Properties of nonmetals (and metalloids) by group
From Wikipedia, the free encyclopedia
Nonmetals show more variability in their properties than do metals.[1] Metalloids are included here since they behave predominately as chemically weak nonmetals.
This article needs additional citations for verification. (July 2021) |
Physically, they nearly all exist as diatomic or monatomic gases, or polyatomic solids having more substantial (open-packed) forms and relatively small atomic radii, unlike metals, which are nearly all solid and close-packed, and mostly have larger atomic radii. If solid, they have a submetallic appearance (with the exception of sulfur) and are brittle, as opposed to metals, which are lustrous, and generally ductile or malleable; they usually have lower densities than metals; are mostly poorer conductors of heat and electricity; and tend to have significantly lower melting points and boiling points than those of most metals.
Chemically, the nonmetals mostly have higher ionisation energies, higher electron affinities (nitrogen and the noble gases have negative electron affinities) and higher electronegativity values[n 1] than metals noting that, in general, the higher an element's ionisation energy, electron affinity, and electronegativity, the more nonmetallic that element is.[2] Nonmetals, including (to a limited extent) xenon and probably radon, usually exist as anions or oxyanions in aqueous solution; they generally form ionic or covalent compounds when combined with metals (unlike metals, which mostly form alloys with other metals); and have acidic oxides whereas the common oxides of nearly all metals are basic.