Nonmetal. In the context of the periodic table a nonmetal is a chemical element that mostly lacks distinctive metallic properties. They range from colorless gases like hydrogen to shiny crystals like iodine. Physically, they are usually lighter (less dense) than elements that form metals and are often poor conductors of heat and electricity. Chemically, nonmetals have relatively high electronegativity or usually attract electrons in a chemical bond with another element, and their oxides tend to be acidic.

Seventeen elements are widely recognized as nonmetals. Additionally, some or all of six borderline elements (metalloids) are sometimes counted as nonmetals.

The two lightest nonmetals, hydrogen and helium, together make up about 98% of the mass of the observable universe. Five nonmetallic elements—hydrogen, carbon, nitrogen, oxygen, and silicon—make up the bulk of Earth's atmosphere, biosphere, crust and oceans.

Industrial uses of nonmetals include in electronics, energy storage, agriculture, and chemical production.

Most nonmetallic elements were identified in the 18th and 19th centuries. While a distinction between metals and other minerals had existed since antiquity, a basic classification of chemical elements as metallic or nonmetallic emerged only in the late 18th century. Since then about twenty properties have been suggested as criteria for distinguishing nonmetals from metals.

Definition and applicable elements
Unless otherwise noted, this article describes the stable form of an element at standard temperature and pressure (STP).

Nonmetallic chemical elements are often described as lacking properties common to metals, namely shininess, pliability, good thermal and electrical conductivity, and a general capacity to form basic oxides. There is no widely accepted precise definition; any list of nonmetals is open to debate and revision. The elements included depend on the properties regarded as most representative of nonmetallic or metallic character.

Fourteen elements are almost always recognized as nonmetals:

Three more are commonly classed as nonmetals, but some sources list them as "metalloids", a term which refers to elements regarded as intermediate between metals and nonmetals:

One or more of the six elements most commonly recognized as metalloids are sometimes instead counted as nonmetals: 

About 15–20% of the 118 known elements are thus classified as nonmetals.

General properties

Physical

Nonmetals vary greatly in appearance, being colorless, colored or shiny.
For the colorless nonmetals (hydrogen, nitrogen, oxygen, and the noble gases), no absorption of light happens in the visible part of the spectrum, and all visible light is transmitted.
The colored nonmetals (sulfur, fluorine, chlorine, bromine) absorb some colors (wavelengths) and transmit the complementary or opposite colors. For example, chlorine's "familiar yellow-green colour ... is due to a broad region of absorption in the violet and blue regions of the spectrum". The shininess of boron, graphite (carbon), silicon, black phosphorus, germanium, arsenic, selenium, antimony, tellurium, and iodine is a result of varying degrees of metallic conduction where the electrons can reflect incoming visible light.

About half of nonmetallic elements are gases under standard temperature and pressure; most of the rest are solids. Bromine, the only liquid, is usually topped by a layer of its reddish-brown fumes. The gaseous and liquid nonmetals have very low densities, melting and boiling points, and are poor conductors of heat and electricity. The solid nonmetals have low densities and low mechanical strength (being either hard and brittle, or soft and crumbly), and a wide range of electrical conductivity.

This diversity in form stems from variability in internal structures and bonding arrangements. Covalent nonmetals existing as discrete atoms like xenon, or as small molecules, such as oxygen, sulfur, and bromine, have low melting and boiling points; many are gases at room temperature, as they are held together by weak London dispersion forces acting between their atoms or molecules, although the molecules themselves have strong covalent bonds. In contrast, nonmetals that form extended structures, such as long chains of selenium atoms, sheets of carbon atoms in graphite, or three-dimensional lattices of silicon atoms have higher melting and boiling points, and are all solids, as it takes more energy to overcome their stronger bonding. Nonmetals closer to the left or bottom of the periodic table (and so closer to the metals) often have metallic interactions between their molecules, chains, or layers; this occurs in boron, carbon, phosphorus, arsenic, selenium, antimony, tellurium and iodine.

Covalently bonded nonmetals often share only the electrons required to achieve a noble gas electron configuration. For example, nitrogen forms diatomic molecules featuring a triple bonds between each atom, both of which thereby attain the configuration of the noble gas neon. Antimony's larger atomic size prevents triple bonding, resulting in buckled layers in which each antimony atom is singly bonded with three other nearby atoms.

Good electrical conductivity occurs when there is metallic bonding, however the electrons in nonmetals are often not metallic. Good electrical and thermal conductivity associated with metallic electrons is seen in carbon (as graphite, along its planes), arsenic, and antimony. Good thermal conductivity occurs in boron, silicon, phosphorus, and germanium; such conductivity is transmitted though vibrations of the crystalline lattices of these elements. Moderate electrical conductivity is observed in the semiconductors boron, silicon, phosphorus, germanium, selenium, tellurium, and iodine.

Many of the nonmetallic elements are hard and brittle, where dislocations cannot readily move so they tend to undergo brittle fracture rather than deforming. Some do deform such as white phosphorus (soft as wax, pliable and can be cut with a knife, at room temperature), in plastic sulfur, and in selenium which can be drawn into wires from its molten state. Graphite is a standard solid lubricant where dislocations move very easily in the basal planes.

Allotropes

Over half of the nonmetallic elements exhibit a range of less stable allotropic forms, each with distinct physical properties. For example, carbon, the most stable form of which is graphite, can manifest as diamond, buckminsterfullerene, amorphous and paracrystalline variations. Allotropes also occur for nitrogen, oxygen, phosphorus, sulfur, selenium and iodine.

Chemical

Nonmetals have relatively high values of electronegativity, and their oxides are usually acidic. Exceptions may occur if a nonmetal is not very electronegative, or if its oxidation state is low, or both. These non-acidic oxides of nonmetals may be amphoteric (like water, H2O) or neutral (like nitrous oxide, N2O), but never basic.

Nonmetals tend to gain electrons during chemical reactions, in contrast to metals which tend to donate electrons. This behavior is related to the stability of electron configurations in the noble gases, which have complete outer shells as summarized by the duet and octet rules of thumb, more correctly explained in terms of valence bond theory.

They typically exhibit higher ionization energies, electron affinities, and standard electrode potentials than metals. Generally, the higher these values are (including electronegativity) the more nonmetallic the element tends to be. For example, the chemically very active nonmetals fluorine, chlorine, bromine, and iodine have an average electronegativity of 3.19—a figure higher than that of any metallic element.

