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Bismuth is a chemical element with symbol Bi and 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. Bismuth metal has been known since ancient times, although until the 18th century it was often confused with lead and tin, which share some physical properties. The etymology is uncertain, but possibly comes from Arabic ''bi ismid'', meaning having the properties of antimony〔(Bismuth ). WebMineral. Retrieved on 17 December 2011.〕 or German words ''weisse masse'' or ''wismuth'' ("white mass"), translated in the mid-sixteenth century to New Latin ''bisemutum''.〔 Bismuth has long been considered as the element with the highest atomic mass that is stable. However, in 2003 it was discovered to be weakly radioactive: its only primordial isotope, bismuth-209, decays via alpha decay with a half life more than a billion times the estimated age of the universe. Bismuth compounds account for about half the production of bismuth. They are used in cosmetics, pigments, and a few pharmaceuticals, notably bismuth subsalicylate, used to treat diarrhea. Bismuth's unusual propensity to expand upon freezing is responsible for some of its uses, such as in casting of printing type. Bismuth has unusually low toxicity for a heavy metal. As the toxicity of lead has become more apparent in recent years, there is an increasing use of bismuth alloys (presently about a third of bismuth production) as a replacement for lead. == History == The name ''bismuth'' is from ca. 1660s, and is of uncertain etymology. It is one of the first 10 metals to have been discovered. Bismuth appears in the 1660s, from obsolete German ''ドイツ語:Bismuth'', ''ドイツ語:Wismut'', ''ドイツ語:Wissmuth'' (early 16th century); perhaps related to Old High German ' ("white"). The New Latin ''ラテン語:bisemutum'' (due to Georgius Agricola, who Latinized many German mining and technical words) is from the German ''ドイツ語:Wismuth'', perhaps from ''ドイツ語:weiße Masse'', "white mass". The element was confused in early times with tin and lead because of its resemblance to those elements. Bismuth has been known since ancient times, so no one person is credited with its discovery. Agricola, in De Natura Fossilium (ca. 1546) states that bismuth is a distinct metal in a family of metals including tin and lead. This was based on observation of the metals and their physical properties. Miners in the age of alchemy also gave bismuth the name ''ラテン語:tectum argenti,'' or "silver being made," in the sense of silver still in the process of being formed within the Earth.〔Giunta, Carmen J. (Glossary of Archaic Chemical Terms ), Le Moyne College. See also for other terms for bismuth, including ''stannum glaciale'' (glacial tin or ice-tin).〕 Beginning with Johann Heinrich Pott in 1738, Carl Wilhelm Scheele and Torbern Olof Bergman, the distinctness of lead and bismuth became clear, and Claude François Geoffroy demonstrated in 1753 that this metal is distinct from lead and tin.〔〔 Bismuth was also known to the Incas and used (along with the usual copper and tin) in a special bronze alloy for knives. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Bismuth」の詳細全文を読む スポンサード リンク
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