Chemists classify carbon as a nonmetal. It is one of only five elements normally found as solids that are not classified as metals, with the others being phosphorous, sulfur, selenium and iodine. On the periodic table, only 17 elements are classified as nonmetals, most of which normally exist as gases.
Metals are distinguished from nonmetals by a set of physical properties. Metals are good conductors of heat and electricity, while nonmetals tend to be better insulators. Metals tend to be malleable and ductile, while nonmetallic solids are brittle. Metals are generally lustrous, while nonmetals are dull. Metals are denser than nonmetals, and have higher melting points. While the vast majority of elements are classified as metals, two nonmetals, hydrogen and helium, make up over 99 percent of the observable universe.