Nonmetal

A periodic table extract Template:Nowrap

alt=A grid with 7 rows labeled periods "1" to "7" and 10 columns labeled as groups "1", "2", "3–11", and "12" to "18". ¶ Most cells represent one chemical element and are labeled with its 1 or 2 letter symbol in a large font above its name. Cells in column 3 (labeled "3–11") represent a series of elements and are labeled with the first and last element's symbol. ¶ Row 1 has cells in the first and last columns, with an empty gap between. Rows 2–3 have 8 cells, with a gap between the first 2 and last 6 columns. Rows 4–7 have cells in all 10 columns. ¶ A bold falling staircase line separates the rightmost 6/5/4/3/2/1 cells in rows 2–7. ¶ 17 cells above and right of the staircase are tan-colored: both cells row 1 and all cells to its right except the first one. ¶ 9 cells along the staircase are specially colored: gray in rows 2–5 and brown in rows 6-7: the first cell after it in rows 2–7 and first cell before in rows 4/5/7. ¶ The rest of the cells have light gray letters on a white background.

Template:Legend inlinealways/usually considered nonmetals<ref name="Larrañaga"/><ref name="Steudel"/><ref name="Vernon2013"/>

Template:Legend inlinemetalloids, sometimes considered nonmetals

Template:Legend inlinestatus as nonmetal or metal unconfirmed<ref>At: Restrepo et al. 2006, p. 411; Thornton & Burdette 2010, p. 86; Hermann, Hoffmann & Ashcroft 2013, pp. 11604‒1‒11604‒5; Ts: Template:Cn Og: Smits et al. 2020</ref>

Template:Sidebar periodic table 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 account for about 98% of the mass of the observable universe. Five nonmetallic elements—hydrogen, carbon, nitrogen, oxygen, and silicon—form the bulk of Earth’s atmosphere, biosphere, crust and oceans, although metallic elements are believed to be slightly more than half of the overall composition of the Earth.

Chemical compounds and alloys involving multiple elements including nonmetals are widespread. Industrial uses of nonmetals as the dominant component include in electronics, combustion, lubrication and machining.

Most nonmetallic elements were identified in the 18th and 19th centuries. While a distinction between metals and other minerals had existed since antiquity, a 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. In contemporary research usage it is common to use a distinction between metal and not-a-metal based upon the electronic structure of the solids; the elements carbon, arsenic and antimony are then semimetals, a subclass of metals. The rest of the nonmetallic elements are insulators, some of which such as silicon and germanium can readily accommodate dopants that change the electrical conductivity leading to semiconducting behavior.

Definition and applicable elements

Unless otherwise noted, this article describes the stable form of an element at standard temperature and pressure (STP).Template:Efn

File:Arsen 1a.jpg

While arsenic (here sealed in a container to prevent tarnishing) has a shiny appearance and is a reasonable conductor of heat and electricity, it is soft and brittle and its chemistry is predominately nonmetallic.<ref>Pascoe 1982, p. 3Template:Broken anchor</ref>

Nonmetallic chemical elements are often broadly defined as those that mostly lack properties commonly associated with metals—namely shininess, pliability, good thermal and electrical conductivity (due to their band structure), and a general capacity to form basic oxides.<ref>Malone & Dolter 2010, pp. 110–111</ref><ref name="Porterfield"/> There is no widely accepted precise definition in terms of these properties;<ref>Godovikov & Nenasheva 2020, p. 4; Morely & Muir 1892, p. 241</ref> any list of nonmetals is open to debate and revision.<ref name="Larrañaga">Larrañaga, Lewis & Lewis 2016, p. 988</ref>

Fourteen elements are almost always recognized as nonmetals:<ref name="Larrañaga"/><ref name="Steudel">Steudel 2020, p. 43: Steudel's monograph is an updated translation of the fifth German edition of 2013, incorporating the literature up to Spring 2019.</ref> Template:Hlist Template:Hlist Template:Hlist

Three more are commonly classed as nonmetals, but some sources list them as "metalloids",<ref name="Vernon2013">Vernon 2013</ref> a term which refers to elements intermediate between metals and nonmetals:<ref name="Vernon2020p220">Vernon 2020, p. 220; Rochow 1966, p. 4</ref> Template:Hlist

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

About 15–20% of the 118 known elements<ref>IUPAC Periodic Table of the Elements</ref> are thus classified as nonmetals.Template:Efn

General properties

Physical

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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.<ref>Wibaut 1951, p. 33: "Many substances ...are colourless and therefore show no selective absorption in the visible part of the spectrum."</ref> 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".<ref>Elliot 1929, p. 629</ref>Template:Efn The shininess of boron, graphite (carbon), silicon, black phosphorus, germanium, arsenic, selenium, antimony, tellurium, and iodineTemplate:Efn is a result of the electrons reflecting incoming visible light.<ref>Wiberg 2001, p. 416; Wiberg is here referring to iodine.</ref>

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.<ref name="Kneen">Kneen, Rogers & Simpson 1972, pp. 261–264</ref> The solid nonmetals have low densities and low mechanical strength (being either hard and brittle, or soft and crumbly),<ref name="ReferenceA">Johnson 1966, p. 4</ref> and a wide range of electrical conductivity.Template:Efn