The chemical distinctions between metals and nonmetals is connected to 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 (number of protons in the atomic nucleus) increases. There is a corresponding reduction in atomic radius as the increased nuclear charge draws the outer electrons closer to the nuclear core. In chemical bonding, nonmetals tend to gain electrons due to their higher nuclear charge, resulting in negatively charged ions.

The number of compounds formed by nonmetals is vast. The first 10 places in a "top 20" table of elements most frequently encountered in 895,501,834 compounds, as listed in the Chemical Abstracts Service register for November 2, 2021, were occupied by nonmetals. Hydrogen, carbon, oxygen, and nitrogen collectively appeared in most (80%) of compounds. Silicon, a metalloid, ranked 11th. The highest-rated metal, with an occurrence frequency of 0.14%, was iron, in 12th place. A few examples of nonmetal compounds are: boric acid (), used in ceramic glazes; selenocysteine (), the 21st amino acid of life; phosphorus sesquisulfide (P4S3), found in strike anywhere matches; and teflon ()n), used to create non-stick coatings for pans and other cookware.

Complications

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

First row anomaly

Starting with hydrogen, the first row anomaly primarily arises from the electron configurations of the elements concerned. Hydrogen is notable for its diverse bonding behaviors. It most commonly forms covalent bonds, but it can also lose its single electron in an aqueous solution, leaving behind a bare proton with tremendous polarizing power. Consequently, this proton can attach itself to the lone electron pair of an oxygen atom in a water molecule, laying the foundation for acid-base chemistry. Moreover, a hydrogen atom in a molecule can form a second, albeit weaker, bond with an atom or group of atoms in another molecule. Such bonding, "helps give snowflakes their hexagonal symmetry, binds DNA into a double helix; shapes the three-dimensional forms of proteins; and even raises water's boiling point high enough to make a decent cup of tea."

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

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

Secondary periodicity

An alternation in certain periodic trends, sometimes referred to as secondary periodicity, becomes evident when descending groups 13 to 15, and to a lesser extent, groups 16 and 17. Immediately after the first row of d-block metals, from scandium to zinc, the 3d electrons in the p-block elements—specifically, gallium (a metal), germanium, arsenic, selenium, and bromine—prove less effective at shielding the increasing positive nuclear charge.

The Soviet chemist  gives two more tangible examples:
"The toxicity of some arsenic compounds, and the absence of this property in analogous compounds of phosphorus [P] and antimony [Sb]; and the ability of selenic acid [] to bring metallic gold [Au] into solution, and the absence of this property in sulfuric [] and [] acids."

Higher oxidation states
Roman numerals such as III, V and VIII denote oxidation states

Some nonmetallic elements exhibit oxidation states that deviate from those predicted by the octet rule, which typically results in an oxidation state of –3 in group 15, –2 in group 16, –1 in group 17, and 0 in group 18. Examples include ammonia NH3, hydrogen sulfide H2S, hydrogen fluoride HF, and elemental xenon Xe. Meanwhile, the maximum possible oxidation state increases from +5 in group 15, to +8 in group 18. The +5 oxidation state is observable from period 2 onward, in compounds such as nitric acid HN(V)O3 and phosphorus pentafluoride PCl5. Higher oxidation states in later groups emerge from period 3 onwards, as seen in sulfur hexafluoride SF6, iodine heptafluoride IF7, and xenon(VIII) tetroxide XeO4. For heavier nonmetals, their larger atomic radii and lower electronegativity values enable the formation of compounds with higher oxidation numbers, supporting higher bulk coordination numbers.

Multiple bond formation
Period 2 nonmetals, particularly carbon, nitrogen, and oxygen, show a propensity to form multiple bonds. The compounds formed by these elements often exhibit unique stoichiometries and structures, as seen in the various nitrogen oxides, which are not commonly found in elements from later periods.

Property overlaps 
While certain elements have traditionally been classified as nonmetals and others as metals, some overlapping of properties occurs. Writing early in the twentieth century, by which time the era of modern chemistry had been well-established, Humphrey observed that:
... these two groups, however, are not marked off perfectly sharply from each other; some nonmetals resemble metals in certain of their properties, and some metals approximate in some ways to the non-metals.

Examples of metal-like properties occurring in nonmetallic elements include:
 Silicon has an electronegativity (1.9) comparable with metals such as cobalt (1.88), copper (1.9), nickel (1.91) and silver (1.93);
 The electrical conductivity of graphite exceeds that of some metals;
 Selenium can be drawn into a wire;
 Radon is the most metallic of the noble gases and begins to show some cationic behavior, which is unusual for a nonmetal; and
 In extreme conditions, just over half of nonmetallic elements can form homopolyatomic cations.

Examples of nonmetal-like properties occurring in metals are:
Tungsten displays some nonmetallic properties, sometimes being brittle, having a high electronegativity, and forming only anions in aqueous solution, and predominately acidic oxides.
Gold, the "king of metals" has the highest electrode potential among metals, suggesting a preference for gaining rather than losing electrons. Gold's ionization energy is one of the highest among metals, and its electron affinity and electronegativity are high, with the latter exceeding that of some nonmetals. It forms the Au– auride anion and exhibits a tendency to bond to itself, behaviors which are unexpected for metals. In aurides (MAu, where M = Li–Cs), gold's behavior is similar to that of a halogen. Gold has a large enough nuclear potential that the electrons have to be considered with relativistic effects included which changes some of the properties.

A relatively recent development involves certain compounds of heavier p-block elements, such as silicon, phosphorus, germanium, arsenic and antimony, exhibiting behaviors typically associated with transition metal complexes. This is linked to a small energy gap between their filled and empty molecular orbitals, which are the regions in a molecule where electrons reside and where they can be available for chemical reactions. In such compounds, this allows for unusual reactivity with small molecules like hydrogen (H2), ammonia (NH3), and ethylene (C2H4), a characteristic previously observed primarily in transition metal compounds. These reactions may open new avenues in catalytic applications.

Types 
Nonmetal classification schemes vary widely, with some accommodating as few as two subtypes and others identifying up to seven. For example, the periodic table in the Encyclopaedia Britannica recognizes noble gases, halogens, and other nonmetals, and splits the elements commonly recognized as metalloids between "other metals" and "other nonmetals". On the other hand, seven of twelve color categories on the Royal Society of Chemistry periodic table include nonmetals.

Starting on the right side of the periodic table, three types of nonmetals can be recognized:

 the relatively inert noble gases—helium, neon, argon, krypton, xenon, radon;

 the notably reactive halogen nonmetals—fluorine, chlorine, bromine, iodine; and

 the mixed reactivity "unclassified nonmetals", a set with no widely used collective name—hydrogen, carbon, nitrogen, oxygen, phosphorus, sulfur, selenium. The descriptive phrase unclassified nonmetals is used here for convenience.

