ...
hafnium
Hafnium is a chemical element with the symbol Hf and atomic number 72. A lustrous, silvery gray, tetravalent transition metal, hafnium chemically resembles zirconium and is found in many zirconium minerals. Its existence was predicted by Dmitri M ...
(Hf) onwards. The net result, especially for the group 13–15 elements, is that there is an alternation in some periodic trends going down groups 13 to 17.
Unusual oxidation states
The larger atomic radii of the heavier group 15–18 nonmetals enable higher
bulk coordination number
In chemistry, crystallography, and materials science, the coordination number, also called ligancy, of a central atom in a molecule or crystal is the number of atoms, molecules or ions bonded to it. The ion/molecule/atom surrounding the central io ...
s, and result in lower electronegativity values that better tolerate higher positive charges. The elements involved are thereby able to exhibit
oxidation state
In chemistry, the oxidation state, or oxidation number, is the hypothetical charge of an atom if all of its bonds to different atoms were fully ionic. It describes the degree of oxidation (loss of electrons) of an atom in a chemical compound. C ...
s other than the lowest for their group (that is, 3, 2, 1, or 0) for example in
phosphorus pentachloride
Phosphorus pentachloride is the chemical compound with the formula PCl5. It is one of the most important phosphorus chlorides, others being PCl3 and POCl3. PCl5 finds use as a chlorinating reagent. It is a colourless, water-sensitive and mois ...
(PCl5),
sulfur hexafluoride
Sulfur hexafluoride or sulphur hexafluoride (British spelling) is an inorganic compound with the formula SF6. It is a colorless, odorless, non- flammable, and non-toxic gas. has an octahedral geometry, consisting of six fluorine atoms attach ...
(SF6),
iodine heptafluoride
Iodine heptafluoride, also known as iodine(VII) fluoride or iodine fluoride, is an interhalogen compound with the chemical formula I F7. It has an unusual pentagonal bipyramidal structure, as predicted by VSEPR theory. The molecule can undergo ...
(IF7), and
xenon difluoride
Xenon difluoride is a powerful fluorinating agent with the chemical formula , and one of the most stable xenon compounds. Like most covalent inorganic fluorides it is moisture-sensitive. It decomposes on contact with water vapor, but is otherwis ...
Encyclopædia Britannica
The (Latin for "British Encyclopædia") is a general knowledge English-language encyclopaedia. It is published by Encyclopædia Britannica, Inc.; the company has existed since the 18th century, although it has changed ownership various t ...
periodic table recognizes noble gases, halogens, and other nonmetals, and splits the elements commonly recognized as metalloids between "other metals" and "other nonmetals". The
Royal Society of Chemistry
The Royal Society of Chemistry (RSC) is a learned society (professional association) in the United Kingdom with the goal of "advancing the chemical sciences". It was formed in 1980 from the amalgamation of the Chemical Society, the Royal Inst ...
periodic table instead uses a different color for each of its eight main groups, and nonmetals can be found in seven of these.
From right to left in periodic table terms, three or four kinds of nonmetals are more or less commonly discerned.
These are:
*the relatively inert noble gases;
*a set of chemically strong halogen elements—fluorine, chlorine, bromine and iodine—sometimes referred to as nonmetal halogens (the term used here) or stable halogens;
*a set of unclassified nonmetals, including elements such as hydrogen, carbon, nitrogen, and oxygen, with no widely recognized collective name; and
*the chemically weak nonmetallic metalloidsBailar et al. 1989, p. 742 sometimes considered to be nonmetals and sometimes not.
Since the metalloids occupy "frontier territory", where metals meet nonmetals, their treatment varies from author to author. Some consider them separate from both metals and nonmetals; some regard them as nonmetals or as a sub-class of nonmetals. Other authors count some of them as metals, for example arsenic and antimony, due to their similarities to
heavy metals
upright=1.2, Crystals of osmium, a heavy metal nearly twice as dense as lead">lead.html" ;"title="osmium, a heavy metal nearly twice as dense as lead">osmium, a heavy metal nearly twice as dense as lead
Heavy metals are generally defined as ...
.
Metalloids are here treated as nonmetals in light of their chemical behavior, and for comparative purposes.
Aside from the metalloids, some boundary fuzziness and overlapping (as occurs with classification schemes generally) can be discerned among the other nonmetal subclasses. Carbon, phosphorus, selenium, iodine border the metalloids and show some metallic character, as does hydrogen. Among the noble gases, radon is the most metallic and begins to show some
cation
An ion () is an atom or molecule with a net electrical charge.
The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by conven ...
ic behavior, which is unusual for a nonmetal.
Noble gases
Six nonmetals are classified as noble gases:
helium
Helium (from el, ἥλιος, helios, lit=sun) is a chemical element with the symbol He and atomic number 2. It is a colorless, odorless, tasteless, non-toxic, inert, monatomic gas and the first in the noble gas group in the periodic ta ...
, neon, argon, krypton,
xenon
Xenon is a chemical element with the symbol Xe and atomic number 54. It is a dense, colorless, odorless noble gas found in Earth's atmosphere in trace amounts. Although generally unreactive, it can undergo a few chemical reactions such as the ...
, and the radioactive radon. In conventional periodic tables they occupy the rightmost column. They are called ''noble gases'' in light of their characteristically very low
chemical reactivity
In chemistry, reactivity is the impulse for which a chemical substance undergoes a chemical reaction, either by itself or with other materials, with an overall release of energy.
''Reactivity'' refers to:
* the chemical reactions of a single su ...
.
They have very similar properties, with all of them being colorless, odorless, and nonflammable. With their closed outer electron shells the noble gases have feeble interatomic forces of attraction resulting in very low melting and boiling points. That is why they are all gases under
standard conditions
Standard temperature and pressure (STP) are standard sets of conditions for experimental measurements to be established to allow comparisons to be made between different sets of data. The most used standards are those of the International Union ...
, even those with
atomic mass
The atomic mass (''m''a or ''m'') is the mass of an atom. Although the SI unit of mass is the kilogram (symbol: kg), atomic mass is often expressed in the non-SI unit dalton (symbol: Da) – equivalently, unified atomic mass unit (u). 1&n ...
es larger than many normally solid elements.
Chemically, the noble gases have relatively high ionization energies, nil or negative electron affinities, and relatively high electronegativities. Compounds of the noble gases number in the hundreds although the list continues to grow, with most of these involving oxygen or fluorine combining with either krypton, xenon or radon.
In periodic table terms, an analogy can be drawn between the
noble gas
The noble gases (historically also the inert gases; sometimes referred to as aerogens) make up a class of chemical elements with similar properties; under standard conditions, they are all odorless, colorless, monatomic gases with very low ch ...
es and
noble metal
A noble metal is ordinarily regarded as a metallic chemical element that is generally resistant to corrosion and is usually found in nature in its raw form. Gold, platinum, and the other platinum group metals ( ruthenium, rhodium, palladium, o ...
s such as platinum and gold, with the latter being similarly reluctant to enter into chemical combination. As a further example, xenon, in the +8 oxidation state, forms a pale yellow explosive oxide, XeO4, while
osmium
Osmium (from Greek grc, ὀσμή, osme, smell, label=none) is a chemical element with the symbol Os and atomic number 76. It is a hard, brittle, bluish-white transition metal in the platinum group that is found as a trace element in alloys, ...
, another noble metal, forms a yellow strongly oxidizing oxide, OsO4. There are parallels too in the formulas of the oxyfluorides: XeO2F4 and OsO2F4, and XeO3F2 and OsO3F2.
About 1015 tonnes of noble gases are present in the Earth's atmosphere. Helium is additionally found in
natural gas
Natural gas (also called fossil gas or simply gas) is a naturally occurring mixture of gaseous hydrocarbons consisting primarily of methane in addition to various smaller amounts of other higher alkanes. Low levels of trace gases like carbon d ...
to the extent of as much as 7%. Radon diffuses out of rocks, where it is formed during the natural decay sequence of
uranium
Uranium is a chemical element with the symbol U and atomic number 92. It is a silvery-grey metal in the actinide series of the periodic table. A uranium atom has 92 protons and 92 electrons, of which 6 are valence electrons. Uranium is weak ...
and
thorium
Thorium is a weakly radioactive metallic chemical element with the symbol Th and atomic number 90. Thorium is silvery and tarnishes black when it is exposed to air, forming thorium dioxide; it is moderately soft and malleable and has a high ...
. In 2014 it was reported that the Earth's core may contain about 1013 tons of xenon, in the form of stable XeFe3 and XeNi3intermetallic compounds. This may explain why "studies of the Earth's atmosphere have shown that more than 90% of the expected amount of Xe is depleted."
Nonmetal halogens
While the nonmetal halogens are markedly reactive and corrosive elements, they can be found in such mundane compounds as
toothpaste
Toothpaste is a paste or gel dentifrice used with a toothbrush to clean and maintain the aesthetics and health of teeth. Toothpaste is used to promote oral hygiene: it is an abrasive that aids in removing dental plaque and food from the teeth, ...
table salt
Salt is a mineral composed primarily of sodium chloride (NaCl), a chemical compound belonging to the larger class of salts; salt in the form of a natural crystalline mineral is known as rock salt or halite. Salt is present in vast quantitie ...
(NaCl); swimming pool disinfectant ( NaBr); or food supplements ( KI). The word "halogen" means "
salt
Salt is a mineral composed primarily of sodium chloride (NaCl), a chemical compound belonging to the larger class of salts; salt in the form of a natural crystalline mineral is known as rock salt or halite. Salt is present in vast quant ...
former".
Physically, fluorine and chlorine are pale yellow and yellowish green gases; bromine is a reddish-brown liquid (usually topped by a layer of its fumes); and iodine, under white light, is a metallic-looking solid. Electrically, the first three are insulators while iodine is a
semiconductor
A semiconductor is a material which has an electrical conductivity value falling between that of a conductor, such as copper, and an insulator, such as glass. Its resistivity falls as its temperature rises; metals behave in the opposite way ...