This diversity stems from variability in crystallographic 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.<ref>Zumdahl & DeCoste 2010, pp. 455, 456, 469, A40; Earl & Wilford 2021, p. 3-24</ref> In contrast, nonmetals that form extended structures, such as long chains of selenium atoms,<ref>Template:Cite journal</ref> sheets of carbon atoms in graphite,<ref>Wiberg 2001, pp. 780</ref> or three-dimensional lattices of silicon atoms<ref>Wiberg 2001, pp. 824, 785</ref> have higher melting and boiling points, and are all solids. 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,<ref>Siekierski & Burgess 2002, p. 86</ref> carbon,<ref>Charlier, Gonze & Michenaud 1994</ref> phosphorus,<ref>Taniguchi et al. 1984, p. 867: "... black phosphorus ... [is] characterized by the wide valence bands with rather delocalized nature."; Carmalt & Norman 1998, p. 7: "Phosphorus ... should therefore be expected to have some metalloid properties."; Du et al. 2010: Interlayer interactions in black phosphorus, which are attributed to van der Waals-Keesom forces, are thought to contribute to the smaller band gap of the bulk material (calculated 0.19 eV; observed 0.3 eV) as opposed to the larger band gap of a single layer (calculated ~0.75 eV).</ref> arsenic,<ref>Wiberg 2001, pp. 742</ref> selenium,<ref>Evans 1966, pp. 124–25</ref> antimony,<ref>Wiberg 2001, pp. 758</ref> tellurium<ref>Stuke 1974, p. 178; Donohue 1982, pp. 386–87; Cotton et al. 1999, p. 501</ref> and iodine.<ref>Steudel 2020, p. 601: "... Considerable orbital overlap can be expected. Apparently, intermolecular multicenter bonds exist in crystalline iodine that extend throughout the layer and lead to the delocalization of electrons akin to that in metals. This explains certain physical properties of iodine: the dark color, the luster and a weak electric conductivity, which is 3400 times stronger within the layers then perpendicular to them. Crystalline iodine is thus a two-dimensional semiconductor."; Segal 1989, p. 481: "Iodine exhibits some metallic properties ..."</ref>

Some general physical differences
between elemental metals and nonmetals<ref name="Kneen"/>

Aspect	Metals	Nonmetals
Appearance and form	Shiny if freshly prepared or fractured; few colored;<ref>Taylor 1960, p. 207; Brannt 1919, p. 34</ref> all but one solid<ref name="Green">Green 2012, p. 14</ref>	Shiny, colored or transparent;<ref>Spencer, Bodner & Rickard 2012, p. 178</ref> all but one solid or gaseous<ref name="Green"/>
Density	Often higher	Often lower
Plasticity	Mostly malleable and ductile	Often brittle solids
Electrical conductivity<ref>Redmer, Hensel & Holst 2010, preface</ref>	Good	Poor to good
Electronic structure<ref name="K&W"/>	Metal or semimetalic	Semimetal, semiconductor, or insulator

Covalently bonded nonmetals often share only the electrons required to achieve a noble gas electron configuration.<ref>DeKock & Gray 1989, pp. 423, 426—427</ref> 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. In contrast antimony has buckled layers in which each antimony atom is singly bonded with three other nearby atoms.<ref>Boreskov 2003, p. 45</ref>

Good electrical conductivity occurs when there is metallic bonding,<ref name="Ashcroft and Mermin">Ashcroft and Mermin</ref> however the electrons in some nonmetals are not metallic.<ref name="Ashcroft and Mermin"/> Good electrical and thermal conductivity associated with metallic electrons is seen in carbon (as graphite, along its planes), arsenic, and antimony.Template:Efn Good thermal conductivity occurs in boron, silicon, phosphorus, and germanium;<ref name="A&W"/> such conductivity is transmitted though vibrations of the crystalline lattices (phonons of these elements.<ref>Yang 2004, p. 9</ref> Moderate electrical conductivity is observed in the semiconductors<ref>Wiberg 2001, pp. 416, 574, 681, 824, 895, 930; Siekierski & Burgess 2002, p. 129</ref> boron, silicon, phosphorus, germanium, selenium, tellurium, and iodine.

Many of the nonmetallic elements are hard and brittle,<ref name="ReferenceA"/> where dislocations cannot readily move so they tend to undergo brittle fracture rather than deforming.<ref>Template:Cite book</ref> Some do deform such as white phosphorus (soft as wax, pliable and can be cut with a knife at room temperature),<ref name="Holderness 1979, p. 255">Faraday 1853, p. 42; Holderness & Berry 1979, p. 255</ref> plastic sulfur,<ref name="ReferenceE">Partington 1944, p. 405</ref> and selenium which can be drawn into wires from its molten state.<ref name="ReferenceF">Regnault 1853, p. 208</ref> Graphite is a standard solid lubricant where dislocations move very easily in the basal planes.<ref name=":1">Template:Cite journal</ref>

Allotropes

Template:Multiple image Template:Main list Over half of the nonmetallic elements exhibit a range of less stable allotropic forms, each with distinct physical properties.<ref>Barton 2021, p. 200</ref> For example, carbon, the most stable form of which is graphite, can manifest as diamond, buckminsterfullerene,<ref>Wiberg 2001, p. 796</ref> amorphous<ref>Shang et al. 2021</ref> and paracrystalline<ref>Tang et al. 2021</ref> variations. Allotropes also occur for nitrogen, oxygen, phosphorus, sulfur, selenium and iodine.<ref>Steudel 2020, passim; Carrasco et al. 2023; Shanabrook, Lannin & Hisatsune 1981, pp. 130–133</ref>