The elements in a fourth set are sometimes recognized as nonmetals:

 the generally unreactive  metalloids, sometimes considered a third category distinct from metals and nonmetals—boron, silicon, germanium, arsenic, antimony, tellurium.

The boundaries between these types are not sharp. Carbon, phosphorus, selenium, and iodine border the metalloids and show some metallic character, as does hydrogen.

The greatest discrepancy between authors occurs in metalloid "frontier territory". Some consider metalloids distinct from both metals and nonmetals, while others classify them as nonmetals. Some categorize certain metalloids as metals (e.g., arsenic and antimony due to their similarities to heavy metals). Metalloids resemble the elements universally considered "nonmetals" in having relatively low densities, high electronegativity, and similar chemical behavior.

Noble gases 

Six nonmetals are classified as noble gases: helium, neon, argon, krypton, xenon, and the radioactive radon. In conventional periodic tables they occupy the rightmost column. They are called noble gases due to their exceptionally low chemical reactivity.

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

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

Halogen nonmetals 

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

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

Unclassified nonmetals 

Hydrogen behaves in some respects like a metallic element and in others like a nonmetal. Like a metallic element it can, for example, form a solvated cation in aqueous solution; it can substitute for alkali metals in compounds such as the chlorides (NaCl cf. HCl) and nitrates (KNO3 cf. HNO3), and in certain alkali metal complexes as a nonmetal. It attains this configuration by forming a covalent or ionic bond or, if it has initially given up its electron, by attaching itself to a lone pair of electrons.

Some or all of these nonmetals share several properties. Being generally less reactive than the halogens, most of them can occur naturally in the environment. They have significant roles in biology and geochemistry. Collectively, their physical and chemical characteristics can be described as "moderately non-metallic". Sometimes they have corrosive aspects. Carbon corrosion can occur in fuel cells. Untreated selenium in soils can lead to the formation of corrosive hydrogen selenide gas. Very different, when combined with metals, the unclassified nonmetals can form interstitial or refractory compounds due to their relatively small atomic radii and sufficiently low ionization energies. They also exhibit a tendency to bond to themselves, particularly in solid compounds. Additionally, diagonal periodic table relationships among these nonmetals mirror similar relationships among the metalloids.

Abundance, extraction, and uses

Abundance

The abundance of elements in the universe results from nuclear physics processes like nucleosynthesis and radioactive decay.

The volatile noble gas nonmetal elements are less abundant in the atmosphere than expected based their overall abundance due to cosmic nucleosynthesis. Mechanisms to explain this difference is an important aspect of planetary science. Even within that challenge, the nonmetal element  is unexpectedly depleted. A possible explanation comes from theoretical models of the high pressures in the Earth's core suggest there may be around 1013 tons of xenon, in the form of stable XeFe3 and XeNi3 intermetallic compounds.

Five nonmetals—hydrogen, carbon, nitrogen, oxygen, and silicon—form the bulk of the directly observable structure of the Earth: about 73% of the crust, 93% of the biomass, 96% of the hydrosphere, and over 99% of the atmosphere, as shown in the accompanying table. Silicon and oxygen form highly stable tetrahedral structures, known as silicates. Here, "the powerful bond that unites the oxygen and silicon ions is the cement that holds the Earth's crust together."

In the biomass, the relative abundance of the first four nonmetals (and phosphorus, sulfur, and selenium marginally) is attributed to a combination of relatively small atomic size, and sufficient spare electrons. These two properties enable them to bind to one another and "some other elements, to produce a molecular soup sufficient to build a self-replicating system."

Extraction
Nine of the 23 nonmetallic elements are gases, or form compounds that are gases, and are extracted from natural gas or liquid air. These elements include hydrogen, helium, nitrogen, oxygen, neon, sulfur, argon, krypton, and xenon. For example, nitrogen and oxygen are extracted from air through fractional distillation of liquid air. This method capitalizes on their different boiling points to separate them efficiently. Sulfur was extracted using the Frasch process, which involved injecting superheated water into underground deposits to melt the sulfur, which is then pumped to the surface. This technique leveraged sulfur's low melting point relative to other geological materials. It is now obtained by reacting the hydrogen sulfide in natural gas, with oxygen. Water is formed, leaving the sulfur behind.

 are extracted from the following sources:

 Gases (3): hydrogen, from methane; helium, from natural gas; sulfur, from hydrogen sulfide in natural gas

 Liquids (9): nitrogen, oxygen, neon, argon, krypton and xenon from liquid air; chlorine, bromine and iodine from brine

 Solids (12): boron, from borates; carbon occurs naturally as graphite;  silicon, from silica; phosphorus, from phosphates; iodine, from sodium iodate; radon, as a decay product from uranium ores; fluorine, from fluorite; germanium, arsenic, selenium, antimony and tellurium, from sulfides.

Uses
Uses of nonmetals and non-metallic elements are broadly categorized as domestic, industrial, attenuative (lubricative, retarding, insulating or cooling), and agricultural

Many have domestic and industrial applications in household accoutrements; medicine and pharmaceuticals; and lasers and lighting. They are components of mineral acids; and prevalent in plug-in hybrid vehicles; and smartphones.

A significant number have attenuative and agricultural applications. They are used in lubricants; and flame retardants and fire extinguishers. They can serve as inert air replacements; and are used in cryogenics and refrigerants. Their significance extends to agriculture, through their use in fertilizers.

Additionally, a smaller number of nonmetals or nonmetallic elements find specialized uses in explosives; and welding gases.

Taxonomical history

Background

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

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

The term "nonmetallic" dates back to at least the 16th century. In his 1566 medical treatise, French physician Loys de L'Aunay distinguished substances from plant sources based on whether they originated from metallic or non-metallic soils.

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

Organization of elements by types

Just as the ancients distinguished metals from other minerals, similar distinctions developed as the modern idea of chemical elements emerged in the late 1700s. French chemist Antoine Lavoisier published the first modern list of chemical elements in his revolutionary 1789 Traité élémentaire de chimie. The 33 elements known to Lavoisier were categorized into four distinct groups, including gases, metallic substances, nonmetallic substances that form acids when oxidized, and earths (heat-resistant oxides). Lavoisier's work gained widespread recognition and was republished in twenty-three editions across six languages within its first seventeen years, significantly advancing the understanding of chemistry in Europe and America.