(along its planes).Greenwood & Earnshaw 2002, p. 804
Chemically, they have high ionization energies, electron affinities, and electronegativity values, and are mostly relatively strong
oxidizing agent
An oxidizing agent (also known as an oxidant, oxidizer, electron recipient, or electron acceptor) is a substance in a redox chemical reaction that gains or " accepts"/"receives" an electron from a (called the , , or ). In other words, an oxi ...
s. Manifestations of this status include their corrosive nature.Daniel & Rapp 1976, p. 55 All four exhibit a tendency to form predominately
ionic compound
In chemistry, an ionic compound is a chemical compound composed of ions held together by electrostatic forces termed ionic bonding. The compound is neutral overall, but consists of positively charged ions called cations and negatively charged ...
s with metalsCotton et al. 1999, p. 554 whereas the remaining nonmetals, bar oxygen, tend to form predominately
covalent compound
A covalent bond is a chemical bond that involves the sharing of electrons to form electron pairs between atoms. These electron pairs are known as shared pairs or bonding pairs. The stable balance of attractive and repulsive forces between atoms ...
s with metals. The reactive and strongly electronegative nature of the nonmetal halogens represents the epitome of nonmetallic character.Lanford 1959, p. 176
In periodic table terms, the counterparts of the highly nonmetallic halogens in group 17 are the highly reactive alkali metals, such as sodium and potassium, in group 1. Most of the alkali metals, as if in imitation of the nonmetal halogens, are known to form –1 anions (something that rarely occurs among metals).
The nonmetal halogens are found in salt-related minerals. Fluorine occurs in
fluorite
Fluorite (also called fluorspar) is the mineral form of calcium fluoride, CaF2. It belongs to the halide minerals. It crystallizes in isometric cubic habit, although octahedral and more complex isometric forms are not uncommon.
The Mohs sca ...
(CaF2), a widespread mineral. Chlorine, bromine and iodine are found in brines. Exceptionally, a 2012 study reported the presence of 0.04% native fluorine () by weight in
antozonite
Antozonite (historically known as Stinkspat, Stinkfluss, Stinkstein, Stinkspar and fetid fluorite) is a radioactive fluorite variety first found in Wölsendorf, Bavaria, in 1841, and named in 1862.
It is characterized by the presence of multip ...
, attributing these inclusions as a result of radiation from the presence of tiny amounts of
uranium
Uranium is a chemical element with the symbol U and atomic number 92. It is a silvery-grey metal in the actinide series of the periodic table. A uranium atom has 92 protons and 92 electrons, of which 6 are valence electrons. Uranium is weak ...
.
Unclassified nonmetals
After the nonmetallic elements are classified as either noble gases, halogens or metalloids (following), the remaining seven nonmetals are hydrogen, carbon, nitrogen, oxygen, phosphorus, sulfur and selenium. In their most stable forms, three are colorless gases (H, N, O); three have a metal-like appearance (C, P, Se); and one is yellow (S). Electrically, graphitic carbon is a
semimetal
A semimetal is a material with a very small overlap between the bottom of the conduction band and the top of the valence band.
According to electronic band theory, solids can be classified as insulators, semiconductors, semimetals, or metals ...
along its planes and a
semiconductor
A semiconductor is a material which has an electrical conductivity value falling between that of a conductor, such as copper, and an insulator, such as glass. Its resistivity falls as its temperature rises; metals behave in the opposite way ...
in a direction perpendicular to its planes; phosphorus and selenium are semiconductors; and hydrogen, nitrogen, oxygen, and sulfur are insulators.
They are generally regarded as being too diverse to merit a collective examination,Cao et al. 2021, pp. 20–21 and have been referred to as ''other nonmetals'', or more plainly as ''nonmetals'', located between the ''metalloids'' and the ''halogens.'' Consequently, their chemistry tends to be taught disparately, according to their four respective periodic table groups, for example: hydrogen in group 1; the group 14 nonmetals (carbon, and possibly silicon and germanium); the group 15 nonmetals (nitrogen, phosphorus, and possibly arsenic and antimony); and the group 16 nonmetals (oxygen, sulfur, selenium, and possibly tellurium). Other subdivisions are possible according to the individual preferences of authors.
Hydrogen, in particular, behaves in some respects like a metal and in others like a nonmetal. Like a metal it can (first) lose its single electron; it can stand in for alkali metals in typical alkali metal structures; and is capable of forming alloy-like
hydride
In chemistry, a hydride is formally the anion of hydrogen( H−). The term is applied loosely. At one extreme, all compounds containing covalently bound H atoms are called hydrides: water (H2O) is a hydride of oxygen, ammonia is a hydride ...
s, featuring metallic bonding, with some
transition metal
In chemistry, a transition metal (or transition element) is a chemical element in the d-block of the periodic table (groups 3 to 12), though the elements of group 12 (and less often group 3) are sometimes excluded. They are the elements that can ...
s.Wiberg 2001, pp. 255–257 On the other hand, it is an insulating diatomic gas, like a typical nonmetal, and in chemical reactions has a tendency to eventually attain the electron configuration of helium. It does this by way of forming a covalent or ionic bond or, if it has lost its electron, attaching itself to a lone pair of electrons.
Some or all of these nonmetals nevertheless have several shared properties. Most of them, being less reactive than the halogens, can occur naturally in the environment. They have prominent
biological
Biology is the scientific study of life. It is a natural science with a broad scope but has several unifying themes that tie it together as a single, coherent field. For instance, all organisms are made up of cells that process hereditary in ...
and
geochemical
Geochemistry is the science that uses the tools and principles of chemistry to explain the mechanisms behind major geological systems such as the Earth's crust and its oceans. The realm of geochemistry extends beyond the Earth, encompassing the e ...
roles. While their physical and chemical character is "moderately non-metallic", on a net basis, all of them have corrosive aspects. Hydrogen can corrode metals. Carbon corrosion can occur in
fuel cell
A fuel cell is an electrochemical cell that converts the chemical energy of a fuel (often hydrogen fuel, hydrogen) and an oxidizing agent (often oxygen) into electricity through a pair of redox reactions. Fuel cells are different from most bat ...
s.
Acid rain
Acid rain is rain or any other form of precipitation that is unusually acidic, meaning that it has elevated levels of hydrogen ions (low pH). Most water, including drinking water, has a neutral pH that exists between 6.5 and 8.5, but ac ...
is caused by dissolved nitrogen or sulfur. Oxygen corrodes iron via
rust
Rust is an iron oxide, a usually reddish-brown oxide formed by the reaction of iron and oxygen in the catalytic presence of water or air moisture. Rust consists of hydrous iron(III) oxides (Fe2O3·nH2O) and iron(III) oxide-hydroxide (FeO( ...
. White phosphorus, the most unstable form, ignites in air and produces
phosphoric acid
Phosphoric acid (orthophosphoric acid, monophosphoric acid or phosphoric(V) acid) is a colorless, odorless phosphorus-containing solid, and inorganic compound with the chemical formula . It is commonly encountered as an 85% aqueous solution, w ...
residue. Untreated selenium in soils can give rise to corrosive
hydrogen selenide
Hydrogen selenide is an inorganic compound with the formula H2Se. This hydrogen chalcogenide is the simplest and most commonly encountered hydride of selenium. H2Se is a colorless, flammable gas under standard conditions. It is the most toxic sel ...
gas. When combined with metals, the unclassified nonmetals can form high
hardness
In materials science, hardness (antonym: softness) is a measure of the resistance to localized plastic deformation induced by either mechanical indentation or abrasion. In general, different materials differ in their hardness; for example hard ...
(
interstitial
An interstitial space or interstice is a space between structures or objects.
In particular, interstitial may refer to:
Biology
* Interstitial cell tumor
* Interstitial cell, any cell that lies between other cells
* Interstitial collagenase ...
or
refractory
In materials science, a refractory material or refractory is a material that is resistant to decomposition by heat, pressure, or chemical attack, and retains strength and form at high temperatures. Refractories are polycrystalline, polyphase, ...
) compounds, on account of their relatively small atomic radii and sufficiently low ionization energy values. They show a tendency to bond to themselves, especially in solid compounds.Diagonal periodic table relationships among these nonmetals echo similar relationships among the metalloids.
In periodic table terms, a geographic analogy is seen between the unclassified nonmetals and transition metals. The unclassified nonmetals occupy territory between the strongly nonmetallic halogens on the right and the weakly nonmetallic metalloids on the left. The transition metals occupy territory, "between the virulent and violent metals on the left of the periodic table, and the calm and contented metals to the right... nd.. form a transitional bridge between the two".
Unclassified nonmetals typically occur in elemental forms (oxygen, sulfur) or are found in association with either of these two elements:Cox 1997, pp. 130–132; Emsley 2011, passim
* Hydrogen occurs in the world's oceans as a component of water, and in
natural gas
Natural gas (also called fossil gas or simply gas) is a naturally occurring mixture of gaseous hydrocarbons consisting primarily of methane in addition to various smaller amounts of other higher alkanes. Low levels of trace gases like carbon d ...
as a component of
methane
Methane ( , ) is a chemical compound with the chemical formula (one carbon atom bonded to four hydrogen atoms). It is a group-14 hydride, the simplest alkane, and the main constituent of natural gas. The relative abundance of methane ...
and
hydrogen sulfide
Hydrogen sulfide is a chemical compound with the formula . It is a colorless chalcogen-hydride gas, and is poisonous, corrosive, and flammable, with trace amounts in ambient atmosphere having a characteristic foul odor of rotten eggs. The under ...
.
* Carbon occurs in limestone, dolomite, and marble, as carbonates. Less well known is carbon as graphite, which mainly occurs in
metamorphic
Metamorphic rocks arise from the transformation of existing rock to new types of rock in a process called metamorphism. The original rock (protolith) is subjected to temperatures greater than and, often, elevated pressure of or more, causi ...
silicate rocks as a result of the compression and heating of sedimentary carbon compounds.
* Oxygen is found in the atmosphere; in the oceans as a component of water; and in the crust as
oxide mineral
The oxide mineral class includes those minerals in which the oxide anion (O2−) is bonded to one or more metal alloys. The hydroxide-bearing minerals are typically included in the oxide class. The minerals with complex anion groups such as the ...
s.
