• A chemical element which usually accepts electrons to form negative ions, whose oxides are acidic, and which tend to be poor conductors of heat and electricity, although some have semiconductor properties. At ordinary temperatures and pressures, a nonmetallic element may be a solid, such as carbon or silicon, a liquid, such as bromine, or a gas, such as oxygen or xenon. Some nonmetals, such as boron and carbon, have crystalline allotropic forms.
  • Any element or material which is not a metal.