In 1802 the term "metalloids" was introduced for elements with the physical properties of metals but the chemical properties of non-metals. However,
in 1811, the Swedish chemist Berzelius used the term "metalloids" to describe all nonmetallic elements, noting their ability to form negatively charged ions with oxygen in aqueous solutions. 
Thus in 1864, the "Manual of Metalloids" divided all elements into either metals or metalloids, with the latter group including elements now called nonmetals.  Reviews of the book indicated that the term "metalloids" was still endorsed by leading authorities, but there were reservations about its appropriateness. While Berzelius' terminology gained significant acceptance, it later faced criticism from some who found it counterintuitive, misapplied, or even invalid.  The idea of designating elements like arsenic as metalloids had been considered. By as early as 1866, some authors began preferring the term "nonmetal" over "metalloid" to describe nonmetallic elements. In 1875, Kemshead observed that elements were categorized into two groups: non-metals (or metalloids) and metals. He noted that the term "non-metal", despite its compound nature, was more precise and had become universally accepted as the nomenclature of choice.

Development of types

In 1844, , a French doctor, pharmacist, and chemist, established a basic taxonomy of nonmetals to aid in their study. He wrote:

They will be divided into four groups or sections, as in the following:
Organogens—oxygen, nitrogen, hydrogen, carbon
Sulphuroids—sulfur, selenium, phosphorus
Chloroides—fluorine, chlorine, bromine, iodine
Boroids—boron, silicon.

Dupasquier's quartet parallels the modern nonmetal types. The organogens and sulphuroids are akin to the unclassified nonmetals. The chloroides were later called halogens. The boroids eventually evolved into the metalloids, with this classification beginning from as early as 1864. The then unknown noble gases were recognized as a distinct nonmetal group after being discovered in the late 1800s.

His taxonomy was noted for its natural basis. That said, it was a significant departure from other contemporary classifications, since it grouped together oxygen, nitrogen, hydrogen, and carbon.

In 1828 and 1859, the French chemist Dumas classified nonmetals as (1) hydrogen; (2) fluorine to iodine; (3) oxygen to sulfur; (4) nitrogen to arsenic; and (5) carbon, boron and silicon, thereby anticipating the vertical groupings of Mendeleev's 1871 periodic table. Dumas' five classes fall into modern groups 1, 17, 16, 15, and 14 to
13 respectively.

Suggested distinguishing criteria

Much of the early analyses were phenomenological, and a variety of physical, chemical, and atomic properties have been suggested for distinguishing metals from nonmetals (or other bodies); a comprehensive early set of characteristics was stated by Rev Thaddeus Mason Harrisn in the 1803 Minor Encyclopedia .
METAL, in natural history and chemistry, the name of a class of simple bodies; of which it is observed, that they posses; a lustre; that they are opaque; that they arc fusible, or may be melted; that their specific gravity is greater than that of any other bodies yet discovered; that they are better conductors of electricity, than any other body; that they are malleable, or capable of being extended and flattened by the hammer; and that they are ductile or tenacious, that is, capable of being drawn out into threads or wires.

Some criteria did not last long; for instance in 1809, the British chemist and inventor Humphry Davy isolated sodium and potassium, their low densities contrasted with their metallic appearance, so the density property was tenuous although these metals was firmly established by their chemical properties.

Johnson has a similar approach to Mason, distinguishing between metals and nonmetals on the basis of their physical states, electrical conductivity, mechanical properties, and the acid-base nature of their oxides:
 gaseous elements are nonmetals (hydrogen, nitrogen, oxygen, fluorine, chlorine and the noble gases);
 liquids (mercury, bromine) are either metallic or nonmetallic: mercury, as a good conductor, is a metal; bromine, with its poor conductivity, is a nonmetal;
 solids are either ductile and malleable, hard and brittle, or soft and crumbly:
a. ductile and malleable elements are metals;
b. hard and brittle elements include boron, silicon and germanium, which are semiconductors and therefore not metals; and
c. soft and crumbly elements include carbon, phosphorus, sulfur, arsenic, antimony, tellurium and iodine, which have acidic oxides indicative of nonmetallic character.

Several authors have noted that nonmetals generally have low densities and high electronegativity. The accompanying table, using a threshold of 7 g/cm3 for density and 1.9 for electronegativity (revised Pauling), shows that all nonmetals have low density and high electronegativity. In contrast, all metals have either high density or low electronegativity (or both). Goldwhite and Spielman added that, "... lighter elements tend to be more electronegative than heavier ones." The average electronegativity for the elements in the table with densities less than 7 gm/cm3 (metals and nonmetals) is 1.97 compared to 1.66 for the metals having densities of more than 7 gm/cm3.

There is not full agreement about the use of phenomenological properties. Emsley pointed out the complexity of this task, asserting that no single property alone can unequivocally assign elements to either the metal or nonmetal category. Some authors divide elements into metals, metalloids, and nonmetals, but Oderberg disagrees, arguing that by the principles of categorization, anything not classified as a metal should be considered a nonmetal.

Kneen and colleagues proposed that the classification of nonmetals can be achieved by establishing a single criterion for metallicity. They acknowledged that various plausible classifications exist and emphasized that while these classifications may differ to some extent, they would generally agree on the categorization of nonmetals. The describe electrical conductivity as the key property, arguing that this is the most common approach.

One of the most commonly recognized properties used is the temperature coefficient of resistivity, the effect of heating on electrical resistance and conductivity. As temperature rises, the conductivity of metals decreases while that of nonmetals increases. However, plutonium, carbon, arsenic, and antimony appear to defy the norm. When plutonium (a metal) is heated within a temperature range of −175 to +125 °C its conductivity increases. Similarly, despite its common classification as a nonmetallic element, carbon (as graphite) is a semimetal which when heated experiences a decrease in electrical conductivity. Arsenic and antimony, which are occasionally classified as nonmetallic elements are also semimetals, and show behavior similar to carbon.

Comparison of selected properties
The two tables in this section list some of the properties of five types of elements (noble gases, halogen nonmetals, unclassified nonmetals, metalloids and, for comparison, metals) based on their most stable forms at standard temperature and pressure. The dashed lines around the columns for metalloids signify that the treatment of these elements as a distinct type can vary depending on the author, or classification scheme in use.

Physical properties by element type 

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

Chemical properties by element type 

Chemical properties are listed from general characteristics to more specific details.

