{| style="float:right; margin-left:2.5em; margin-bottom:1.2em; font-size:95%; max-width: 450px; border:1px solid grey"
| style=text-align:center|A periodic table extract
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| [[File:Nonmetals in the periodic table.png|450px| 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.]]
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| style="padding-left:5px; font-size:95%;"|always/usually considered nonmetals
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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).
thumb|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.|alt=Two dull silver clusters of crystalline shards.]]
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. any list of nonmetals is open to debate and revision.
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 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.<!-- It would be nice to say "due to the structure of their electrons" or something like that, as is mentioned w/r/t shiny solids and colorless gases, but nothing is stated about the electronics of the colored ones -->
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 the electrons reflecting 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 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. 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. 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.
{|class="wikitable floatright" style="line-height: 1.3; font-size: 95%; margin-left:20px; margin-bottom:1.2em"
|+ Some general physical differences<br />between elemental metals and nonmetals<br />all but one solid
|Shiny, colored or<br />transparent; all but<br />one solid or gaseous
| Good
| Poor to good
|-
| Electronic<br />structure 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.
Good electrical conductivity occurs when there is metallic bonding, however the electrons in some nonmetals are not metallic. 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, Some do deform such as white phosphorus (soft as wax, pliable and can be cut with a knife at room temperature), plastic sulfur, and 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
{|class="wikitable floatright" style="line-height: 1.3; font-size: 95%; margin-left:20px"
|+ Some general chemistry-based<br/>differences between metals and nonmetals
| colspan=2 style="text-align: center"| Wide range: very reactive to noble
|-
| rowspan =2 | Oxides || lower
| Basic
| rowspan =2 | Acidic; never basic
|-
| higher || Increasingly acidic
|-
| colspan=2 |Compounds<br />with metals
| Alloys
| Covalent or Ionic
|-
| colspan=2 | Ionization energy) or neutral (like nitrous oxide, N<sub>2</sub>O), 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.
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. 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, and a greater tendency of these elements to gain electrons during chemical reactions, forming negatively charged ions. 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. 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 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.
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
<div style="line-height:1px;">link=|alt=A table with seven rows and ten columns. Rows are labeled on the left with a period number from 1 through 7. Columns are labeled on the bottom with a group number. Most cells represent a single chemical element and have two lines of information: the element's symbol on the top and its atomic number on the bottom. The table as a whole is divided into four rectangular areas separated from each other by narrow gaps. The first rectangle fills all seven rows of the first two columns. The rectangle is labeled "s-block" at the top and its two columns are labeled with group numbers "(1)" and "(2)" on the bottom. The cells in the first row - hydrogen and helium, with symbols H and He and atomic numbers 1 and 2 respectively - are both shaded red. The second rectangle fills the bottom two rows (periods 6 and 7) of the third column. Just above these cells is the label "f-block"; there is no group label on the bottom. The topmost cell - labeled "La-Yb" for elements 57-70 - is shaded green. The third rectangle fills the bottom four rows (periods 4 through 7) of the fourth column. Just above these cells is the label "d-block"; at the bottom is the label "(3-12)" for the group numbers of these elements. The topmost cell - labeled "Sc-Zn" for elements 21-30 - is shaded blue. The fourth and last rectangle fills the bottom six rows (periods 2 through 7) of the last six columns. Just above these cells is the label "p-block"; at the bottom are labels "(13)" through "(18) for the group numbers of these elements. The cells in the topmost row - for the elements boron (B,5), carbon (C,6), nitrogen (N,7), oxygen (O,8), fluorine (Fl,9), and neon (Ne,10) - are shaded yellow. Bold lines encircle the cells of the nonmetals - the top two cells on the left and 21 cells in the upper right of the table.</div>
{| class=" floatright" style="border-collapse:collapse; text-align:center;font-size:80%;line-height:1.1;margin-top:1.2em;"
