Bismuth is a chemical element with the symbol Bi and atomic number 83. It is a pentavalent post-transition metal and one of the pnictogens with chemical properties resembling its lighter group 15 siblings arsenic and antimony. Elemental bismuth may occur naturally, although its sulfide and oxide form important commercial ores. The free element is 86% as dense as lead. When freshly produced, it is a brittle metal with a silvery-white color, but surface oxidation can give it an iridescent tinge in numerous colors. Bismuth is the most naturally diamagnetic element and has one of the lowest thermal conductivity values among metals.
A pnictogen is one of the chemical elements in group 15 of the periodic table. This group is also known as the nitrogen family. The chalcogens are the chemical elements in group 16 of the periodic table. This group is also known as the oxygen family.
Pnictogens consist of the elements nitrogen (N), phosphorus (P), arsenic (As), antimony (Sb), bismuth (Bi), and perhaps the chemically uncharacterized synthetic element moscovium (Mc).