In chemistry, a nonmetal or non-metal is a chemical element which mostly lacks metallic
attributes. Physically, nonmetals tend to be highly volatile (easily vaporised), have
low elasticity, and are good insulators of heat and electricity; chemically, they
tend to have high ionisation energy and electronegativity values, and gain or share
electrons when they react with other elements or compounds. Seventeen elements are
generally classified as nonmetals; most are gases (hydrogen, helium, nitrogen, oxygen,
fluorine, neon, chlorine, argon, krypton, xenon and radon); one is a liquid (bromine);
and a few are solids (carbon, phosphorus, sulfur, selenium, and iodine).