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

See also
 CHON (carbon, hydrogen, oxygen, nitrogen)
 List of nonmetal monographs
 Metallization pressure
 Nonmetal (astrophysics)
 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
 Addison WE 1964, The Allotropy of the Elements, Oldbourne Press, London
 Atkins PA et al. 2006, Shriver & Atkins' Inorganic Chemistry, 4th ed., Oxford University Press, Oxford, 
 Aylward G and Findlay T 2008, SI Chemical Data, 6th ed., John Wiley & Sons Australia, Milton, 
 Bache AD 1832, "An essay on chemical nomenclature, prefixed to the treatise on chemistry; by J. J. Berzelius", American Journal of Science, vol. 22, pp. 248–277
 Baker et al. PS 1962, Chemistry and You, Lyons and Carnahan, Chicago
 Barton AFM 2021, States of Matter, States of Mind, CRC Press, Boca Raton, 
 Beach FC (ed.) 1911, The Americana: A universal reference library, vol. XIII, Mel–New, Metalloid, Scientific American Compiling Department, New York
 Beard A, Battenberg, C & Sutker BJ 2021, "Flame retardants", in Ullmann's Encyclopedia of Industrial Chemistry, 
 Beiser A 1987, Concepts of modern physics, 4th ed., McGraw-Hill, 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, 
 Benzhen et al. 2020, Metals and non-metals in the periodic table, Philosophical Transactions of the Royal Society A, vol. 378, 20200213
 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 1811, 'Essai sur la nomenclature chimique', Journal de Physique, de Chimie, d'Histoire Naturelle, vol. LXXIII, pp. 253‒286 
 Bhuwalka et al. 2021, "Characterizing the changes in material use due to vehicle electrification", Environmental Science & Technology vol. 55, no. 14, 
 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, 
 Boreskov GK 2003, Heterogeneous Catalysis, Nova Science, New York, 
 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
 Brandt HG & Weiler H, 2000, "Welding and cutting", in Ullmann's Encyclopedia of Industrial Chemistry, 
 Brannt WT 1919, Metal Worker's Handy-book of Receipts and Processes, HC Baird & Company, Philadelphia
 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 (eds.), From atoms to polymers: isoelectronic analogies, VCH, New York, 
 Bynum WF, Browne J & Porter R 1981 (eds), Dictionary of the History of Science, Princeton University Press, Princeton, 
 Cahn RW & Haasen P, Physical Metallurgy: Vol. 1, 4th ed., Elsevier Science, Amsterdam,
 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 Norman NC (ed.), Chemistry of Arsenic, Antimony and Bismuth, Blackie Academic & Professional, London, pp. 1–38, 
 Carrasco et al. 2023, "Antimonene: a tuneable post-graphene material for advanced applications in optoelectronics, catalysis, energy and biomedicine", Chemical Society Reviews, vol. 52, no. 4, p. 1288–1330, 
 Challoner J 2014, The Elements: The New Guide to the Building Blocks of our Universe, Carlton Publishing Group, 
 Chambers E 1743, in "Metal", Cyclopedia: Or an Universal Dictionary of Arts and Sciences (etc.), vol. 2, D Midwinter, London
 Chambers C & Holliday AK 1982, Inorganic Chemistry, Butterworth & Co., London, 
 Chandra X-ray Observatory 2018, Abundance Pie Chart, accessed 26 October 2023
 Chapin FS, Matson PA & Vitousek PM 2011, Earth's climate system, in Principles of Terrestrial Ecosystem Ecology, Springer, New York, 
 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, 
 Chedd G 1969, Half-way elements: The technology of metalloids, Double Day, Garden City, NY
 Chemical Abstracts Service 2021, CAS REGISTRY database as of November 2, Case #01271182
 Chen K 1990, Industrial Power Distribution and Illuminating Systems, Marcel Dekker, New York, 
 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 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
 Cressey D 2010, "Chemists re-define hydrogen bond" , Nature newsblog, accessed August 23, 2017
 Crichton R 2012, Biological Inorganic Chemistry: A New Introduction to Molecular Structure and Function, 2nd ed., Elsevier, Amsterdam, 
 Criswell B 2007, "Mistake of having students be Mendeleev for just a day", Journal of Chemical Education, vol. 84, no. 7, pp. 1140–1144, 
 Crow JM 2013, Main group renaissance, Chemistry World, 31 May, accessed 26 December 2023
 Csele M 2016, Lasers, in Ullmann's Encyclopedia of Industrial Chemistry, 
 Dalton L 2019, "Argon reacts with nickel under pressure-cooker conditions", Chemical & Engineering News, accessed November 6, 2019
 de Clave E 1651, Nouvelle Lumière philosophique des vrais principes et élémens de nature, et qualité d'iceux, contre l'opinion commune, Olivier de Varennes, Paris
 Daniel PL & Rapp RA 1976, "Halogen corrosion of metals", in Fontana MG & Staehle RW (eds.), Advances in Corrosion Science and Technology, Springer, Boston, 
 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
 Davis et al. 2006, "Atomic iodine lasers", in Endo M & Walter RF (eds) 2006, Gas Lasers, CRC Press, Boca Raton, Florida, 
 DeKock RL & Gray HB 1989, Chemical structure and bonding, University Science Books, Mill Valley, CA, 
 Dejonghe L 1998, "Zinc–lead deposits of Belgium", Ore Geology Reviews, vol. 12, no. 5, 329–354, 
 Desai PD, James HM & Ho CY 1984, "Electrical resistivity of aluminum and manganese", Journal of Physical and Chemical Reference Data, vol. 13, no. 4, 
 Donohue J 1982, The Structures of the Elements, Robert E. Krieger, Malabar, Florida, 
 Dorsey MG 2023, Holding Their Breath: How the Allies Confronted the Threat of Chemical Warfare in World War II, Cornell University Press, Ithaca, New York, pp. 12–13, 
 Douglade J, Mercier R 1982, Structure cristalline et covalence des liaisons dans le sulfate d’arsenic(III), As2(SO4)3, Acta Crystallographica Section B, vol. 38, no, 3, 720–723, 
  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, 
 Duffus JH 2002, " 'Heavy metals'—A meaningless term?", Pure and Applied Chemistry, vol. 74, no. 5, pp. 793–807, 
 Dumas JBA 1828, Traité de Chimie Appliquée aux Arts, Béchet Jeune, Paris
 Dumas JBA 1859, Mémoire sur les Équivalents des Corps Simples, Mallet-Bachelier, Paris
 Dupasquier A 1844, Traité élémentaire de chimie industrielle, Charles Savy Juene, Lyon