* Phosphorus minerals are widespread, usually as phosphorus-oxygen
phosphates
In chemistry, a phosphate is an anion, salt, functional group or ester derived from a phosphoric acid. It most commonly means orthophosphate, a derivative of orthophosphoric acid .
The phosphate or orthophosphate ion is derived from phosph ...
.
* Elemental sulfur can be found in or near hot springs and volcanic regions in many parts of the world; sulfur minerals are widespread, usually as
sulfides
Sulfide (British English also sulphide) is an inorganic anion of sulfur with the chemical formula S2− or a compound containing one or more S2− ions. Solutions of sulfide salts are corrosive. ''Sulfide'' also refers to chemical compounds la ...
or oxygen-sulfur
sulfates
The sulfate or sulphate ion is a polyatomic anion with the empirical formula . Salts, acid derivatives, and peroxides of sulfate are widely used in industry. Sulfates occur widely in everyday life. Sulfates are salts of sulfuric acid and many a ...
.
* Selenium occurs in metal sulfide ores, where it partially replaces the sulfur; elemental selenium is occasionally found.
Metalloids
The six elements more commonly recognized as metalloids are boron, silicon, germanium, arsenic, antimony, and tellurium, each having a metallic appearance. On a standard periodic table, they occupy a diagonal area in the p-block extending from boron at the upper left to tellurium at lower right, along the dividing line between metals and nonmetals shown on some tables.Vernon 2013
They are brittle and poor to good conductors of heat and electricity. Boron, silicon, germanium and tellurium are semiconductors. Arsenic and antimony have the
electronic structure
In quantum chemistry, electronic structure is the state of motion of electrons in an electrostatic field created by stationary nuclei. The term encompasses both the wave functions of the electrons and the energies associated with them. Electr ...
s of
semimetal
A semimetal is a material with a very small overlap between the bottom of the conduction band and the top of the valence band.
According to electronic band theory, solids can be classified as insulators, semiconductors, semimetals, or metals ...
s although both have less stable semiconducting
forms
Form is the shape, visual appearance, or configuration of an object. In a wider sense, the form is the way something happens.
Form also refers to:
*Form (document), a document (printed or electronic) with spaces in which to write or enter data
* ...
.
Chemically the metalloids generally behave like (weak) nonmetals. Among the nonmetallic elements they tend to have the lowest ionization energies, electron affinities, and electronegativity values, and are relatively weak oxidizing agents. They further demonstrate a tendency to form alloys with metals.
In periodic table terms, to the left of the weakly nonmetallic metalloids are an indeterminate set of weakly metallic metals (such as tin,
lead
Lead is a chemical element with the symbol Pb (from the Latin ) and atomic number 82. It is a heavy metal that is denser than most common materials. Lead is soft and malleable, and also has a relatively low melting point. When freshly cut, ...
and
bismuth
Bismuth is a chemical element with the symbol Bi and atomic number 83. It is a post-transition metal and one of the pnictogens, with chemical properties resembling its lighter group 15 siblings arsenic and antimony. Elemental bismuth occurs ...
) sometimes referred to as
post-transition metals
The metallic elements in the periodic table located between the transition metals and the chemically weak nonmetallic metalloids have received many names in the literature, such as ''post-transition metals'', ''poor metals'', ''other metals'', ...
. Dingle explains the situation this way:
:... with 'no-doubt' metals on the far left of the table, and no-doubt non-metals on the far right... the gap between the two extremes is bridged first by the poor ( post-transition) metals, and then by the metalloids—which, perhaps by the same token, might collectively be renamed the 'poor non-metals'.
The metalloids tend to be found in forms combined with oxygen or sulfur or (in the case of tellurium) gold or silver. Boron is found in boron-oxygen
borate
A borate is any of several boron oxyanions, negative ions consisting of boron and oxygen, such as orthoborate , metaborate , or tetraborate ; or any salt with such anions, such as sodium metaborate, and disodium tetraborate . The name also re ...
minerals including in volcanic spring waters. Silicon occurs in the silicon-oxygen mineral
silica
Silicon dioxide, also known as silica, is an oxide of silicon with the chemical formula , most commonly found in nature as quartz and in various living organisms. In many parts of the world, silica is the major constituent of sand. Silica is ...
(sand). Germanium, arsenic and antimony are mainly found as components of
sulfide
Sulfide (British English also sulphide) is an inorganic anion of sulfur with the chemical formula S2− or a compound containing one or more S2− ions. Solutions of sulfide salts are corrosive. ''Sulfide'' also refers to chemical compounds la ...
ores. Tellurium occurs in
telluride mineral
A telluride mineral is a mineral that has the telluride anion as a main component.
Tellurides are similar to sulfides and are grouped with them in both the Dana and Strunz mineral classification systems.http://webmineral.com/strunz/II.shtml Webm ...
s of gold or silver. Native forms of arsenic, antimony and tellurium have been reported.
Allotropes
Most nonmetallic elements exist in allotropic forms. Carbon, for example, occurs as graphite, diamond and other forms. Such allotropes may exhibit physical properties that are more metallic or less nonmetallic.
Among the nonmetal halogens, and unclassified nonmetals:
* Iodine is known in a semiconducting
amorphous
In condensed matter physics and materials science, an amorphous solid (or non-crystalline solid, glassy solid) is a solid that lacks the long-range order that is characteristic of a crystal.
Etymology
The term comes from the Greek language, Gr ...
form.
* Graphite, the standard state of carbon, is a fairly good electrical conductor. The
diamond
Diamond is a solid form of the element carbon with its atoms arranged in a crystal structure called diamond cubic. Another solid form of carbon known as graphite is the chemically stable form of carbon at room temperature and pressure, b ...
allotrope of carbon is clearly nonmetallic, being translucent and an extremely poor electrical conductor. Carbon is known in several other allotropic forms, including semiconducting
buckminsterfullerene
Buckminsterfullerene is a type of fullerene with the formula C60. It has a cage-like fused-ring structure (truncated icosahedron) made of twenty hexagons and twelve pentagons, and resembles a soccer ball. Each of its 60 carbon atoms is bonded ...
, and
amorphous
In condensed matter physics and materials science, an amorphous solid (or non-crystalline solid, glassy solid) is a solid that lacks the long-range order that is characteristic of a crystal.
Etymology
The term comes from the Greek language, Gr ...
and
paracrystalline
In materials science, paracrystalline materials are defined as having short- and medium-range ordering in their lattice (similar to the liquid crystal phases) but lacking crystal-like long-range ordering at least in one direction.
Origin and ...
(mixed amorphous and crystalline) varieties.
* Nitrogen can form gaseous tetranitrogen (N4), an unstable polyatomic molecule with a lifetime of about one microsecond.
* Oxygen is a diatomic molecule in its standard state; it also exists as
ozone
Ozone (), or trioxygen, is an inorganic molecule with the chemical formula . It is a pale blue gas with a distinctively pungent smell. It is an allotrope of oxygen that is much less stable than the diatomic allotrope , breaking down in the l ...
(O3), an unstable nonmetallic allotrope with an "indoors"
half-life
Half-life (symbol ) is the time required for a quantity (of substance) to reduce to half of its initial value. The term is commonly used in nuclear physics to describe how quickly unstable atoms undergo radioactive decay or how long stable ...
of around half an hour, compared to about three days in ambient air at 20 °C.
* Phosphorus, uniquely, exists in several allotropic forms that are more stable than its standard state as white phosphorus (P4). The
white
White is the lightest color and is achromatic (having no hue). It is the color of objects such as snow, chalk, and milk, and is the opposite of black. White objects fully reflect and scatter all the visible wavelengths of light. White ...
black
Black is a color which results from the absence or complete absorption of visible light. It is an achromatic color, without hue, like white and grey. It is often used symbolically or figuratively to represent darkness. Black and white ha ...
allotropes are probably the best known; the first is an insulator; the latter two are semiconductors. Phosphorus also exists as
diphosphorus
Diphosphorus is an inorganic chemical with the chemical formula . Unlike nitrogen, its lighter pnictogen neighbor which forms a stable N2 molecule with a nitrogen to nitrogen triple bond, phosphorus prefers a tetrahedral form P4 because P-P pi ...
(P2), an unstable diatomic allotrope.
* Sulfur has more allotropes than any other element. Amorphous sulfur, a metastable mixture of such allotropes, is noted for its elasticity.
* Selenium has several nonmetallic allotropes, all of which are much less electrically conducting than its standard state of gray "metallic" selenium.
All the elements most commonly recognized as metalloids form allotropes:
* Boron is known in several crystalline and amorphous forms.
* Silicon can form crystalline (diamond-like); amorphous; and
orthorhombic
In crystallography, the orthorhombic crystal system is one of the 7 crystal systems. Orthorhombic lattices result from stretching a cubic lattice along two of its orthogonal pairs by two different factors, resulting in a rectangular prism with ...
Si24 allotropes.
* At a pressure of about 10–11 GPa, germanium transforms to a metallic phase with the same tetragonal structure as tin. When decompressed—and depending on the speed of pressure release—metallic germanium forms a series of allotropes that are
metastable
In chemistry and physics, metastability denotes an intermediate energetic state within a dynamical system other than the system's state of least energy.
A ball resting in a hollow on a slope is a simple example of metastability. If the ball i ...
in ambient conditions.
* Arsenic and antimony form several well-known allotropes (yellow, grey, and black).
* Tellurium is known in crystalline and amorphous forms.
Other allotropic forms of nonmetallic elements are known, either under pressure or in
monolayer A monolayer is a single, closely packed layer of atoms, molecules, or cells. In some cases it is referred to as a self-assembled monolayer. Monolayers of layered crystals like graphene and molybdenum disulfide are generally called 2D materials.
C ...
s. Under sufficiently high pressures, at least half of the nonmetallic elements that are semiconductors or insulators, starting with phosphorus at 1.7 GPa, have been observed to form metallic allotropes. Single layer two-dimensional forms of nonmetals include
borophene
Borophene is a crystalline atomic monolayer of boron, i.e., it is a two-dimensional allotrope of boron and also known as ''boron sheet''.