Chemical

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Some general chemistry-based
differences between metals and nonmetals<ref name="Kneen"/>

Aspect		Metals	Nonmetals
Reactivity<ref>Weller et al. 2018, preface</ref>		Wide range: very reactive to noble
Oxides	lower	Basic	Acidic; never basic<ref name="ReferenceC">Abbott 1966, p. 18</ref>
	higher	Increasingly acidic
Compounds with metals<ref>Ganguly 2012, p. 1-1</ref>		Alloys	Covalent or Ionic
Ionization energy<ref name="AylwardIE"/>		Low to high	Moderate to very high
Electronegativity<ref name="AylwardEN"/>		Low to high	Moderate to very high

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<ref>Eagleson 1994, 1169</ref>) or neutral (like nitrous oxide, N₂O<ref>Moody 1991, p. 365</ref>Template:Efn), but never basic.

They tend to gain electrons during chemical reactions, in contrast to metallic elements which tend to donate electrons. This behavior is related to the stability of electron configurations in the noble gases, which have complete outer shells, empirically described by the duet and octet rules of thumb, more correctly explained in terms of valence bond theory.<ref>Smith 1990, pp. 177–189</ref>

The chemical differences between metals and nonmetals stem from variations in how strongly atoms attract and retain electrons. Across a period of the periodic table, the nuclear charge increases as more protons are added to the nucleus.<ref>Young et al. 2018, p. 753</ref> However, because the number of inner electron shells remains constant, the effective nuclear charge experienced by the outermost electrons also increases, pulling them closer to the nucleus. This leads to a corresponding reduction in atomic radius,<ref>Brown et al. 2014, p. 227</ref> and a greater tendency of these elements to gain electrons during chemical reactions, forming negatively charged ions.<ref>Moore 2016; Burford, Passmore & Sanders 1989, p. 54</ref> Nonmetals, which occupy the right-hand side of the periodic table, exemplify this behavior.

Nonmetals typically exhibit higher ionization energies, electron affinities, and standard electrode potentials than metals. The higher these values are (including electronegativity) the more nonmetallic the element tends to be.<ref>Yoder, Suydam & Snavely 1975, p. 58</ref> For example, the chemically very active nonmetals fluorine, chlorine, bromine, and iodine have an average electronegativity of 3.19—a figureTemplate:Efn higher than that of any metallic element.

The number of compounds formed by nonmetals is vast.<ref>Brady & Senese 2009, p. 69</ref> 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.<ref>Chemical Abstracts Service 2021</ref>

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

File:1x1.png

Condensed periodic table highlighting the first row of each block: Template:Color box Template:Color box Template:Color box and Template:Color box

Period

Template:Nowrap

1

style="border:solid black;border-width:2px 1px 2px 2px;background-color:Template:Element color;" | H 1

style="border:solid black;border-width:2px 2px 2px 1px;background-color:Template:Element color;" | He 2

p-block

2

Li 3

Be 4

style="border:solid black;border-width:2px 1px 2px 2px;background-color:Template:Element color;" | B 5

style="border:solid black;border-width:2px 1px 1px 1px;background-color:Template:Element color;" | C 6

style="border:solid black;border-width:2px 1px 1px 1px;background-color:Template:Element color;" | N 7

style="border:solid black;border-width:2px 1px 1px 1px;background-color:Template:Element color;" | O 8

style="border:solid black;border-width:2px 1px 1px 1px;background-color:Template:Element color;" | F 9

style="border:solid black;border-width:2px 2px 1px 1px;background-color:Template:Element color;" | Ne 10

3

Na 11

Mg 12

Template:Nowrap

Al 13

Si 14

P 15

S 16

Cl 17

Ar 18

4

K 19

Ca 20

style="border:solid black;border-width:1px 1px 1px 1px;background-color:Template:Element color;" | Sc-Zn 21-30

Ga 31

Ge 32

As 33

Se 34

Br 35

Kr 36

5

Rb 37

Sr 38

Template:Nowrap

Y-Cd 39-48

In 49

Sn 50

Sb 51

Te 52

I 53

Xe 54

6

Cs 55

Ba 56

style="border:solid black;border-width:1px 1px 1px 1px;background-color:Template:Element color;" | La-Yb 57-70

Lu-Hg 71-80

Tl 81

Pb 82

Bi 83

Po 84

At 85

Rn 86

7

Fr 87

Ra 88

Ac-No 89-102

Lr-Cn 103-112

Nh 113

Fl 114

Mc 115

Lv 116

Ts 117

Og 118

Group

(1)

(2)

(3-12)

(13)

(14)

(15)

(16)

(17)

(18)

The first-row anomaly strength by block is s >> p > d > f.<ref>Jensen 1986, p. 506</ref>Template:Efn

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 high polarizing power.<ref>Lee 1996, p. 240</ref> 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.<ref>Greenwood & Earnshaw 2002, p. 43</ref> 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."<ref>Cressey 2010</ref>

Hydrogen and helium, as well as boron through neon, have small atomic radii. The ionization energies and electronegativities among these elements are higher than the periodic trends would otherwise suggest.