 Eagleson M 1994, Concise Encyclopedia Chemistry, Walter de Gruyter, Berlin, 
 Earl B & Wilford D 2021, Cambridge O Level Chemistry, Hodder Education, London, 
 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, , 
 Elliot A 1929, "The absorption band spectrum of chlorine", Proceedings of the Royal Society A, vol. 123, no. 792, pp. 629–644, 
 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, 
 Encyclopaedia Britannica, 2021, Periodic table, accessed September 21, 2021
 Engesser TA & Krossing I 2013, "Recent advances in the syntheses of homopolyatomic cations of the non metallic elements , , , , , ,  and ", Coordination Chemistry Reviews, vol. 257, nos. 5–6, pp. 946–955, 
 Erman P & Simon P 1808, "Third report of Prof. Erman and State Architect Simon on their joint experiments", Annalen der Physik, vol. 28, no. 3, pp. 347–367
 Evans RC 1966, An Introduction to Crystal Chemistry, 2nd ed., Cambridge University, Cambridge
 Faraday M 1853, The Subject Matter of a Course of Six Lectures on the Non-metallic Elements, (arranged by John Scoffern), Longman, Brown, Green, and Longmans, London
 Field JE (ed.) 1979, The Properties of Diamond, Academic Press, 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, 
 Fox M 2010, Optical Properties of Solids, 2nd ed., Oxford University Press, 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, 
 Ganguly A 2012, Fundamentals of Inorganic Chemistry, 2nd ed., Dorling Kindersley (India), New Delhi 
 Gargaud M et al. (eds.) 2006, Lectures in Astrobiology, vol. 1, part 1: The Early Earth and Other Cosmic Habitats for Life, Springer, Berlin, 
 Gatti M, Tokatly IV & Rubio A, 2010, Sodium: a charge-transfer insulator at high pressures, Physical Review Letters, vol. 104, no. 21, 
 Georgievskii VI 1982, Mineral compositions of bodies and tissues of animals, in Georgievskii VI, Annenkov BN & Samokhin VT (eds), Mineral Nutrition of Animals: Studies in the Agricultural and Food Sciences, Butterworths, London, 
 Gillespie RJ, Robinson EA 1959, The sulfuric acid solvent system, in Emeléus HJ, Sharpe AG (eds), Advances in Inorganic Chemistry and Radiochemistry, vol. 1, pp. 386–424, Academic Press, New York
 Gillham EJ 1956, A semi-conducting antimony bolometer, Journal of Scientific Instruments, vol. 33, no. 9, 
 Glinka N 1960, 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, 
 Goldsmith RH 1982, "Metalloids", Journal of Chemical Education, vol. 59, no. 6, pp. 526–527, 
 Goldwhite H & Spielman JR 1984, College Chemistry, Harcourt Brace Jovanovich, San Diego, 
 Goodrich BG 1844, A Glance at the Physical Sciences, Bradbury, Soden & Co., Boston
 Gresham et al. 2015, Lubrication and lubricants, in Kirk-Othmer Encyclopedia of Chemical Technology, John Wiley & Sons, , accessed Jun 3, 2024
 Grondzik WT et al. 2010, Mechanical and Electrical Equipment for Buildings, 11th ed., John Wiley & Sons, Hoboken, 
 Government of Canada 2015, Periodic table of the elements, accessed August 30, 2015
 Graves Jr JL 2022, A Voice in the Wilderness: A Pioneering Biologist Explains How Evolution Can Help Us Solve Our Biggest Problems, Basic Books, New York, ,
 Green D 2012, The Elements, Scholastic, Southam, Warwickshire, 
 Greenberg A 2007, From alchemy to chemistry in picture and story, John Wiley & Sons, Hoboken, NJ, 978-0-471-75154-0
 Greenwood NN 2001, Main group element chemistry at the millennium, Journal of the Chemical Society, Dalton Transactions, no. 14, pp. 2055–66, 
 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, 
 Hall RA 2021, Pop Goes the Decade: The 2000s, ABC-CLIO, Santa Barbara, California, 
 Haller EE 2006, "Germanium: From its discovery to SiGe devices", Materials Science in Semiconductor Processing, vol. 9, nos 4–5, accessed 9 October 2013
 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 behaviors, 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, 
 Harbison RD, Bourgeois MM & Johnson GT 2015, Hamilton and Hardy's Industrial Toxicology, 6th ed., John Wiley & Sons, Hoboken, 
 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
 Harris TM 1803, The Minor Encyclopedia, vol. III, West & Greenleaf, Boston
 Hein M & Arena S 2011, Foundations of College Chemistry, 13th ed., John Wiley & Sons, Hoboken, New Jersey, 
 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 & Hulme PG 2017, Chemistry in Context, 7th ed., Oxford University Press, Oxford, 
 Hoefer F 1845, Nomenclature et Classifications Chimiques, J.-B. Baillière, Paris
 Holderness A & Berry M 1979, Advanced Level Inorganic Chemistry, 3rd ed., Heinemann Educational Books, London, 
 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, 
 House JE 2013, Inorganic Chemistry, 2nd ed., Elsevier, Kidlington, 
 Huang Y 2018, Thermodynamics of materials corrosion, in Huang Y & Zhang J (eds), Materials Corrosion and Protection, De Gruyter, Boston, pp. 25–58, 
 Humphrey TPJ 1908, "Systematic course of study, Chemistry and physics", Pharmaceutical Journal, vol. 80, p. 58
 Hussain et al. 2023, "Tuning the electronic properties of molybdenum di-sulphide monolayers via doping using first-principles calculations", Physica Scripta, vol. 98, no. 2, 
 Imberti C & Sadler PJ, 2020, "150 years of the periodic table: New medicines and diagnostic agents", in Sadler PJ & van Eldik R 2020, Advances in Inorganic Chemistry, vol. 75, Academic Press, 
 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,  
 Jensen WB 1986, Classification, symmetry and the periodic table, Computers & Mathematics with Applications, vol. 12B, nos. 1/2, pp. 487−510, 
 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, 
 Jordan JM 2016 " 'Ancient episteme' and the nature of fossils: a correction of a modern scholarly error", History and Philosophy of the Life Sciences, vol. 38, no, 1, pp. 90–116, 
 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, 
 Kemshead WB 1875, Inorganic chemistry, William Collins, Sons, & Company, London
 Kernion MC & Mascetta JA 2019, Chemistry: The Easy Way, 6th ed., Kaplan, New York, 
 King AH 2019, "Our elemental footprint", Nature Materials, vol. 18, 
 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, 