First predicted by theory in the mid-1990s,
different borophene structures were experimentally confirmed i ...
(boron),
graphene
Graphene () is an allotrope of carbon consisting of a Single-layer materials, single layer of atoms arranged in a hexagonal lattice nanostructure.
phosphorene
Phosphorene is a two-dimensional material consisting of phosphorus. It consists of a single layer of the artificially made layered black phosphorus, the most stable allotrope of phosphorus. The designation phosphorene has been introduced in an ...
(phosphorus),
germanene
Germanene is a material made up of a single layer of germanium atoms. The material is created in a process similar to that of silicene and graphene, in which high vacuum and high temperature are used to deposit a layer of germanium atoms on a subs ...
Hydrogen and helium are estimated to make up approximately 99% of all ordinary matter in the universe and over 99.9% of its atoms. Oxygen is thought to be the next most abundant element, at about 0.1%. Less than five per cent of the universe is believed to be made of ordinary matter, represented by stars, planets and living beings. The balance is made of
dark energy
In physical cosmology and astronomy, dark energy is an unknown form of energy that affects the universe on the largest scales. The first observational evidence for its existence came from measurements of supernovas, which showed that the univ ...
and
dark matter
Dark matter is a hypothetical form of matter thought to account for approximately 85% of the matter in the universe. Dark matter is called "dark" because it does not appear to interact with the electromagnetic field, which means it does not ...
, both of which are currently poorly understood.
Five nonmetals namely hydrogen, carbon, nitrogen, oxygen and silicon constitute the bulk of the
Earth's crust
Earth's crust is Earth's thin outer shell of rock, referring to less than 1% of Earth's radius and volume. It is the top component of the lithosphere, a division of Earth's layers that includes the crust and the upper part of the mantle. The ...
,
atmosphere
An atmosphere () is a layer of gas or layers of gases that envelop a planet, and is held in place by the gravity of the planetary body. A planet retains an atmosphere when the gravity is great and the temperature of the atmosphere is low. A ...
,
hydrosphere
The hydrosphere () is the combined mass of water found on, under, and above the surface of a planet, minor planet, or natural satellite. Although Earth's hydrosphere has been around for about 4 billion years, it continues to change in shape. This ...
and
biomass
Biomass is plant-based material used as a fuel for heat or electricity production. It can be in the form of wood, wood residues, energy crops, agricultural residues, and waste from industry, farms, and households. Some people use the terms bio ...
, in the quantities shown in the table.
Extraction
Nonmetals, and metalloids, are extracted in their raw forms from:Emsley 2011, passim
* ''
brine
Brine is a high-concentration solution of salt (NaCl) in water (H2O). In diverse contexts, ''brine'' may refer to the salt solutions ranging from about 3.5% (a typical concentration of seawater, on the lower end of that of solutions used for ...
borate mineral
The borate minerals are minerals which contain a borate anion group. The borate (BO3) units may be polymerised similar to the SiO4 unit of the silicate mineral class. This results in B2O5, B3O6, B2O4 anions as well as more complex structures wh ...
s); carbon (coal; diamond; graphite); fluorine (
fluorite
Fluorite (also called fluorspar) is the mineral form of calcium fluoride, CaF2. It belongs to the halide minerals. It crystallizes in isometric cubic habit, although octahedral and more complex isometric forms are not uncommon.
The Mohs sca ...
); silicon (
silica
Silicon dioxide, also known as silica, is an oxide of silicon with the chemical formula , most commonly found in nature as quartz and in various living organisms. In many parts of the world, silica is the major constituent of sand. Silica is ...
); phosphorus (phosphates); antimony (
stibnite
Stibnite, sometimes called antimonite, is a sulfide mineral with the formula Sb2 S3. This soft grey material crystallizes in an orthorhombic space group. It is the most important source for the metalloid antimony. The name is derived from the ...
,
tetrahedrite
Tetrahedrite is a copper antimony sulfosalt mineral with formula: . It is the antimony endmember of the continuous solid solution series with arsenic-bearing tennantite. Pure endmembers of the series are seldom if ever seen in nature. Of the t ...
sodium iodide
Sodium iodide (chemical formula NaI) is an ionic compound formed from the chemical reaction of sodium metal and iodine. Under standard conditions, it is a white, water-soluble solid comprising a 1:1 mix of sodium cations (Na+) and iodide anions (I ...
);
* ''natural gas''—hydrogen, helium, sulfur; and
* ''ores'', as processing byproducts—germanium (
zinc
Zinc is a chemical element with the symbol Zn and atomic number 30. Zinc is a slightly brittle metal at room temperature and has a shiny-greyish appearance when oxidation is removed. It is the first element in group 12 (IIB) of the periodi ...
ores); arsenic (
copper
Copper is a chemical element with the symbol Cu (from la, cuprum) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pink ...
and
lead
Lead is a chemical element with the symbol Pb (from the Latin ) and atomic number 82. It is a heavy metal that is denser than most common materials. Lead is soft and malleable, and also has a relatively low melting point. When freshly cut, ...
ores); selenium, tellurium (copper ores); and radon (
uranium
Uranium is a chemical element with the symbol U and atomic number 92. It is a silvery-grey metal in the actinide series of the periodic table. A uranium atom has 92 protons and 92 electrons, of which 6 are valence electrons. Uranium is weak ...
-bearing ores).
Cost
Day to day costs will vary depending on purity, quantity, market conditions, and supplier surcharges.
Based on the available literature as at August 2022, while the cited costs of most nonmetals are less than the $US0.80 per gram cost of silver,
boron, phosphorus, germanium, xenon, and radon (notionally) are exceptions:
*Boron costs around $25 per gram for 99.7% pure polycrystalline chunks with a particle size of about 1 cm. Earlier, in 1997, boron was quoted at $280 per gram for polycrystalline 4 to 6 mm diameter rods of 99.999% purity, about ten times the then $28.35 per gram cost of gold.
*In 2020 phosphorus in its most stable black form could "cost up to $1,000 per gram",Boise State University 2020 more than 15 times the cost of gold, whereas ordinary red phosphorus, in 2017, was priced at about $3.40 per kilogram. Researchers hoped to be able to reduce the cost of black phosphorus to as low as $1 per gram.
*Germanium and xenon cost about $1.20 and $7.60 per gram.
*Up to 2013, radon was available from the
National Institute of Standards and Technology
The National Institute of Standards and Technology (NIST) is an agency of the United States Department of Commerce whose mission is to promote American innovation and industrial competitiveness. NIST's activities are organized into physical s ...
for $1,636 per 0.2 ml unit of issue, equivalent to about $86,000,000 per gram, with no indication of a discount for bulk quantities.
Shared uses
Nearly all nonmetals have varying uses in household items; lighting and lasers; and medicine and
pharmaceutical
A medication (also called medicament, medicine, pharmaceutical drug, medicinal drug or simply drug) is a drug used to diagnose, cure, treat, or prevent disease. Drug therapy ( pharmacotherapy) is an important part of the medical field and ...
s. Nitrogen, for example, is found in some garden treatments;
lasers
A laser is a device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation. The word "laser" is an acronym for "light amplification by stimulated emission of radiation". The fir ...
; and diabetes medicines. Germanium, arsenic, and radon each have uses in one or two of these fields but not all three. Aside from the noble gases most of the remaining nonmetals have, or have had, uses in
agrochemical
An agrochemical or agrichemical, a contraction of ''agricultural chemical'', is a chemical product used in industrial agriculture. Agrichemical refers to biocides ( pesticides including insecticides, herbicides, fungicides and nematicides) a ...
s and
dyestuff
A dye is a colored substance that chemically bonds to the substrate to which it is being applied. This distinguishes dyes from pigments which do not chemically bind to the material they color. Dye is generally applied in an aqueous solution and ...
s. To the extent that metalloids show metallic character, they have speciality uses extending to (for example) oxide glasses,
alloy
An alloy is a mixture of chemical elements of which at least one is a metal. Unlike chemical compounds with metallic bases, an alloy will retain all the properties of a metal in the resulting material, such as electrical conductivity, ductili ...
ing components, and semiconductors.
Further shared uses of different subsets of the nonmetals occur in or as air replacements;
cryogenics
In physics, cryogenics is the production and behaviour of materials at very low temperatures.
The 13th IIR International Congress of Refrigeration (held in Washington DC in 1971) endorsed a universal definition of “cryogenics” and “c ...
and
refrigerant
A refrigerant is a working fluid used in the refrigeration cycle of air conditioning systems and heat pumps where in most cases they undergo a repeated phase transition from a liquid to a gas and back again. Refrigerants are heavily regulated ...
s;
fertilizer
A fertilizer (American English) or fertiliser (British English; see spelling differences) is any material of natural or synthetic origin that is applied to soil or to plant tissues to supply plant nutrients. Fertilizers may be distinct from ...
s;
flame retardant
The term flame retardants subsumes a diverse group of chemicals that are added to manufactured materials, such as plastics and textiles, and surface finishes and coatings. Flame retardants are activated by the presence of an ignition source and ...
s or
fire extinguishers
A fire extinguisher is a handheld active fire protection device usually filled with a dry or wet chemical used to extinguish or control small fires, often in emergencies. It is not intended for use on an out-of-control fire, such as one which ha ...
;
mineral acids
A mineral acid (or inorganic acid) is an acid derived from one or more inorganic compounds, as opposed to organic acids which are acidic, organic compounds. All mineral acids form hydrogen ions and the conjugate base when dissolved in water.
Char ...
;
plug-in hybrid
A plug-in hybrid electric vehicle (PHEV) is a hybrid electric vehicle whose battery pack can be recharged by plugging a charging cable into an external electric power source, in addition to internally by its on-board internal combustion engin ...
smart phones
A smartphone is a portable computer device that combines mobile telephone and computing functions into one unit. They are distinguished from feature phones by their stronger hardware capabilities and extensive mobile operating systems, which ...
.