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.<ref>Petruševski & Cvetković 2018; Grochala 2018</ref>

Secondary periodicity

File:EN values of chalcogens.png

Electronegativity values of the group 16 chalcogen elements showing a W-shaped alternation or secondary periodicity going down the group

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.<ref>Kneen, Rogers & Simpson 1972, pp. 226, 360; Siekierski & Burgess 2002, pp. 52, 101, 111, 124, 194</ref>Template:Efn 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 Template:Interlanguage link gives two more tangible examples:<ref>Shchukarev 1977, p. 229</ref>

"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 [[[:Template:Chem2]]] to bring metallic gold [Au] into solution, and the absence of this property in sulfuric [[sulfuric acid|[[[:Template:Chem2]]]]] and [[telluric acid|[[[:Template:Chem2]]]]] 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.Template:Efn 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.<ref name="Cox" />

Multiple bond formation

File:Pentazenium.png

Molecular structure of pentazenium, a homopolyatomic cation of nitrogen with the formula N₅⁺ and structure N−N−N−N−N.<ref>Vij et al. 2001</ref>

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,<ref name="Cox">Cox 2004, p. 146</ref> 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<ref>Dorsey 2023, pp. 12–13</ref> (although not as yet more precise quantum chemistry) Humphrey<ref>Humphrey 1908</ref> 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.

File:Brown-boron.jpg

Boron (here in its less stable amorphous form) shares some similarities with metalsTemplate:Efn

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);<ref name="AylwardEN"/>
• The electrical conductivity of graphite exceeds that of some metals;Template:Efn
• Selenium can be drawn into a wire;<ref name="ReferenceF"/>
• Radon is the most metallic of the noble gases and begins to show some cationic behavior, which is unusual for a nonmetal;<ref>Stein 1983, p. 165</ref> and
• In extreme conditions, just over half of nonmetallic elements can form homopolyatomic cations.Template:Efn

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,<ref>Schweitzer & Pesterfield 2010, p. 305</ref> and predominately acidic oxides.<ref name="Porterfield"/><ref>Rieck 1967, p. 97: Tungsten trioxide dissolves in hydrofluoric acid to give an oxyfluoride complex.</ref>
• 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.<ref>Wiberg 2001, p. 1279</ref> The reason for this is that gold has a large enough nuclear potential that the electrons have to be considered with relativistic effects included, which changes some of the properties.<ref>Template:Cite journal</ref>

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.<ref>Power 2010; Crow 2013; Weetman & Inoue 2018</ref>

Types Template:Anchor

Nonmetal classification schemes vary widely, with some accommodating as few as two subtypes and others 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".<ref>Encyclopaedia Britannica 2021</ref> On the other hand, seven of twelve color categories on the Royal Society of Chemistry periodic table include nonmetals.<ref>Royal Society of Chemistry 2021</ref>Template:Efn

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

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

Template:Legend inline the inert noble gases—helium, neon, argon, krypton, xenon, radon;<ref name="Matson"/>

Template:Legend inline the reactive halogen nonmetals—fluorine, chlorine, bromine, iodine;<ref>Kernion & Mascetta 2019, p. 191; Cao et al. 2021, pp. 20–21; Hussain et al. 2023; also called "nonmetal halogens": Chambers & Holliday 1982, pp. 273–274; Bohlmann 1992, p. 213; Jentzsch & Matile 2015, p. 247 or "stable halogens": Vassilakis, Kalemos & Mavridis 2014, p. 1; Hanley & Koga 2018, p. 24; Kaiho 2017, ch. 2, p. 1</ref> and

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

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

Template:Legend inline the generally unreactiveTemplate:Efn metalloids,<ref name="Moeller">Moeller et al. 1989, p. 742</ref> sometimes considered a third category distinct from metals and nonmetals—boron, silicon, germanium, arsenic, antimony, tellurium.

Template:Quote box The boundaries between these types are not sharp.Template:Efn 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".<ref>Russell & Lee 2005, p. 419</ref> Some consider metalloids distinct from both metals and nonmetals, while others classify them as nonmetals.<ref name="Goodrich etc">Goodrich 1844, p. 264; The Chemical News 1897, p. 189; Hampel & Hawley 1976, pp. 174, 191; Lewis 1993, p. 835; Hérold 2006, pp. 149–50</ref> Some categorize certain metalloids as metals (e.g., arsenic and antimony due to their similarities to heavy metals).<ref>Tyler 1948, p. 105; Reilly 2002, pp. 5–6</ref>Template:Efn Metalloids resemble the elements universally considered "nonmetals" in having relatively low densities, high electronegativity, and similar chemical behavior.<ref name="Moeller"/>Template:Efn

Noble gases

{{#invoke:Labelled list hatnote|labelledList|Main article|Main articles|Main page|Main pages}}

File:Argon ice 1.jpg

A small (about 2 cm long) piece of rapidly melting argon ice

Six nonmetals are classified as noble gases: helium, neon, argon, krypton, xenon, and the radioactive radon. In conventional periodic tables they occupy the rightmost column. They are called noble gases due to their exceptionally low chemical reactivity.<ref name="Matson">Matson & Orbaek 2013, p. 203</ref>

These elements exhibit similar properties, being colorlessness, odorless, and nonflammable. Due to their closed outer electron shells, noble gases possess weak interatomic forces of attraction, leading to exceptionally low melting and boiling points.<ref>Jolly 1966, p. 20</ref>

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,<ref>Maosheng 2020, p. 962</ref> with most of these compounds involving the combination of oxygen or fluorine with either krypton, xenon, or radon.<ref>Mazej 2020</ref>

