 Bismuth is a chemical element with the symbol Bi and the atomic number 83 . Bismuth , a pentavalent post @-@ transition metal , chemically resembles 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 . It is a brittle metal with a silvery white color when freshly produced , but is often seen in air with a pink tinge owing to surface oxidation . Bismuth is the most naturally diamagnetic element , and has one of the lowest values of thermal conductivity among metals . 
