Nonmetal

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For criticism see Criticism of Nonmetal

Nonmetal is a term used in chemistry when classifying the chemical elements. On the basis of their general physical and chemical properties, every element in the periodic table can be termed either a metal or a non-metal. (A few elements with intermediate properties are referred to as metalloids.)

The elements generally regarded as nonmetals are:

• hydrogen (H)
• In Group 14: carbon (C)
• In Group 15 (the pnictogens): nitrogen (N), phosphorus (P)
• Several elements in Group 16, the chalcogens: oxygen (O), sulfur (S), selenium (Se)
• All elements in Group 17 - the halogens
• All elements in Group 18 - the noble gases

There is no rigorous definition for the term "nonmetal" - it covers a general spectrum of behaviour. Common properties considered characteristic of a nonmetal include:

• poor conductors of heat and electricity when compared to metals
• they form acidic oxides (whereas metals generally form basic oxides)
• in solid form, they are dull and brittle, rather than metals which are lustrous, ductile or malleable
• usually have lower densities than metals
• they have significantly lower melting points and boiling points than metals
• non-metals have high electronegativity

Only eighteen elements in the periodic table are generally considered nonmetals, compared to over eighty metals, but nonmetals make up most of the crust, atmosphere and oceans of the earth. Bulk tissues of living organisms are composed almost entirely of nonmetals. Most nonmetals form monatomic or diatomic molecules in their elemental state, unlike metals which (in their elemental state) do not form molecules at all.

Metallisation at huge pressures

Nevertheless, even these 20 elements tend to become metallic at large enough pressures (see nearby periodic table at ~300 GPa).

See also

v • d • e Periodic tables Layouts Standard · Vertical · Full names · Names and atomic masses · Text for last · Huge table · Metals and nonmetals · Blocks · Valences · Inline f-block · 218 elements · Electron configurations · Atomic masses · Electronegativities · Alternatives Lists of elements Name · Atomic symbol · Atomic number · Boiling point · Melting point · Density · Atomic mass Groups 1 · 2 · 3 · 4 · 5 · 6 · 7 · 8 · 9 · 10 · 11 · 12 · 13 · 14 · 15 · 16 · 17 · 18 Periods: 1 · 2 · 3 · 4 · 5 · 6 · 7 · 8 Element categories Alkalis · Alkaline earths · Lanthanides · Actinides · Transition metals · Metals · Metalloids · Nonmetals · Halogens · Noble gases Blocks s-block · p-block · d-block · f-block · g-block

This box: view • talk • edit Periodic table
H																															He
Li	Be																									B	C	N	O	F	Ne
Na	Mg																									Al	Si	P	S	Cl	Ar
K	Ca															Sc	Ti	V	Cr	Mn	Fe	Co	Ni	Cu	Zn	Ga	Ge	As	Se	Br	Kr
Rb	Sr															Y	Zr	Nb	Mo	Tc	Ru	Rh	Pd	Ag	Cd	In	Sn	Sb	Te	I	Xe
Cs	Ba	La	Ce	Pr	Nd	Pm	Sm	Eu	Gd	Tb	Dy	Ho	Er	Tm	Yb	Lu	Hf	Ta	W	Re	Os	Ir	Pt	Au	Hg	Tl	Pb	Bi	Po	At	Rn
Fr	Ra	Ac	Th	Pa	U	Np	Pu	Am	Cm	Bk	Cf	Es	Fm	Md	No	Lr	Rf	Db	Sg	Bh	Hs	Mt	Ds	Rg	Uub	Uut	Uuq	Uup	Uuh	Uus	Uuo
Alkali metals Alkaline earth metals Lanthanoids Actinoids Transition metals Other metals Metalloids Other nonmetals Halogens Noble gases

This page uses content from Wikipedia. The original article was at Nonmetal. The list of authors can be seen in the page history. The text of this Wikinfo article is available under the GNU Free Documentation License.