Halogen nonmetals

{{#invoke:Labelled list hatnote|labelledList|Main article|Main articles|Main page|Main pages}}Chemically, the halogen nonmetals have high ionization energies, electron affinities, and electronegativity values, and are relatively strong oxidizing agents.<ref name="oxidizing">Rudolph 1973, p. 133: "Oxygen and the halogens in particularTemplate:Nbsp... are therefore strong oxidizing agents."</ref> All four elements tend to form primarily ionic compounds with metals,<ref name="Cotton">Cotton et al. 1999, p. 554</ref> in contrast to the remaining nonmetals (except for oxygen) which tend to form primarily covalent compounds with metals.Template:Efn

Unclassified nonmetals

File:Selenium black (cropped).jpg

Selenium conducts electricity around 1,000 times better when light falls on it, a property used in light-sensing applications.<ref>Emsley 2011, p. 478</ref>

Template:AnchorHydrogen behaves in some respects like a metallic element and in others like a nonmetal.<ref>Seese & Daub 1985, p. 65</ref> Like a metallic element it can, for example, form a solvated cation in aqueous solution;<ref>MacKay, MacKay & Henderson 2002, pp. 209, 211</ref> 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<ref>Cousins, Davidson & García-Vivó 2013, pp. 11809–11811</ref><ref name="Cao4">Cao et al. 2021, p. 4</ref> as a nonmetal.<ref>Liptrot 1983, p. 161; Malone & Dolter 2008, p. 255</ref> It attains this configuration by forming a covalent or ionic bond<ref name="Wiberg255–257">Wiberg 2001, pp. 255–257</ref> or by bonding as an ion to a lone pair of electrons.<ref>Scott & Kanda 1962, p. 153</ref>

Some or all of these nonmetals share several properties. Being generally less reactive than the halogens,<ref>Taylor 1960, p. 316</ref> most of them can occur naturally in the environment.<ref name="Emsley"/> Collectively, their physical and chemical characteristics can be described as "moderately non-metallic".<ref name="Cao20">Cao et al. 2021, p. 20</ref> When combined with metals, the unclassified nonmetals can form interstitial or refractory compounds.<ref>Messler 2011, p. 10</ref> They also exhibit a tendency to bond to themselves, particularly in solid compounds.<ref>King 1994, p. 1344; Powell & Tims 1974, pp. 189–191; Cao et al. 2021, pp. 20–21</ref> Additionally, diagonal periodic table relationships among these nonmetals mirror similar relationships among the metalloids.<ref>Vernon 2020, pp. 221–223; Rayner-Canham 2020, p. 216</ref>

Abundance, extraction, and uses

Abundance

Approximate composition
Template:Nobold

Universe<ref>Chandra X-ray Center 2018</ref>	75% *hydrogen	23% *helium	1% *oxygen
Atmosphere<ref>Chapin, Matson & Vitousek 2011, p. 27</ref>	78% *nitrogen	21% *oxygen	0.5% *argon
Hydrosphere<ref name=Fortescue>Fortescue 1980, p. 56</ref>	86% *oxygen	11% *hydrogen	2% *chlorine
Biomass<ref>Georgievskii 1982, p. 58</ref>	63% *oxygen	20% *carbon	10% *hydrogen
Crust<ref name=Fortescue/>	46% *oxygen	27% *silicon	8% aluminium
Earth<ref name=":2">Morgan & Anders 1980, p. 6975</ref>	32% iron	30% *oxygen	14% magnesium

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 upon their overall abundance due to cosmic nucleosynthesis. Mechanisms to explain this difference is an important aspect of planetary science.<ref>Template:Cite journal</ref> The element Template:Abbr is unexpectedly depleted, and a possible explanation comes from theoretical models of the high pressures in the Earth's core suggesting that there may be around 10¹³ tons of xenon in the form of stable XeFe₃ and XeNi₃ intermetallic compounds.<ref>Zhu et al. 2014, pp. 644–648</ref>

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 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."<ref>Klein & Dutrow 2007, p. 435Template:Broken anchor</ref> However, they make up less than 50% of the total weight of the earth.<ref name=":2" />

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."<ref>Cockell 2019, p. 212, 208–211</ref>

Extraction

Nine of the 23 nonmetallic elements are gases, or form compounds that are gases, and are extracted from natural gas or liquid air, including hydrogen, nitrogen, oxygen, sulfur, and most of the noble gases. For example, nitrogen and oxygen are extracted from liquid air through fractional distillation<ref>Emsley 2011, pp. 363, 379</ref> and sulfur from the hydrogen sulfide in natural gas by reacting it with oxygen to yield water and sulfur.<ref>Emsley 2011, p. 516</ref> Three nonmetals are extracted from seawater; the rest of the nonmetals – and almost all metals – from mining solid ores.Template:Cn

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

Template:Nowrap are extracted from these sources:<ref name="Emsley">Emsley 2011, passim</ref>

Template:Legend inlinefrom natural gas components

hydrogen (methane), helium, and sulfur (hydrogen sulfide)

Template:Legend inlinefrom liquefied air

nitrogen, oxygen, neon, argon, krypton, and xenon

Template:Legend inlinefrom seawater brine

chlorine, bromine, and iodine

Template:Legend inlinefrom solid ores

boron (borates), carbon (natural graphite), silicon (silica), phosphorus (phosphates), iodine (sodium iodate), radon (uranium ore decay product), fluorine (fluorite); and germanium, arsenic, selenium, antimony, and tellurium (from their sulfides).