History, background, and taxonomy
Discovery
Most nonmetals were discovered in the 18th and 19th centuries. Before then carbon, sulfur and antimony were known in
antiquity
Antiquity or Antiquities may refer to:
Historical objects or periods Artifacts
*Antiquities, objects or artifacts surviving from ancient cultures
Eras
Any period before the European Middle Ages (5th to 15th centuries) but still within the histo ...
; arsenic was discovered during the
Middle Ages
In the history of Europe, the Middle Ages or medieval period lasted approximately from the late 5th to the late 15th centuries, similar to the post-classical period of global history. It began with the fall of the Western Roman Empire ...
(by
Albertus Magnus
Albertus Magnus (c. 1200 – 15 November 1280), also known as Saint Albert the Great or Albert of Cologne, was a German Dominican friar, philosopher, scientist, and bishop. Later canonised as a Catholic saint, he was known during his li ...
); and
Hennig Brand
Hennig Brand (; c. 1630c. 1692 or c. 1710) was a German alchemist who lived and worked in Hamburg. In 1669, Brand accidentally discovered the chemical element phosphorus while searching for the "philosopher's stone", a substance which was believed ...
isolated phosphorus from urine in 1669. Helium (1868) holds the distinction of being the only element not first discovered on Earth. Radon is the most recently discovered nonmetal, being found only at the end of the 19th century.
Chemistry- or physics-based techniques used in the isolation efforts were
spectroscopy
Spectroscopy is the field of study that measures and interprets the electromagnetic spectra that result from the interaction between electromagnetic radiation and matter as a function of the wavelength or frequency of the radiation. Matter ...
,
fractional distillation
Fractional distillation is the separation of a mixture into its component parts, or fractions. Chemical compounds are separated by heating them to a temperature at which one or more fractions of the mixture will vaporize. It uses distillation ...
electrolysis
In chemistry and manufacturing, electrolysis is a technique that uses direct electric current (DC) to drive an otherwise non-spontaneous chemical reaction. Electrolysis is commercially important as a stage in the separation of elements from n ...
, ore acidification,
displacement reaction
A chemical reaction is a process that leads to the chemical transformation of one set of chemical substances to another. Classically, chemical reactions encompass changes that only involve the positions of electrons in the forming and breaking ...
s,
combustion
Combustion, or burning, is a high-temperature exothermic redox chemical reaction between a fuel (the reductant) and an oxidant, usually atmospheric oxygen, that produces oxidized, often gaseous products, in a mixture termed as smoke. Combus ...
and heating; a few nonmetals occurred naturally as free elements
Of the noble gases, helium was detected via its yellow line in the coronal spectrum of the sun, and later by observing the bubbles escaping from
uranite
Uraninite, formerly pitchblende, is a radioactive, uranium-rich mineral and ore with a chemical composition that is largely UO2 but because of oxidation typically contains variable proportions of U3O8. Radioactive decay of the uranium causes t ...
UO2 dissolved in acid. Neon through xenon were obtained via
fractional distillation
Fractional distillation is the separation of a mixture into its component parts, or fractions. Chemical compounds are separated by heating them to a temperature at which one or more fractions of the mixture will vaporize. It uses distillation ...
of air. Radon was first observed emanating from compounds of
thorium
Thorium is a weakly radioactive metallic chemical element with the symbol Th and atomic number 90. Thorium is silvery and tarnishes black when it is exposed to air, forming thorium dioxide; it is moderately soft and malleable and has a high ...
, three years after
Henri Becquerel
Antoine Henri Becquerel (; 15 December 1852 – 25 August 1908) was a French engineer, physicist, Nobel laureate, and the first person to discover evidence of radioactivity. For work in this field he, along with Marie Skłodowska-Curie and Pie ...
's discovery of radiation in 1896.
The nonmetal halogens were obtained from their
halide
In chemistry, a halide (rarely halogenide) is a binary chemical compound, of which one part is a halogen atom and the other part is an element or radical that is less electronegative (or more electropositive) than the halogen, to make a flu ...
s via either
electrolysis
In chemistry and manufacturing, electrolysis is a technique that uses direct electric current (DC) to drive an otherwise non-spontaneous chemical reaction. Electrolysis is commercially important as a stage in the separation of elements from n ...
, adding an acid, or displacement. Some chemists died as a result of their experiments trying to isolate fluorine.
Among the unclassified nonmetals, carbon was known (or produced) as charcoal, soot, graphite and diamond; nitrogen was observed in air from which oxygen had been removed; oxygen was obtained by heating mercurous oxide; phosphorus was liberated by heating ammonium sodium hydrogen phosphate (Na(NH4)HPO4), as found in
urine
Urine is a liquid by-product of metabolism in humans and in many other animals. Urine flows from the kidneys through the ureters to the urinary bladder. Urination results in urine being excreted from the body through the urethra.
Cellul ...
; sulfur occurred naturally as a free element; and selenium was detected as a residue in
sulfuric acid
Sulfuric acid (American spelling and the preferred IUPAC name) or sulphuric acid ( Commonwealth spelling), known in antiquity as oil of vitriol, is a mineral acid composed of the elements sulfur, oxygen and hydrogen, with the molecular fo ...
.
Most of the elements commonly recognized as metalloids were isolated by heating their oxides (
boron
Boron is a chemical element with the symbol B and atomic number 5. In its crystalline form it is a brittle, dark, lustrous metalloid; in its amorphous form it is a brown powder. As the lightest element of the '' boron group'' it has t ...
,
silicon
Silicon is a chemical element with the symbol Si and atomic number 14. It is a hard, brittle crystalline solid with a blue-grey metallic luster, and is a tetravalent metalloid and semiconductor. It is a member of group 14 in the periodic ...
,
arsenic
Arsenic is a chemical element with the symbol As and atomic number 33. Arsenic occurs in many minerals, usually in combination with sulfur and metals, but also as a pure elemental crystal. Arsenic is a metalloid. It has various allotropes, b ...
,
tellurium
Tellurium is a chemical element with the symbol Te and atomic number 52. It is a brittle, mildly toxic, rare, silver-white metalloid. Tellurium is chemically related to selenium and sulfur, all three of which are chalcogens. It is occasionall ...
) or a sulfide (
germanium
Germanium is a chemical element with the symbol Ge and atomic number 32. It is lustrous, hard-brittle, grayish-white and similar in appearance to silicon. It is a metalloid in the carbon group that is chemically similar to its group neighbors ...
). Antimony was known in its native form as well as being attainable by heating its sulfide.
Origin of the concept
The distinction between
metal
A metal (from ancient Greek, Greek μέταλλον ''métallon'', "mine, quarry, metal") is a material that, when freshly prepared, polished, or fractured, shows a lustrous appearance, and conducts electrical resistivity and conductivity, e ...
s and nonmetals arose, in a convoluted manner, from a crude recognition of different kinds of matter namely pure substances, mixtures, compounds and elements. Thus, matter could be divided into pure substances (such as salt, bicarb of soda, or sulfur) and mixtures ( aqua regia,
gunpowder
Gunpowder, also commonly known as black powder to distinguish it from modern smokeless powder, is the earliest known chemical explosive. It consists of a mixture of sulfur, carbon (in the form of charcoal) and potassium nitrate (saltpeter). T ...
, or
bronze
Bronze is an alloy consisting primarily of copper, commonly with about 12–12.5% tin and often with the addition of other metals (including aluminium, manganese, nickel, or zinc) and sometimes non-metals, such as phosphorus, or metalloids suc ...
, for example) and pure substances eventually could be distinguished as compounds and elements. "Metallic" elements then seemed to have broadly distinguishable attributes that other elements did not, such as their ability to conduct heat or for their " earths" (
oxide
An oxide () is a chemical compound that contains at least one oxygen atom and one other element in its chemical formula. "Oxide" itself is the dianion of oxygen, an O2– (molecular) ion. with oxygen in the oxidation state of −2. Most of the E ...
s) to form
basic
BASIC (Beginners' All-purpose Symbolic Instruction Code) is a family of general-purpose, high-level programming languages designed for ease of use. The original version was created by John G. Kemeny and Thomas E. Kurtz at Dartmouth College ...
solutions in water, for example as occurred with
quicklime
Calcium oxide (CaO), commonly known as quicklime or burnt lime, is a widely used chemical compound. It is a white, caustic, alkaline, crystalline solid at room temperature. The broadly used term "'' lime''" connotes calcium-containing inorganic m ...
(CaO).
Use of the term
The term ''nonmetallic'' dates from as far back as 1566. In a medical treatise published that year, Loys de L’Aunay (a French doctor) mentioned the properties of plant substances from metallic and "non-metallic" lands.
In early chemistry, Wilhelm Homberg (a German natural philosopher) referred to "non-metallic" sulfur in ''
Des Essais de Chimie
Des is a masculine given name, mostly a short form (hypocorism) of Desmond. People named Des include:
People
* Des Buckingham, English football manager
* Des Corcoran, (1928–2004), Australian politician
* Des Dillon (disambiguation), severa ...
'' (1708). He questioned the five-fold division of all matter into sulfur, mercury, salt, water and earth, as postulated by (1641) in ''
New Philosophical Light of True Principles and Elements of Nature
New is an adjective referring to something recently made, discovered, or created.
New or NEW may refer to:
Music
* New, singer of K-pop group The Boyz
Albums and EPs
* ''New'' (album), by Paul McCartney, 2013
* ''New'' (EP), by Regurgitator, ...
.'' Homberg's approach represented "an important move toward the modern concept of an element".
Lavoisier
Antoine-Laurent de Lavoisier ( , ; ; 26 August 17438 May 1794), CNRS ( Traité élémentaire de chimie,'' published the first modern list of chemical elements in which he distinguished between gases, metals, nonmetals, and earths (heat resistant oxides). In its first seventeen years, Lavoisier's work was republished in twenty-three editions in six languages, and "carried ... isnew chemistry all over Europe and America."
Suggested distinguishing criteria
In 1809,
Humphry Davy
Sir Humphry Davy, 1st Baronet, (17 December 177829 May 1829) was a British chemist and inventor who invented the Davy lamp and a very early form of arc lamp. He is also remembered for isolating, by using electricity, several elements for ...
