Bismuth

タイトルまたは説明

Bismuth is a chemical element with symbol Bi and atomic number *3. Bismuth, a trivalent poor metal, resembles arsenic and antimony. Elemental bismuth may occur naturally uncombined, although its sulfide and oxide form important commercial ores. The free element is *6% as dense as lead, and brittle, with a silvery white color, and often a pink tinge owing to the surface oxide. Bismuth metal has been known from ancient times, although until the *8th century it was often confused with lead and tin, which each have some of the metal's physical properties. The name possibly comes from German words meaning "white mass."

Bismuth is the most naturally diamagnetic of all metals, and only mercury has a lower thermal conductivity.

Bismuth has classically been considered to be the heaviest naturally-occurring stable element. Recently, however, it has been found to be very slightly radioactive: it’s only naturally occurring isotope bismuth***9 decays via alpha decay into thallium***5 with a half-life of more than a billion times the estimated age of the universe.

Bismuth compounds are used in cosmetics, medicines, and in medical procedures. Bismuth has unusually low toxicity for a heavy metal. As the toxicity of lead has become more apparent in recent years, alloy uses for bismuth metal, as a replacement for lead, have become an increasing part of bismuth's commercial importance