Uses

File:Argon.jpg

Cylinders containing argon gas for use in extinguishing fire without damaging computer server equipment

Nonmetallic elements are present in combination with other elements in almost everything around us, from water to plastics and within metallic alloys. There are some specific uses of the elements themselves, although these are less common; extensive details can be found in the specific pages of the relevant elements. A few examples are:

1. Hydrogen can be used in fuel cells, and is being explored for a possible future low-carbon hydrogen economy.<ref>Template:Cite journal</ref>
2. Carbon has many uses, ranging from decorative applications of diamond jewelry<ref>Template:Cite journal</ref> to diamond in cutting blades<ref>Template:Cite book</ref> and graphite as a solid lubricant.<ref name=":1" />
3. Liquid nitrogen is extensively used as a coolant.<ref>{{#invoke:citation/CS1|citation

|CitationClass=web }}</ref>

1. Oxygen is a critical component of the air we breath. (While nitrogen is also present, it is less used from the air, mainly by certain bacteria.<ref>Template:Cite journal</ref>) Oxygen gas and liquid is also heavily used for combustion in welding and cutting torches and as a component of rocket fuels.<ref>{{#invoke:citation/CS1|citation

|CitationClass=web }}</ref>

1. Silicon is the most widely used semiconductor. While ultra-pure silicon is an insulator, by selectively adding electronic dopants it can be used as a semiconductor where the chemical potential of the electrons can be manipulated, this being exploited in a wide range of electronic devices.<ref name=":0" />
2. The noble gases have a range of applications, including liquid helium for cryogenic cooling,<ref>{{#invoke:citation/CS1|citation

|CitationClass=web }}</ref> and argon to in gaseous fire suppression to -damp fires around sensitive electrical equipment where water cannot be used.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>

1. Radon is a potentially hazardous indoor pollutant.<ref>Maroni 1995, pp. 108–123</ref>

Taxonomical history

Background

Medieval chemical philosophers focused on metals, rarely investigating nonmetallic minerals.<ref>Stillman 1924, p. 213</ref>

Organization of elements by types

Template:See also In the late 1700s, French chemist Antoine Lavoisier published the first modern list of chemical elements in his revolutionary<ref>Strathern 2000, p. 239</ref> 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,<ref name=Moore1918>Template:Cite book Lavoisier's Table is reproduced on page 99.</ref> and earths (heat-resistant oxides).<ref>Criswell 2007, p. 1140</ref> 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.<ref>Salzberg 1991, p. 204</ref> Lavoisier's chemistry was "dualistic",: "salts" were combinations of "acid" and "base"; acids where combinations of oxygen and metals while bases where combinations of oxygen and nonmetals. This view prevailed despite increasing evidence that chemicals like chlorine and ammonia contained no oxygen, in large part due the vigious if sometimes misguided defense by the Swedish chemist Berzelius.<ref name=Moore1918/>Template:Rp

In 1802 the term "metalloids" was introduced for elements with the physical properties of metals but the chemical properties of non-metals.<ref name="Friend1953">Friend JN 1953, Man and the Chemical Elements, 1st ed., Charles Scribner's Sons, New York</ref> In 1811 Berzelius used the term "metalloids"<ref>Berzelius 1811, p. 258</ref> to describe all nonmetallic elements, noting their ability to form negatively charged ions with oxygen in aqueous solutions.<ref>Partington 1964, p. 168</ref><ref name="B1832">Bache 1832, p. 250</ref> Drawing on this, in 1864 the "Manual of Metalloids" divided all elements into either metals or metalloids, with the latter group including elements now called nonmetals.<ref>Apjohn, J. (1864). Manual of the Metalloids. United Kingdom: Longman.</ref>Template:Rp Reviews of the book indicated that the term "metalloids" was still endorsed by leading authorities,<ref name="Thechemical1864">The Chemical News and Journal of Physical Science 1864</ref> but there were reservations about its appropriateness. While Berzelius' terminology gained significant acceptance,<ref name="goldsmith">Goldsmith 1982, p. 526</ref> it later faced criticism from some who found it counterintuitive,<ref name="B1832"/> misapplied,<ref name=r4>Roscoe & Schormlemmer 1894, p. 4</ref> or even invalid.<ref>Glinka 1960, p. 76</ref> The idea of designating elements like arsenic as metalloids had been considered.<ref name="Thechemical1864"/> The use of the term "metalloids" persisted in France as textbooks of chemistry appeared in the 1800s. During this period, "metals" as a chemical category were characterized by a single property, their affinity for oxygen, while "metalloids" were organized by comparison of many characteristic analogous to the approach of naturalists.<ref>Bertomeu-Sánchez et al. 2002, pp. 235</ref>

Development of types

File:Lyon 1er - Place Gabriel Rambaud - Monument aux Grands Hommes de la Martinière - Gaspard Alphonse Dupasquier (medaillon).jpg

Bust of Dupasquier (1793–1848) in the Template:Ill in Lyon, France.

In 1844, Template:Ill, a French doctor, pharmacist, and chemist,<ref>Bertomeu-Sánchez et al. 2002, pp. 248–249</ref> established a basic taxonomy of nonmetals to aid in their study. He wrote:<ref>Dupasquier 1844, pp. 66–67</ref>

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.<ref>Bache 1832, pp. 248–276</ref> The boroids eventually evolved into the metalloids, with this classification beginning from as early as 1864.<ref name="Thechemical1864"/> The then unknown noble gases were recognized as a distinct nonmetal group after being discovered in the late 1800s.<ref>Renouf 1901, pp. 268</ref> This taxonomy was noted as a "natural classification" of the substance considering all aspects rather than an single characteristic like oxygen affinity.<ref>Bertomeu-Sánchez et al. 2002, p. 236</ref> It was a significant departure from other contemporary classifications, since it grouped together oxygen, nitrogen, hydrogen, and carbon.<ref>Hoefer 1845, p. 85</ref>

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,<ref>Dumas 1828; Dumas 1859</ref> 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.