's discovery of
sodium
Sodium is a chemical element with the symbol Na (from Latin ''natrium'') and atomic number 11. It is a soft, silvery-white, highly reactive metal. Sodium is an alkali metal, being in group 1 of the periodic table. Its only stable ...
and
potassium
Potassium is the chemical element with the symbol K (from Neo-Latin '' kalium'') and atomic number19. Potassium is a silvery-white metal that is soft enough to be cut with a knife with little force. Potassium metal reacts rapidly with atmos ...
"annihilated" the line of demarcation between metals and nonmetals. Before then metals had been distinguished on the basis of their ponderousness or relatively high densities. Sodium and potassium, on the other hand, floated on water and yet were clearly metals on the basis of their chemical behaviour.
From as early as 1811, different properties—physical, chemical, and electron related—have been used in attempts to refine the distinction between metals and nonmetals. The accompanying table sets out 22 such properties, by type and date order.
Probably the most well-known property is that the electrical conductivity of a metal increases when temperature falls whereas that of a non-metal rises. However this scheme does not work for
plutonium
Plutonium is a radioactive chemical element with the symbol Pu and atomic number 94. It is an actinide metal of silvery-gray appearance that tarnishes when exposed to air, and forms a dull coating when oxidized. The element normally exh ...
, carbon, arsenic and antimony. Plutonium, which is a metal, increases its electrical conductivity when heated in the temperature range of around –175 to +125 °C. Carbon, despite being widely regarded as a nonmetal, likewise increases its conductivity when heated. Arsenic and antimony are sometimes classified as nonmetals yet act similarly to carbon.
Kneen et al. suggested that the nonmetals could be discerned once a [single] criterion for metallicity had been chosen, adding that, "many arbitrary classifications are possible, most of which, if chosen reasonably, would be similar but not necessarily identical." Emsley noted that, "No single property... can be used to classify all the elements as either metals or nonmetals." Jones added that "classes are usually defined by more than two attributes".
Johnson suggested that physical properties can best indicate the metallic or nonmetallic properties of an element, with the proviso that other properties will be needed in ambiguous cases. He observed that all gaseous or nonconducting elements are nonmetals; solid nonmetals metals are hard and brittle or soft and crumbly whereas metals are usually malleable and ductile; and nonmetal oxides are acidic.
According to Hein and Arena, nonmetals have low densities and relatively high electronegativity; the accompanying table bears this out. Nonmetallic elements occupy the top left quadrant, where densities are low and electronegativity values are relatively high. The other three quadrants are occupied by metals. Some authors further divide the elements into metals,
metalloids
A metalloid is a type of chemical element which has a preponderance of properties in between, or that are a mixture of, those of metals and nonmetals. There is no standard definition of a metalloid and no complete agreement on which elements are ...
, and nonmetals although Odberg argues that anything not a metal is, on ontology, categorisation grounds, a nonmetal.
Development of subclasses
A basic taxonomy of nonmetals was set out in 1844, by Alphonse Dupasquier, a French doctor, pharmacist and chemist. To facilitate the study of nonmetals, he wrote:
:They will be divided into four groups or sections, as in the following:
::Organogens O, N, H, C
::Sulphuroids S, Se, P
::Chloroides F, Cl, Br, I
::Boroids B, Si.
An echo of Dupasquier's fourfold classification is seen in the modern subclasses. The organogens and sulphuroids represent the set of unclassified nonmetals. Varying configurations of these seven nonmetals have been referred to as, for example, basic nonmetals; biogens; central nonmetals; CHNOPS; essential elements; "nonmetals"; orphan nonmetals; or redox nonmetals.
The chloroide nonmetals came to be independently referred to as ''halogens.'' The boroid nonmetals expanded into the ''metalloids'', starting from as early as 1864. The noble gases, as a discrete grouping, were counted among the nonmetals from as early as 1900.
Comparison
Some properties of metals, and of metalloids, unclassified nonmetals, nonmetal halogens, and noble gases are summarized in the table. Physical properties apply to elements in their most stable forms in ambient conditions, and are listed in loose order of ease of determination. Chemical properties are listed from general to descriptive, and then to specific. The dashed line around the metalloids denotes that, depending on the author, the elements involved may or may not be recognized as a distinct class or subclass of elements. Metals are included as a reference point.
Most properties show a left-to-right progression in metallic to nonmetallic character or average values. The periodic table can thus be indicatively divided into metals and nonmetals, with more or less distinct gradations seen among the nonmetals.#Vernon2020, Vernon 2020, pp. 217–225
See also
* CHON (carbon, hydrogen, oxygen, nitrogen)
* List of nonmetal monographs
* Metallization pressure
* Period 1 elements (hydrogen, helium)
* Properties of nonmetals (and metalloids) by group
Notes
References
Citations
Bibliography
* Abbott D 1966, ''An Introduction to the Periodic Table,'' J. M. Dent & Sons, London
* Atkins PA 2001, ''The Periodic Kingdom: A Journey Into the Land of the Chemical Elements'', Phoenix, London,
* Atkins PA et al. 2006, ''Shriver & Atkins' Inorganic Chemistry'', 4th ed., Oxford University Press, Oxford,
* Atkins PA & Overton T 2010, ''Shriver & Atkins' Inorganic Chemistry'', 5th ed., Oxford University Press, Oxford,
*Aylward G and Findlay T 2008, ''SI Chemical Data,'' 6th ed., John Wiley & Sons Australia, Milton,
* Bailar JC et al. 1989, ''Chemistry'', 3rd ed., Harcourt Brace Jovanovich, San Diego,
* Barton AFM 2021, ''States of Matter, States of Mind,'' CRC Press, Boca Raton,
* Beach FC (ed.) 1911, ''The Americana: A universal reference library,'' vol. XIII, Mel–New, Metalloid, Scientific American Compiling Department, New York
* Benner SA, Ricardo A & Carrigan MA 2018, "Is there a common chemical model for life in the universe?", in Cleland CE & Bedau MA (eds.), ''The Nature of Life: Classical and Contemporary Perspectives from Philosophy and Science'', Cambridge University Press, Cambridge,
* Berger LI 1997, ''Semiconductor Materials, ''CRC Press, Boca Raton,
* 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,
* Berzelius JJ & Bache AD 1832, "An essay on chemical nomenclature, prefixed to the treatise on chemistry", ''The American Journal of Science and Arts'', vol. 22
* Bodner GM & Pardue HL 1993, ''Chemistry, An Experimental Science'', John Wiley & Sons, New York,
* 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,
* Boise State University 2020 "Cost-effective manufacturing methods breathe new life into black phosphorus research" Micron School of Materials Science and Engineering, accessed July 9, 2021
* Borg RG & Dienes GJ 1992, ''The Physical Chemistry of Solids,'' Academic Press, Boston,
* Boyd R 2011, "Selenium stories", ''Nature Chemistry'', vol. 3,
* Brady JE & Senese F 2009, ''Chemistry: The study of Matter and its Changes'', 5th ed., John Wiley & Sons, New York,
* Brande WT 1821, ''A Manual of Chemistry,'' vol. II, John Murray, London
* Brodsky MH, Gambino RJ, Smith JE Jr & Yacoby Y 1972, "The Raman spectrum of amorphous tellurium", ''Physica Status Solidi B'', vol. 52,
* Brown TL et al. 2014, ''Chemistry: The Central Science,'' 3rd ed., Pearson Australia: Sydney,
* Burford N, Passmore J & Sanders JCP 1989, "The preparation, structure, and energetics of homopolyatomic cations of groups 16 (the chalcogens) and 17 (the halogens), in Liebman JF & Greenberg A, ''From atoms to polymers : isoelectronic analogies,'' VCH: New York,
* Cacace F, de Petris G & Troiani A 2002, "Experimental detection of tetranitrogen", ''Science'', vol. 295, no. 5554,
* Cao C et al. 2021, "Understanding periodic and non-periodic chemistry in periodic tables", ''Frontiers in Chemistry'', vol. 8, no. 813,
* 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 NC Norman (ed.), ''Chemistry of Arsenic, Antimony and Bismuth'', Blackie Academic & Professional, London, pp. 1–38,
* Challoner J 2014, ''The Elements: The New Guide to the Building Blocks of our Universe'', Carlton Publishing Group,
* 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,
* 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,
* Chemical Abstracts Service 2021 CAS REGISTRY database as of November 2, Talk:Nonmetal#Chemical Abstracts Service top 20 list of elements found in compounds, Case #01271182
* Cherim SM 1971, ''Chemistry for Laboratory Technicians'', Saunders, Philadelphia,
* Chung DD 1987, "Review of exfoliated graphite", ''Journal of Materials Science'', vol. 22,
* Clugston MJ & Flemming R 2000, ''Advanced Chemistry'', Oxford University Press, Oxford,
* Cockell C 2019, ''The Equations of Life: How Physics Shapes Evolution,'' Atlantic Books, London,
* 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,
* 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,
* Cox AN (ed.) 2000, ''Allen's Astrophysical Quantities'', 4th ed., AIP Press, New York,
* Cox PA 1997, ''The Elements: Their Origins, Abundance, and Distribution'', Oxford University Press, Oxford,
* Cox T 2004, ''Inorganic Chemistry'', 2nd ed., BIOS Scientific Publishers, London,
* 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,
* 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,
* 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,
* de Clave E 1641, New Philosophical Light of True Principles and Elements of Nature '' Olivier Devarennes, Paris, accessed February 24, 2022
* 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
* Desai PD, James HM & Ho CY 1984 "Electrical Resistivity of Aluminum and Manganese" ''Journal of Physical and Chemical Reference Data'', vol. 13, no. 4,
* Dingle A 2017, ''The Elements: An Encyclopedic Tour of the Periodic Table,'' Quad Books, Brighton,
* Donohue J 1982, ''The Structures of the Elements'', Robert E. Krieger, Malabar, Florida,
* 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,
* Dupasquier A 1844, ''Traité élémentaire de chimie industrielle'', Charles Savy Juene, Lyon.