| colspan=14 style="padding-bottom:3px;border:none;text-align:center;font-size:105%" | Condensed periodic table highlighting<br />the first row of each block: and
|-
| colspan=1 | Period
| colspan=2 |
| rowspan=9 style="padding:1px;" |
| colspan=1 |
| rowspan=9 style="padding:1px;" |
| colspan=1 |
| rowspan=9 style="padding:1px;" |
| colspan=6 |
|-
| 1
| style="border:solid black;border-width:2px 1px 2px 2px;background-color:;" | H <br />1
| style="border:solid black;border-width:2px 2px 2px 1px;background-color:;" | He<br />2
|
|
| colspan=6 | <br />p-block
|-
| 2
| style="border:solid black;border-width:1px 1px 1px 1px;" | Li<br />3
| style="border:solid black;border-width:1px 1px 1px 1px;" | Be<br />4
|
|
| style="border:solid black;border-width:2px 1px 2px 2px;background-color:;" | B <br />5
| style="border:solid black;border-width:2px 1px 1px 1px;background-color:;" | C <br />6
| style="border:solid black;border-width:2px 1px 1px 1px;background-color:;" | N <br />7
| style="border:solid black;border-width:2px 1px 1px 1px;background-color:;" | O <br />8
| style="border:solid black;border-width:2px 1px 1px 1px;background-color:;" | F <br />9
| style="border:solid black;border-width:2px 2px 1px 1px;background-color:;" | Ne<br />10
|-
| 3
| style="border:solid black;border-width:1px 1px 1px 1px;" | Na<br />11
| style="border:solid black;border-width:1px 1px 1px 1px;" | Mg<br />12
|
| <br />
| style="border:solid black;border-width:1px 1px 1px 1px;" | Al<br />13
| style="border:solid black;border-width:1px 1px 1px 2px;" | Si<br />14
| style="border:solid black;border-width:1px 1px 1px 1px;" | P <br />15
| style="border:solid black;border-width:1px 1px 1px 1px;" | S <br />16
| style="border:solid black;border-width:1px 1px 1px 1px;" | Cl<br />17
| style="border:solid black;border-width:1px 2px 1px 1px;" | Ar<br />18
|-
| 4
| style="border:solid black;border-width:1px 1px 1px 1px;" | K <br />19
| style="border:solid black;border-width:1px 1px 1px 1px;" | Ca<br />20
|
| style="border:solid black;border-width:1px 1px 1px 1px;background-color:;" | Sc-Zn<br />21-30
| style="border:solid black;border-width:1px 1px 1px 1px;" | Ga<br />31
| style="border:solid black;border-width:1px 1px 2px 2px;" | Ge<br />32
| style="border:solid black;border-width:1px 1px 1px 1px;" | As<br />33
| style="border:solid black;border-width:1px 1px 1px 1px;" | Se<br />34
| style="border:solid black;border-width:1px 1px 1px 1px;" | Br<br />35
| style="border:solid black;border-width:1px 2px 1px 1px;" | Kr<br />36
|-
| 5
| style="border:solid black;border-width:1px 1px 1px 1px;" | Rb<br />37
| style="border:solid black;border-width:1px 1px 1px 1px;" | Sr<br />38
| <br />
| style="border:solid black;border-width:1px 1px 1px 1px;" | Y-Cd<br />39-48
| style="border:solid black;border-width:1px 1px 1px 1px;" | In<br />49
| style="border:solid black;border-width:1px 1px 1px 1px;" | Sn<br />50
| style="border:solid black;border-width:1px 1px 2px 2px;" | Sb<br />51
| style="border:solid black;border-width:1px 1px 2px 1px;" | Te<br />52
| style="border:solid black;border-width:1px 1px 2px 1px;" | I <br />53
| style="border:solid black;border-width:1px 2px 1px 1px;" | Xe<br />54
|-
| 6
| style="border:solid black;border-width:1px 1px 1px 1px;" | Cs<br />55
| style="border:solid black;border-width:1px 1px 1px 1px;" | Ba<br />56
| style="border:solid black;border-width:1px 1px 1px 1px;background-color:;" | La-Yb<br />57-70
| style="border:solid black;border-width:1px 1px 1px 1px;" | Lu-Hg<br />71-80
| style="border:solid black;border-width:1px 1px 1px 1px;" | Tl<br />81
| style="border:solid black;border-width:1px 1px 1px 1px;" | Pb<br />82
| style="border:solid black;border-width:1px 1px 1px 1px;" | Bi<br />83
| style="border:solid black;border-width:1px 1px 1px 1px;" | Po<br />84
| style="border:solid black;border-width:1px 1px 1px 1px;" | At<br />85
| style="border:solid black;border-width:1px 2px 2px 2px;" | Rn<br />86
|-
| 7
| style="border:solid black;border-width:1px 1px 1px 1px;" | Fr<br />87
| style="border:solid black;border-width:1px 1px 1px 1px;" | Ra<br />88
| style="border:solid black;border-width:1px 1px 1px 1px;" | Ac-No<br />89-102
| style="border:solid black;border-width:1px 1px 1px 1px;" | Lr-Cn<br />103-112
| style="border:solid black;border-width:1px 1px 1px 1px;" | Nh<br />113
| style="border:solid black;border-width:1px 1px 1px 1px;" | Fl<br />114
| style="border:solid black;border-width:1px 1px 1px 1px;" | Mc<br />115
| style="border:solid black;border-width:1px 1px 1px 1px;" | Lv<br />116
| style="border:solid black;border-width:1px 1px 1px 1px;" | Ts<br />117
| style="border:solid black;border-width:1px 1px 1px 1px;" | Og<br />118
|-
| Group
| (1)
| (2)
|
| (3-12)
| (13)
| (14)
| (15)
| (16)
| (17)
| (18)
|-
| colspan=14 style="border:none;"|
|-
| colspan=14 style="border:none; text-align:Center;font-size:105%;"| The first-row anomaly strength by block is s >> p > d > f.
|}
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. 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 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.