Nonmetals as terminology

By as early as 1866, some authors began preferring the term "nonmetal" over "metalloid" to describe nonmetallic elements.<ref>Oxford English Dictionary 1989</ref> In 1875, Kemshead<ref>Kemshead 1875, p. 13</ref> 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.

Structure, quantum mechanics and band structure

The early terminologies were empirical categorizations based upon observables. As the 20th century started there were significant changes in understanding. The first was due to methods, mainly x-ray crystallography, for determining how atoms are arranged in the various materials. As early as 1784 René Just Haüy discovered that every face of a crystal could be described by simple stacking patterns of blocks of the same shape and size (law of decrements).<ref>Template:Cite book</ref> Haüy's study led to the idea that crystals are a regular three-dimensional array (a Bravais lattice) of atoms and molecules, with a single unit cell repeated indefinitely, along with other developments in the early days of physical crystallography. After Max von Laue demonstrated in 1912 that x-rays diffract,<ref>Template:Cite journal</ref> fairly quickly William Lawrence Bragg and his father William Henry Bragg were able to solve previously unknown structures.<ref>Template:Cite journal</ref><ref>Template:Cite journal</ref><ref>Template:Cite journal</ref> Building on this, it became clear that most of the simple elemental metals had close packed structures. With this determined the concept of dislocations originally developed by Vito Volterra in 1907<ref>Vito Volterra (1907) "Sur l'équilibre des corps élastiques multiplement connexes", Annales Scientifiques de l'École Normale Supérieure, Vol. 24, pp. 401–517</ref> became accepted, for instance being used to explain the ductility of metals by G. I. Taylor in 1934.<ref>Template:Cite journal</ref>

The second was the advent of quantum mechanics. In 1924 Louis de Broglie in his PhD thesis Recherches sur la théorie des quanta<ref name="Broglie">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> introduced his theory of electron waves. This rapidly became part of what was called by Erwin Schrödinger undulatory mechanics,<ref name="Schroedinger">Template:Cite journal</ref> now called the Schrödinger equation, wave mechanics or more commonly in contemporary usage quantum mechanics. While it was not so easy to solve the mathematics in the early days, fairly rapidly ideas such as the chemical bond terminology of Linus Pauling<ref>Template:Cite book</ref> as well as electronic band structure concepts were developed.<ref name=":0">Template:Cite book</ref>Template:Band structure filling diagramFrom this the concept of nonmetals as "not-a-metal" originates. The original approach to describe metals and nonmetals was a band-structure with delocalized electrons (i.e. spread out in space). A nonmetal has a gap in the energy levels of the electrons at the Fermi level.<ref name=":0" />Template:Rp In contrast, a metal would have at least one partially occupied band at the Fermi level;<ref name=":0" /> in a semiconductor or insulator there are no delocalized states at the Fermi level, see for instance Ashcroft and Mermin.<ref name=":0" /> (A semimetal is similar to a metal, with a slightly more complex band structure.) These definitions are equivalent to stating that metals conduct electricity at absolute zero, as suggested by Nevill Francis Mott,<ref name=":3">Template:Cite book</ref>Template:Rp and the equivalent definition at other temperatures is also commonly used as in textbooks such as Chemistry of the Non-Metals by Ralf Steudel<ref>Template:Cite book</ref> and work on metal–insulator transitions.<ref>Template:Cite journal</ref><ref>Template:Cite journal</ref>

Originally<ref>Template:Cite journal</ref><ref>Template:Cite journal</ref> this band structure interpretation was based upon a single-electron approach with the Fermi level in the band gap as illustrated in the Figure, not including a complete picture of the many-body problem where both exchange and correlation terms matter, as well as relativistic effects such as spin-orbit coupling. For instance, the passivity of gold is typically associated with relativistic terms.<ref>Template:Cite journal</ref> A key addition by Mott and Rudolf Peierls was that these could not be ignored.<ref>Template:Cite journal</ref> For instance, nickel oxide would be a metal if a single-electron approach was used, but in fact has quite a large band gap.<ref>Template:Cite journal</ref> As of 2024 it is more common to use an approach based upon density functional theory where the many-body terms are included.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref><ref>Template:Cite book</ref> Although accurate calculations remain a challenge, reasonable results are now available in many cases.<ref>Template:Cite journal</ref><ref>Template:Cite journal</ref>

It is common to nuance the early definition of Alan Herries Wilson and Mott which was for a zero temperature. As discussed by Peter Edwards and colleagues,<ref>Template:Cite journal</ref> as well as Fumiko Yonezawa,<ref name=":3" />Template:Rpit is important to consider the temperatures at which both metals and nonmetals are used. Yonezawa provides a general definition for both general temperatures and conditions (such as standard temperature and pressure):<ref name=":3" />Template:Rp

The precise meaning of semiconductor needs a little care. In terms of the temperature dependence of their conductivity they are all classified as insulators; the pure forms are intrinsic semiconductors. When they are doped their conductivity continues to increase with temperature,<ref name=":0" /> and can become substantial; hence the ambiguities with an empirical categorisation using conductivity described earlier. Indeed, some elements that are normally considered as insulators have been exploited as semiconductors. For instance diamond, which has the largest band gap of the elements that are solids under normal conditions,<ref>Template:Cite journal</ref> has a number of semiconductor applications.<ref>Template:Cite journal</ref><ref>Template:Cite journal</ref>

Band structure definitions of metals and nonmetals are widely used in current research into materials, and apply both to single elements such as insulating boron<ref>Template:Cite journal</ref> as well as compounds such as strontium titanate.<ref>Template:Cite journal</ref> The characteristics associated with metals and nonmetals in early work such as their appearance and mechanical properties are now understood to be consequences of how the atoms and electrons are arranged.