* Ebbing DD & Gammon SD 2007, ''General Chemistry,'' 9th ed., Houghton Miffllin, Boston,
* 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,
* Edwards PP 2000, "What, why and when is a metal?", in Hall N (ed.), ''The New Chemistry'', Cambridge University, Cambridge, pp. 85–114,
* 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,
* 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, ,
* Elatresh SF & Bonev SA 2020, "Stability and metallization of solid oxygen at high pressure", ''Physical Chemistry Chemical Physics'', vol. 22, no. 22,
* Emsley J 1971, ''The Inorganic Chemistry of the Non-metals'', Methuen Educational, London,
* Emsley J 2011 ''Nature's Building Blocks: An A–Z Guide to the Elements'' Oxford University Press, Oxford,
* ''Encyclopædia Britannica'' 2021 Periodic table accessed September 21, 2021
* Errandonea D 2020, "Pressure-induced phase transformations," ''Crystals,'' vol. 10,
* 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
* 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,
* Fortescue JAC 2012, ''Environmental Geochemistry: A Holistic Approach,'' Springer-Verlag, New York,
* 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,
* Gaffney J & Marley N 2017, ''General Chemistry for Engineers'', Elsevier, Amsterdam,
* Gargaud M et al. (eds.) 2006, ''Lectures in Astrobiology, vol. 1, part 1: The Early Earth and Other Cosmic Habitats for Life'', Springer, Berlin,
* Glinka N 1958, ''General chemistry'', Sobolev D (trans.), Foreign Languages Publishing House, 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,
*Godovikov AA & Nenasheva N 2020, ''Structural-chemical Systematics of Minerals,'' 3rd ed., Springer, Cham, Switzerland,
* 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,
* Grochala W 2018, "On the position of helium and neon in the Periodic Table of Elements", ''Foundations of Chemistry,'' vol. 20, pp. 191–207,
* Gusmão R, Sofer Z & Pumera M 2017, "Black phosphorus rediscovered: From bulk material to monolayers", ''Angewandte Chemie International Edition'', vol. 56, no. 28,
* Hampel CA & Hawley GG 1976, ''Glossary of Chemical Terms'', Van Nostrand Reinhold, New York,
* 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,
* 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
* Hengeveld R & Fedonkin MA 2007, "Bootstrapping the energy flow in the beginning of life", ''Acta Biotheoretica,'' vol. 55,
* 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,
* Hermann A, Hoffmann R & Ashcroft NW 2013, "Condensed Astatine: Monatomic and metallic", ''Physical Review Letters'', vol. 111,
* 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,
* Herzfeld K 1927, "On atomic properties which make an element a metal", ''Physical Review'', vol. 29, no. 5,
* Hill G & Holman J 2000 ''Chemistry in Context'' 5th ed., Nelson Thornes, Cheltenham,
* Hill G, Holman J & Hulme PG 2017, ''Chemistry in Context,'' 7th ed., Oxford University Press, Oxford,
* Holderness A & Berry M 1979, ''Advanced Level Inorganic Chemistry'', 3rd ed., Heinemann Educational Books, London,
* Höll, Kling & Schroll E 2007, "Metallogenesis of germanium—A review", ''Ore Geology Reviews,'' vol. 30, nos. 3–4, pp. 145–180,
* Homberg W 1708, "Des Essais de Chimie", in ''Histoire De L'Academie Royale Des Sciences: Avec les Memoires de Mathematique & de Physique,'' L'Académie, Paris
* Horvath AL 1973, "Critical temperature of elements and the periodic system", ''Journal of Chemical Education,'' vol. 50, no. 5,
* House JE 2008, ''Inorganic Chemistry'', Elsevier, Amsterdam,
* Housecroft CE & Sharpe AG 2008, ''Inorganic Chemistry,'' 3rd ed., Prentice-Hall, Harlow,
* Hurlbut Jr CS 1961, ''Manual of Mineralogy'', 15th ed., John Wiley & Sons, New York
* 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,
* Jenkins GM & Kawamura K 1976, ''Polymeric Carbons—Carbon Fibre, Glass and Char'', Cambridge University Press, Cambridge,
* 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,
* Johnson D (ed.) 2007, ''Metals and Chemical Change,'' RSC Publishing, Cambridge,
* 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,
* Kaiho T 2017, ''Iodine Made Simple'', CRC Press, e-book,
* Keeler J & Wothers P 2013, ''Chemical Structure and Reactivity: An Integrated Approach'', Oxford University Press, Oxford,
* Kendall EA 1811, ''Pocket encyclopædia,'' 2nd ed., vol. III, Longman, Hurst, Rees, Orme, and Co., London
* Khan N 2001, ''An Introduction to Physical Geography,'' Concept Publishing, New Delhi,
* Kim MG 2000, "Chemical analysis and the domains of reality: Wilhelm Homberg's Essais de chimie, 1702–1709", ''Studies in History and Philosophy of Science Part A,'' vol. 31, no. 1, pp. 37–69,
* King RB 1994, ''Encyclopedia of Inorganic Chemistry'', vol. 3, John Wiley & Sons, New York,
* King RB 1995, ''Inorganic Chemistry of Main Group Elements'', VCH, New York,
* 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,
* Kneen WR, Rogers MJW & Simpson P 1972, ''Chemistry: Facts, Patterns, and Principles'', Addison-Wesley, London,
* Knight J 2002, ''Science of Everyday Things: Real-life chemistry'', Gale Group, Detroit,
* 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,
* Koziel JA 2002, "Sampling and sample preparation for indoor air analysis", in Pawliszyn J (ed.), ''Comprehensive Analytical Chemistry'', vol. 37, Elsevier Science B.V., Amsterdam,
* Kubaschewski O 1949, "The change of entropy, volume and binding state of the elements on melting", ''Transactions of the Faraday Society,'' vol. 45,
* 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,
* 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,
* Larrañaga MD, Lewis RJ & Lewis RA 2016, ''Hawley's Condensed Chemical Dictionary,'' 16th ed., Wiley, Hoboken, New York,
* Lee JD 1996, ''Concise Inorganic Chemistry'', 5th ed., Blackwell Science, Oxford,
* Lewis RJ 1993, ''Hawley's Condensed Chemical Dictionary'', 12th ed., Van Nostrand Reinhold, New York,
* Lidin RA 1996, ''Inorganic Substances Handbook'', Begell House, New York,
* Liptrot GF 1983, ''Modern Inorganic Chemistry'', 4th ed., Bell & Hyman,
* Los Alamos National Laboratory 2021, Periodic Table of Elements: A Resource for Elementary, Middle School, and High School Students ', accessed September 19, 2021
* Luchinskii GP & Trifonov DN 1981, "Some problems of chemical elements classification and the structure of the periodic system", in ''Uchenie o Periodichnosti. Istoriya i Sovremennoct'', (Russian) Nauka, Moscow
* MacKay KM, MacKay RA & Henderson W 2002, ''Introduction to Modern Inorganic Chemistry'', 6th ed., Nelson Thornes, Cheltenham,
* Mackin M 2014, ''Study Guide to Accompany Basics for Chemistry'', Elsevier Science, Saint Louis,
* Maosheng M 2020, "Noble gases in solid compounds show a rich display of chemistry with enough pressure", ''Frontiers in Chemistry'', vol. 8,
* Massey AG 2000, ''Main group chemistry,'' 2nd ed., John Wiley & Sons, Chichester,
* Masterton W, Hurley C & Neth E 2011, ''Chemistry: Principles and Reactions'', 7th ed., Brooks/Cole, Belmont, California,
* Matson M & Orbaek AW 2013, ''Inorganic Chemistry for Dummies,'' John Wiley & Sons: Hoboken,
* Matula RA 1979, "Electrical resistivity of copper, gold, palladium, and silver", ''Journal of Physical and Chemical Reference Data'', vol. 8, no. 4,
* 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, , ,
* 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,
* Messler Jr RW 2011, ''The Essence of Materials for Engineers'', Jones and Bartlett Learning, Sudbury, Massachusetts,
* Mewes et al. 2019, Copernicium: A relativistic noble liquid, ''Angewandte Chemie International Edition,'' vol. 58, pp. 17964–17968,
* 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,
* Moeller T et al. 2012, ''Chemistry: With Inorganic Qualitative Analysis'', Academic Press, New York,
* Möller D 2003, ''Luft: Chemie, Physik, Biologie, Reinhaltung, Recht'', Walter de Gruyter, Berlin,
* Moody B 1991, ''Comparative Inorganic Chemistry'', 3rd ed., Edward Arnold, London,
* Moore JT 2016, ''Chemistry for Dummies,'' 2nd ed., ch. 16, Tracking periodic trends, John Wiley & Sons: Hoboken,
* Morita A 1986, 'Semiconducting Black Phosphorus', ''Journal of Applied Physics A,'' vol. 39, no. 4, pp. 227–42,
* 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
* Nakao Y 1992, "Dissolution of noble metals in halogen–halide–polar organic solvent systems", ''Journal of the Chemical Society, Chemical Communications'', no. 5,
* National Center for Biotechnology Information 2021, PubChem compound summary for CID 402, Hydrogen sulfide , accessed August 31, 2021
* National Institute of Standards and Technology 2013, SRM 4972 – Radon-222 Emanation Standard ', accessed August 1, 2021
* Nelson PG 1987, "Important elements", ''Journal of Chemical Education'', vol. 68, no. 9,
* Oderberg DS 2007, Real Essentialism ', Routledge, New York,
* Ostriker JP & Steinhardt PJ 2001, "The quintessential universe", ''Scientific American'', vol. 284, no. 1, pp. 46–53 ,
* Oxtoby DW, Gillis HP & Butler LJ 2015, ''Principles of Modern Chemistry'', 8th ed., Cengage Learning, Boston,
* 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,
* Parish RV 1977, ''The Metallic Elements'', Longman, London,
* Partington JR 1944, ''A Text-book of Inorganic Chemistry'', 5th ed., Macmillan & Co., London