Secondary periodicity
thumb|upright=0.8|Electronegativity values of the group 16 [[chalcogen elements showing a W-shaped alternation or secondary periodicity going down the group|alt=A graph with a vertical electronegativity axis and a horizontal atomic number axis. The five elements plotted are , , , and . The electronegativity of looks too high, and causes a bump in what otherwise be a smooth curve.]]
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:
:<span style="font-size:95%">"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."</span>
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 NH<sub>3</sub>, hydrogen sulfide H<sub>2</sub>S, 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)O<sub>3</sub> and phosphorus pentafluoride PCl<sub>5</sub>. Higher oxidation states in later groups emerge from period 3 onwards, as seen in sulfur hexafluoride SF<sub>6</sub>, iodine heptafluoride IF<sub>7</sub>, and xenon(VIII) tetroxide XeO<sub>4</sub>. 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.]]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 (although not as yet more precise quantum chemistry) Humphrey observed that:
:<span style="font-size:95%">... 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.</span>
thumb|right|alt=An open glass jar with a brown powder in it|Boron (here in its less stable amorphous form) shares some similarities with 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);
- Selenium can be drawn into a wire; 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<sup>–</sup> 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. 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.
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 (H<sub>2</sub>), ammonia (NH<sub>3</sub>), and ethylene (C<sub>2</sub>H<sub>4</sub>), 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 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.
{| class="wikitable floatright" style="font-size:120%;text-align:center; line-height: 95%;border-color:black;"
|-style="font-size:70% ; line-height: 95%;"
| style="border:none"|
| colspan=1 style="border:none;" |
| colspan=4 style="border:none;" | Group (1, 13−18)
| colspan=2 style="border:none;text-align:right" | Period
|-style="font-size:70% ; line-height: 95%; vertical-align:top;"
| style="border:none"|
| scope="col" style="border:none; width: 22px" | 13
| scope="col" style="border:none; width: 22px" | 14
| scope="col" style="border:none; width: 22px" | 15
| scope="col" style="border:none; width: 22px" | 16
| scope="col" style="border:none; width: 22px" | <u>1</u>/17
| scope="col" style="border:none; width: 22px" | 18
| scope="col" style="border:none; width: 22px" |
|-
| style="border:none; line-height: 20px"|
| colspan=4 style="border:none" |
| style="background-color:#FFFFFF;border-bottom:2px solid black;border-right:2px solid black;" | H
| style="background-color:#9BCDFD;padding-bottom:3px;" | He
| style="border:none; font-size:70%;" | 1
|-
| style="border:none; line-height: 20px"|
| style="background-color:#FC9A9B;" | B
| style="background-color:#FFFFFF;" | C
| style="background-color:#FFFFFF;" | N
| style="background-color:#FFFFFF;" | O
| style="background-color:#FFFD9F;" | F
| style="background-color:#9BCDFD;" | Ne
| style="border:none; font-size:70%" | 2
|-
| style="border:none; line-height: 20px"|
| style="border:none;" |
| style="background-color:#FC9A9B;" | Si
| style="background-color:#FFFFFF;" | P
| style="background-color:#FFFFFF;" | S
| style="background-color:#FFFD9F;" | Cl
| style="background-color:#9BCDFD;" | Ar
| style="border:none; font-size:70%" | 3
|-
| style="border:none; line-height: 20px"|
| style="border:none;" |
| style="background-color:#FC9A9B;" | Ge
| style="background-color:#FC9A9B;" | As
| style="background-color:#FFFFFF;" | Se
| style="background-color:#FFFD9F;" | Br
| style="background-color:#9BCDFD;" | Kr
| style="border:none; font-size:70%" | 4
|-
| style="border:none; line-height: 20px"|
| colspan=2 style="border:none;" |
| style="background-color:#FC9A9B;" | Sb
| style="background-color:#FC9A9B;" | Te
| style="background-color:#FFFD9F;" | I
| style="background-color:#9BCDFD;" | Xe
| style="border:none; font-size:70%" | 5
|-
| style="border:none; line-height: 20px"|
| colspan=5 style="border:none;" |
| style="background-color:#9BCDFD;" | Rn
| style="border:none; font-size:70%" | 6
|-
|-
| colspan=8 style="border:none;" |
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| colspan=8 |
{|
|
| style="border:none;font-size:70%;text-align:left;" |
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Starting on the right side of the periodic table, three types of nonmetals can be recognized:
<div style="margin-left:2em; text-indent:-2em;">
the relatively unreactive noble gases—helium, neon, argon, krypton, xenon, radon; and</div>
<div style="margin-left:2em; text-indent:-2em;">
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.</div>
The elements in a fourth set are sometimes recognized as nonmetals:
<div style="margin-left:2em; text-indent:-2em;">
the generally unreactive metalloids, sometimes considered a third category distinct from metals and nonmetals—boron, silicon, germanium, arsenic, antimony, tellurium.</div>
The boundaries between these types are not sharp.