bismuti

Bismuth (Bi) is a chemical element with atomic number 83. It is a brittle post-transition metal with a pinkish-white hue when freshly cut. It has a relatively low melting point for a metal (271.4°C) and expands slightly on solidification. Bismuth is highly diamagnetic and usually occurs in the +3 oxidation state, with limited chemistry in the +5 state.

Occurrence and production: Bismuth occurs mainly in sulfidic and oxide minerals such as bismuthinite (Bi2S3) and bismite (Bi2O3). It is obtained largely as a byproduct of ore processing for lead, copper, tin and silver. Refining typically involves oxidation to bismuth oxide, followed by reduction to metal and purification.

Applications: Bismuth and its compounds have multiple uses. Bismuth subsalicylate is used in medicines for digestive problems. Bismuth oxide and bismuth oxychloride are used as pigments and cosmetic whiteners. Bi-based alloys, including low-melting solder alloys, are used in electronics and safety devices. Bi2Te3 is a widely used thermoelectric material for cooling and power generation. Bismuth compounds are also used in fireworks and glassmaking to produce colors.

Safety and isotopes: Bismuth compounds are generally considered of low toxicity compared with many heavy metals, but inhalation of dust and prolonged exposure should be avoided. Bi-209 is the only naturally occurring isotope and is radioactive with an extremely long half-life, making bismuth effectively the heaviest element with a long-lived natural isotope. The name derives from the German Wismut.