*Petruševski VM & Cvetković J 2018, "On the 'true position' of hydrogen in the Periodic Table", ''Foundations of Chemistry,'' vol. 20, pp. 251–260,
* 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,
* Piro NA et al. 2006, "Triple-bond reactivity of diphosphorus molecules", ''Science'', vol. 313, no. 5791, ,
* Pitzer K 1975, "Fluorides of radon and elements 118", ''Journal of the Chemical Society, Chemical Communications'', no. 18,
* Porterfield WW 1993, ''Inorganic chemistry'', Academic Press, San Diego,
* Povh B & Rosina M 2017, ''Scattering and Structures: Essentials and Analogies in Quantum Physics,'' 2nd ed., Springer, Berlin,
* Powell P & Timms P 1974, ''The Chemistry of the Non-Metals,'' Chapman and Hall, London,
* Puddephatt RJ & Monaghan PK 1989, ''The Periodic Table of the Elements'', 2nd ed., Clarendon Press, Oxford,
* 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,
* Rao KY 2002, ''Structural Chemistry of Glasses'', Elsevier, Oxford,
* Rao CNR & Ganguly PA 1986, "New criterion for the metallicity of elements", ''Solid State Communications,'' vol. 57, no. 1, pp. 5–6,
* Rayner-Canham G 2018, "Organizing the transition metals", in Scerri E & Restrepo G, ''Mendeleev to Oganesson: A multidisciplinary perspective on the periodic table'', Oxford University, New York,
* Rayner-Canham G 2020, ''The Periodic Table: Past, Present and Future'', World Scientific, New Jersey,
* Regnault MV 1853, ''Elements of Chemistry'', vol. 1, 2nd ed., Clark & Hesser, Philadelphia
* Reilly C 2002, ''Metal Contamination of Food'', Blackwell Science, Oxford,
* 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,
* Restrepo G, Llanos EJ & Mesa H 2006, "Topological space of the chemical elements and its properties", ''Journal of Mathematical Chemistry'', vol. 39,
* Ritter SK 2011 ''Chemical & Engineering News'', vol. 89, no. 9,
* Rochow EG 1966, ''The Metalloids'', DC Heath and Company, Boston
* Rochow EG 1973, "Silicon", in Bailar JC et al. (eds.), ''Comprehensive Inorganic Chemistry,'' vol. 1, Pergamon Press, Oxford,
* Rodgers GE 2012, ''Descriptive Inorganic, Coordination, and Solid State Chemistry'', 3rd ed., Brooks/Cole, Belmont, California,
* Royal Society of Chemistry 2021 Periodic Table: Non-metal accessed September 3, 2021
* Rudolph J 1973, Chemistry for the Modern Mind ', Macmillan, New York
* Russell AM & Lee KL 2005 ''Structure-Property Relations in Nonferrous Metals'' Wiley-Interscience, New York,
* Salinas JT 2019 ''Exploring Physical Science in the Laboratory,'' Moreton Publishing, Englewood, Colorado,
* Salzberg HW 1991, ''From Caveman to Chemist: Circumstances and Achievements,'' American Chemical Society, Washington, DC,
* Sanderson RT 1957, "An electronic distinction between metals and nonmetals", ''Journal of Chemical Education,'' vol. 34, no. 5,
* 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,
* 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,
* 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,
* Scott D 2014, ''Around the World in 18 Elements'', Royal Society of Chemistry, e-book,
* Scott EC & Kanda FA 1962, ''The Nature of Atoms and Molecules: A General Chemistry'', Harper & Row, New York
* Seese WS & Daub GH 1985, ''Basic Chemistry'', 4th ed., Prentice-Hall, Englewood Cliffs, NJ,
* Segal BG 1989, ''Chemistry: Experiment and Theory,'' 2nd ed., John Wiley & Sons, New York,
* 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,
* Shang et al. 2021, "Ultrahard bulk amorphous carbon from collapsed fullerene", ''Nature'', vol. 599, pp. 599–604,
* Sherwin E & Weston GJ 1966, ''Chemistry of the Non-metallic Elements'', Pergamon Press, Oxford
* Shiell et al. 2021, "Bulk crystalline 4H-silicon through a metastable allotropic transition", ''Physical Review Letters'', vol. 26, p 215701,
* 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,
* Sidorov TA 1960, "The connection between structural oxides and their tendency to glass formation", ''Glass and Ceramics'', vol. 17, no. 11,
* Siekierski S & Burgess J 2002, ''Concise Chemistry of the Elements'', Horwood Press, Chichester,
* Smith A & Dwyer C 1991, ''Key Chemistry: Investigating Chemistry in the Contemporary World: Book 1: Materials and Everyday Life,'' Melbourne University Press, Carlton, Victoria,
* 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,
* Stein L 1969, "Oxidized radon in halogen fluoride solutions", ''Journal of the American Chemical Society'', vol. 19, no. 19,
* Stein L 1983, "The chemistry of radon", ''Radiochimica Acta'', vol. 32,
* Steudel R 1977, ''Chemistry of the Non-metals: With an Introduction to atomic Structure and Chemical Bonding'', Walter de Gruyter, Berlin,
* Steudel R & Eckert B 2003, "Solid sulfur allotropes", in Steudel R (ed.), ''Elemental Sulfur and Sulfur-rich Compounds I'', Springer-Verlag, Berlin,
* Steudel R 2020, ''Chemistry of the Non-metals: Syntheses - Structures - Bonding - Applications'', in collaboration with D Scheschkewitz, Berlin, Walter de Gruyter,
* Still B 2016 ''The secret life of the periodic table,'' Cassell, London,
* Stott RWA 1956, ''Companion to Physical and Inorganic Chemistry,'' Longmans, Green and Co, London
* Stuke J 1974, 'Optical and electrical properties of selenium', in RA Zingaro & WC Cooper (eds), ''Selenium,'' Van Nostrand Reinhold, New York, pp. 174
* Strathern P 2000, ''Mendeleyev's dream: The Quest for the Elements,'' Hamish Hamilton, London,
* Su et al. 2020, "Advances in photonics of recently developed Xenes", ''Nanophotonics'', vol. 9, no. 7,
* Suresh CH & Koga NA 2001, "A consistent approach toward atomic radii”, ''Journal of Physical Chemistry A,'' vol. 105, no. 24.
* Tang et al. 2021, "Synthesis of paracrystalline diamond", ''Nature'', vol. 599, pp. 605–610,
* 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,
* 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
* Thornton BF & Burdette SC 2010, Finding eka-iodine: Discovery priority in modern times , ''Bulletin for the history of chemistry'', vol. 35, no. 2, accessed September 14, 2021
* Tregarthen L 2003, ''Preliminary Chemistry,'' Macmillan Education: Melbourne,
* Trenberth KE & Smith L 2005 "The mass of the atmosphere: A constraint on global analyses" ''Journal of Climate'', vol. 18, no. 6,
* Tshitoyan et al. 2019, "Unsupervised word embeddings capture latent knowledge from materials science literature", ''Nature'', vol. 571,
* Tyler PM 1948, ''From the Ground Up: Facts and Figures of the Mineral Industries of the United States'', McGraw-Hill, New York
* 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,
* Vernon R 2013, "Which elements are metalloids?", ''Journal of Chemical Education'', vol. 90, no. 12, 1703‒1707,
* Vernon R 2020, "Organising the metals and nonmetals", ''Foundations of Chemistry'', vol. 22, (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,
* Wakeman TH 1899, Free thought—Past, present and future , ''Free Thought Magazine'', vol. 17
* 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,
* Weeks ME 1945, ''Discovery of the Elements'', 5th ed., Journal of Chemical Education, Easton, Pennsylvania
* Welcher SH 2001, ''High marks: Regents Chemistry Made Easy'', 2nd ed., High Marks Made Easy, New York,
* Wells AF 1984, ''Structural Inorganic Chemistry'', 5th ed., Clarendon Press, Oxford,
* White JH 1962, ''Inorganic Chemistry: Advanced and Scholarship Levels'', University of London Press, London
* Wiberg N 2001, Inorganic Chemistry ', Academic Press, San Diego,
* Williams RPJ 2007, "Life, the environment and our ecosystem", ''Journal of Inorganic Biochemistry'', vol. 101, nos. 11–12,
* Woodward et al. 1999, "The electronic structure of metal oxides", In Fierro JLG (ed.), ''Metal Oxides: Chemistry and Applications'', CRC Press, Boca Raton,
* Wulfsberg G 1987, ''Principles of Descriptive Chemistry'', Brooks/Cole, Belmont CA,
* Wulfsberg G 2000, ''Inorganic Chemistry'', University Science Books, Sausalito, California,
* Yamaguchi M & Shirai Y 1996, "Defect structures", in Stoloff NS & Sikka VK (eds.), ''Physical Metallurgy and Processing of Intermetallic Compounds'', Chapman & Hall, New York,
* 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, ,
* Yoder CH, Suydam FH & Snavely FA 1975, ''Chemistry'', 2nd ed, Harcourt Brace Jovanovich, New York,
* Young JA 2006, "Iodine", ''Journal of Chemical Education'', vol. 83, no. 9,
* Young et al. 2018, ''General Chemistry: Atoms First,'' Cengage Learning: Boston,
* Yousuf M 1998, "Diamond anvil cells in high-pressure studies of semiconductors", in Suski T & Paul W (eds.), ''High Pressure in Semiconductor Physics II'', Semiconductors and Semimetals, vol. 55, Academic Press, San Diego,
* 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,
* Zhao Z, Zhang H, Kim D. et al. 2017, "Properties of the exotic metastable ST12 germanium allotrope", ''Nature Communications'', vol. 8, article no. 13909, , ,
* Zhigal'skii GP & Jones BK 2003, ''The Physical Properties of Thin Metal Films,'' Taylor & Francis, London,
* Zhu et al. 2014, "Reactions of xenon with iron and nickel are predicted in the Earth's inner core", ''Nature Chemistry'', vol. 6, ,
* Zumdahl SS & DeCoste DJ 2010, ''Introductory Chemistry: A Foundation,'' 7th ed., Cengage Learning, Mason, Ohio,