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

{{#invoke:Hatnote|hatnote}}

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

Property	Element type
	Metals	Metalloids	Unc. nonmetals	Halogen nonmetals	Noble gases
General physical appearance	lustrous<ref name="Kneen"/>	lustrous<ref name="Rochow 1966, p. 4">Rochow 1966, p. 4</ref>	Template:Indented plainlist	Template:Indented plainlist	colorless<ref>Kneen, Rogers & Simpson 1972, p. 308</ref>
Form and density<ref>Tregarthen 2003, p. 10</ref>	solid (Hg liquid)	solid	solid or gas	solid or gas (bromine liquid)	gas
	often high density such as iron, lead, tungsten	low to moderately high density	low density	low density	low density
	some light metals including beryllium, magnesium, aluminium	all lighter than iron	hydrogen, nitrogen lighter than air<ref>Lewis 1993, pp. 28, 827</ref>		helium, neon lighter than air<ref>Lewis 1993, pp. 28, 813</ref>
Plasticity	mostly malleable and ductile<ref name="Kneen"/>	often brittle<ref name="Rochow 1966, p. 4" />	phosphorus, sulfur, selenium, brittleTemplate:Efn	iodine brittle<ref>Wiberg 2001, p. 416</ref>	not applicable
Electrical conductivity	goodTemplate:Efn	Template:Indented plainlist	Template:Indented plainlist	Template:Indented plainlist	poorTemplate:Efn
Electronic structure<ref name="K&W">Keeler & Wothers 2013, p. 293</ref>	metal (beryllium, strontium, α-tin, ytterbium, bismuth are semimetals)	semimetal (arsenic, antimony) or semiconductor	Template:Indented plainlist	semiconductor (Template:Abbr) or insulator	insulator

Chemical properties by element type

{{#invoke:Hatnote|hatnote}}

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

Property	Element type
	Metals	Metalloids	Unc. nonmetals	Halogen nonmetals	Noble gases
General chemical behavior	Template:Indented plainlist	weakly nonmetallicTemplate:Efn	moderately nonmetallic<ref name="W2009">Welcher 2009, p. 3–32: "The elements change fromTemplate:Nbsp... metalloids, to moderately active nonmetals, to very active nonmetals, and to a noble gas."</ref>	strongly nonmetallic<ref>Mackin 2014, p. 80</ref>	Template:Indented plainlist
Oxides	basic; some amphoteric or acidic<ref name="Porterfield">Porterfield 1993, p. 336</ref>	amphoteric or weakly acidic<ref>Rochow 1966, p. 4; Atkins et al. 2006, pp. 8, 122–123</ref>Template:Efn	acidicTemplate:Efn or neutralTemplate:Efn	acidicTemplate:Efn	metastable XeO3 is acidic;<ref>Wiberg 2001, p. 399</ref> stable XeO4 strongly so<ref>Kläning & Appelman 1988, p. 3760</ref>
	few glass formersTemplate:Efn	all glass formers<ref>Sidorov 1960, pp. 599–603</ref>	some glass formersTemplate:Efn	no glass formers reported	no glass formers reported
	ionic, polymeric, layer, chain, and molecular structures<ref>Wells 1984, p. 534</ref>	polymeric in structure<ref name="Pudd">Puddephatt & Monaghan 1989, p. 59</ref>	Template:Indented plainlist	Template:Indented plainlist	Template:Indented plainlist
Compounds with metals	alloys<ref name="Kneen"/> or intermetallic compounds<ref>Yamaguchi & Shirai 1996, p. 3</ref>	tend to form alloys or intermetallic compounds<ref>Vernon 2020, p. 223</ref>	Template:Indented plainlist	mainly ionic<ref name="Cotton"/>	simple compounds at STP not knownTemplate:Efn
Ionization energy (kJ mol−1)<ref name="AylwardIE">Aylward & Findlay 2008, p. 132</ref> ‡	low to high	moderate	moderate to high	high	high to very high
	376 to 1,007	762 to 947	941 to 1,402	1,008 to 1,681	1,037 to 2,372
	average 643	average 833	average 1,152	average 1,270	average 1,589
Electronegativity (Pauling)Template:Efn<ref name="AylwardEN">Aylward & Findlay 2008, p. 126</ref> ‡	low to high	moderate	moderate to high	high	high (radon) to very high
	0.7 to 2.54	1.9 to 2.18	2.19 to 3.44	2.66 to 3.98	ca. 2.43 to 4.7
	average 1.5	average 2.05	average 2.65	average 3.19	average 3.3

† Hydrogen can also form alloy-like hydrides<ref name="Cao4"/>
‡ 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

References

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