In chemistry, a nonmetal
) is a chemical element
that 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 ionization 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).