 Kiiski et al. 2016, "Fertilizers, 1. General", in Ullmann's Encyclopedia of Industrial Chemistry, 
 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, 
 Koenig SH 1962, in Proceedings of the International Conference on the Physics of Semiconductors, held at Exeter, July 16–20, 1962, The Institute of Physics and the Physical Society, London
 Kosanke et al. 2012, Encyclopedic Dictionary of Pyrotechnics (and Related Subjects), Part 3 – P to Z, Pyrotechnic Reference Series No. 5, Journal of Pyrotechnics, Whitewater, Colorado, 
 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
 Larrañaga MD, Lewis RJ & Lewis RA 2016, Hawley's Condensed Chemical Dictionary, 16th ed., Wiley, Hoboken, New York, 
 Lavoisier A 1790, Elements of Chemistry, R Kerr (trans.), William Creech, Edinburgh
 Lee JD 1996, Concise Inorganic Chemistry, 5th ed., Blackwell Science, Oxford, 
 Lémery N 1699, Traité universel des drogues simples, mises en ordre alphabetique, L d'Houry, Paris, p. 118
 Lewis RJ 1993, Hawley's Condensed Chemical Dictionary, 12th ed., Van Nostrand Reinhold, New York, 
 Lewis RS & Deen WM 1994, "Kinetics of the reaction of nitric oxide with oxygen in aqueous solutions", Chemical Research in Toxicology, vol. 7, no. 4, pp. 568–574, 
 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
 Lundgren A & Bensaude-Vincent B 2000, Communicating chemistry: textbooks and their audiences, 1789–1939, Science History, Canton, MA, 
 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, 
 Malone LJ & Dolter T 2008, Basic Concepts of Chemistry, 8th ed., John Wiley & Sons, Hoboken, 
 Mann et al. 2000, Configuration energies of the d-block elements, Journal of the American Chemical Society, vol. 122, no. 21, pp. 5132–5137, 
 Maosheng M 2020, "Noble gases in solid compounds show a rich display of chemistry with enough pressure", Frontiers in Chemistry, vol. 8, 
 Maroni M, Seifert B & Lindvall T (eds) 1995, "Physical pollutants", in Indoor Air Quality: A Comprehensive Reference Book, Elsevier, Amsterdam, 
 Martin JW 1969, Elementary Science of Metals, Wykeham Publications, London
 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, , , 
 McMillan P 2006, "A glass of carbon dioxide", Nature, vol. 441, 
 Mendeléeff DI 1897, The Principles of Chemistry, vol. 2, 5th ed., trans. G Kamensky, AJ Greenaway (ed.), Longmans, Green & Co., London
 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 1958, Qualitative Analysis: An Introduction to Equilibrium and Solution Chemistry, McGraw-Hill, New York
 Moeller T et al. 1989, Chemistry: With Inorganic Qualitative Analysis, 3rd ed., Academic Press, New York, 
 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, 
 Morely HF & Muir MM 1892, Watt's Dictionary of Chemistry, vol. 3, Longman's Green, and Co., London
 Moss, TS 1952, Photoconductivity in the Elements, Butterworths Scientific, London
 Myers RT 1979, "Physical and chemical properties and bonding of metallic elements", Journal of Chemical Education, vol. 56, no. 11, pp. 712–73, 
 Obodovskiy I 2015, Fundamentals of Radiation and Chemical Safety, Elsevier, Amsterdam, 
 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 , 
 Oxford English Dictionary 1989, "nonmetal"
 Orisakwe OE 2012, Other heavy metals: antimony, cadmium, chromium and mercury, in Pacheco-Torgal F, Jalali S & Fucic A (eds), Toxicity of Building Materials, Woodhead Publishing, Oxford, pp. 297–333, 
 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
 Partington JR 1964, A history of chemistry, vol. 4, Macmillan, London
 Pascoe KJ 1982, An Introduction to the Properties of Engineering Materials, 3rd ed., Von Nostrand Reinhold (UK), Wokingham, Berkshire, 
 Pauling L 1947, General chemistry: An introduction to descriptive chemistry and modern chemical theory, WH Freeman, San Francisco
 Pawlicki T, Scanderbeg DJ & Starkschall G 2016, Hendee's Radiation Therapy Physics, 4th ed., John Wiley & Sons, Hoboken, NJ, p. 228, 
 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
 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, 
 Power PP 2010, Main-group elements as transition metals, Nature, vol. 463, 14 January 2010, pp. 171–177, 
 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, 
 Ramdohr P 1969, The Ore Minerals and Their Intergrowths, Pergamon Press, Oxford
 Rao CNR & Ganguly PA 1986, "New criterion for the metallicity of elements", Solid State Communications, vol. 57, no. 1, pp. 5–6, 
 Rao KY 2002, Structural chemistry of glasses, Elsevier, Oxford, 
 Rayner-Canham G 2018, "Organizing the transition metals", in Scerri E & Restrepo G (Ed's.) Mendeleev to Oganesson: A multidisciplinary perspective on the periodic table, Oxford University, New York, 
 Rayner-Canham G 2020, The Periodic Table: Past, Present and Future, World Scientific, New Jersey, 
 Redmer R, Hensel F & Holst B (eds) 2010, "Metal-to-Nonmetal Transitions", Springer, Berlin, 
 Regnault MV 1853, Elements of Chemistry, vol. 1, 2nd ed., Clark & Hesser, Philadelphia
 Reilly C 2002, Metal Contamination of Food, Blackwell Science, Oxford, 
 Reinhardt et al. 2015, Inerting in the chemical industry, Linde, Pullach, Germany, accessed October 19, 2021
 Remy H 1956, Treatise on Inorganic Chemistry, Anderson JS (trans.), Kleinberg J (ed.), vol. II, Elsevier, Amsterdam
 Renouf E 1901, "Lehrbuch der Anorganischen Chemie", Science, vol. 13, no. 320, 
 Restrepo G, Llanos EJ & Mesa H 2006, "Topological space of the chemical elements and its properties", Journal of Mathematical Chemistry, vol. 39, 
 Rieck GD 1967, Tungsten and its Compounds,  Pergamon Press, Oxford
 Ritter SK 2011, "The case of the missing xenon", Chemical & Engineering News, vol. 89, no. 9, 
 Rochow EG 1966, The Metalloids, DC Heath and Company, Boston
 Rosenberg E 2013, Germanium-containing compounds, current knowledge and applications, in Kretsinger RH, Uversky VN & Permyakov EA (eds), Encyclopedia of Metalloproteins, Springer, New York, 
 Roscoe HE & Schorlemmer FRS 1894, A Treatise on Chemistry: Volume II: The Metals, D Appleton, New York
 Royal Society of Chemistry 2021, Periodic Table: Non-metal, accessed September 3, 2021
 Rudakiya DM & Patel Y 2021, Bioremediation of metals, metalloids, and nonmetals, in Panpatte DG & Jhala YK (eds), Microbial Rejuvenation of Polluted Environment, vol. 2, Springer Nature, Singapore, pp. 33–49, 
 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 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, 
 Scerri E 2020, The Periodic Table: Its Story and Its Significance, Oxford University Press, New York, 
 Schaefer JC 1968, "Boron" in Hampel CA (ed.), The Encyclopedia of the Chemical Elements, Reinhold, New York
 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, 
 Schweitzer GK & Pesterfield LL 2010, Aqueous Chemistry of the Elements, Oxford University Press, Oxford, 
 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
 Scott WAH 2001, Chemistry Basic Facts, 5th ed., HarperCollins, Glasgow, 
 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, 
 Shchukarev SA 1977, New views of D. I. Mendeleev's system. I. Periodicity of the stratigraphy of atomic electronic shells in the system, and the concept of Kainosymmetry", Zhurnal Obshchei Kimii, vol. 47, no. 2, pp. 246–259
 Shkol’nikov EV 2010, "Thermodynamic characterization of the amphoterism of oxides M2O3 (M = , , ) 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, 
 Slye OM Jr 2008, "Fire extinguishing agents", in Ullmann's Encyclopedia of Industrial Chemistry, 
 Smith A 1906, Introduction to Inorganic Chemistry, The Century Co., New York
 Smith A & Dwyer C 1991, Key Chemistry: Investigating Chemistry in the Contemporary World: Book 1: Materials and Everyday Life, Melbourne University Press, Carlton, Victoria, 
 Smith DW 1990, Inorganic Substances: A Prelude to the Study of Descriptive Chemistry, Cambridge University Press, Cambridge, 
 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, 
 Smulders E & Sung E 2011, "Laundry Detergents, 2, Ingredients and Products", In Ullmann's Encyclopedia of Industrial Chemistry, 
 Spencer JN, Bodner GM, Rickard LY 2012, Chemistry: Structure & Dynamics, 5th ed., John Wiley & Sons, Hoboken, 
 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 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, 
 Stillman JM 1924, The Story of Early Chemistry, D. Appleton, New York
 Stott RWA 1956, Companion to Physical and Inorganic Chemistry, Longmans, Green and Co, London
 Stuke J 1974, "Optical and electrical properties of selenium", in Zingaro RA & Cooper WC (eds.), Selenium, Van Nostrand Reinhold, New York, pp. 174
 Strathern P 2000, Mendeleyev's dream: The Quest for the Elements, Hamish Hamilton, London, 
 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
 Tidy CM 1887, Handbook of Modern Chemistry, 2nd ed., Smith, Elder & Co., London
 Timberlake KC 1996, Chemistry: An Introduction to General, Organic, and Biological Chemistry, 6th ed., HarperCollinsCollege, 
 Toon R 2011, "The discovery of fluorine", Education in Chemistry, Royal Society of Chemistry, accessed 7 October 2023
 Tregarthen L 2003, Preliminary Chemistry, Macmillan Education: Melbourne, 
 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, pp. 1703‒1707, 
 Vernon R 2020, "Organising the metals and nonmetals", Foundations of Chemistry, vol. 22, pp. 217‒233 (open access)
 Vij et al. 2001, Polynitrogen chemistry. Synthesis, characterization, and crystal structure of surprisingly stable fluoroantimonate salts of N5+. Journal of the American Chemical Society, vol. 123, no. 26, pp. 6308−6313,  
 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
 Wang HS, Lineweaver CH & Ireland TR 2018, The elemental abundances (with uncertainties) of the most Earth-like planet, Icarus, vol. 299, pp. 460–474, 
 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 & Leicester HM 1968, Discovery of the Elements, 7th ed., Journal of Chemical Education, Easton, Pennsylvania
 Weetman C & Inoue S 2018, The road travelled: After main-group elements as transition metals, ChemCatChem, vol. 10, no. 19, pp. 4213–4228, 
 Welcher SH 2009, High marks: Regents Chemistry Made Easy, 2nd ed., High Marks Made Easy, New York,  
 Weller et al. 2018, Inorganic Chemistry, 7th ed., Oxford University Press, Oxford, 
 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
 Whiteford GH & and Coffin RG 1939, Essentials of College Chemistry, 2nd ed., Mosby Co., St Louis
 Whitten KW & Davis RE 1996, General Chemistry, 5th ed., Saunders College Publishing, Philadelphia, 
 Wibaut P 1951, Organic Chemistry, Elsevier Publishing Company, New York
 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, 
 Windmeier C & Barron RF 2013, "Cryogenic technology", in Ullmann's Encyclopedia of Industrial Chemistry, 
 Winstel G 2000, "Electroluminescent materials and devices", in Ullmann's Encyclopedia of Industrial Chemistry, 
 Wismer RK 1997, Student Study Guide, General Chemistry: Principles and Modern Applications, 7th ed.,  Prentice Hall, Upper Saddle River, 
 Woodward et al. 1999, "The electronic structure of metal oxides", In Fierro JLG (ed.), Metal Oxides: Chemistry and Applications, CRC Press, Boca Raton, 
 World Economic Forum 2021, Visualizing the abundance of elements in the Earth's crust, accessed 21 March 2024
 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,  
 Yin et al. 2018, Hydrogen-assisted post-growth substitution of tellurium into molybdenum disulfide monolayers with tunable compositions, Nanotechnology, vol. 29, no 14,  
 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, 
 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, 
 Zhigal'skii GP & Jones BK 2003, The Physical Properties of Thin Metal Films, Taylor & Francis, London, 
 Zhu W 2020, Chemical Elements In Life, World Scientific, Singapore, 
 Zhu et al. 2014, "Reactions of xenon with iron and nickel are predicted in the Earth's inner core", Nature Chemistry, vol. 6, , 
 Zhu et al. 2022, Introduction: basic concept of boron and its physical and chemical properties, in Fundamentals and Applications of Boron Chemistry, vol. 2, Zhu Y (ed.), Elsevier, Amsterdam, 
 Zumdahl SS & DeCoste DJ 2010, Introductory Chemistry: A Foundation, 7th ed., Cengage Learning, Mason, Ohio,

External links
 

Nonmetals
Periodic table