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Bismuth

Bismuthis a white crystalline metal with a pinkish tinge belonging to group 15 (formerly VB) of the periodic table; a.n. is 83; r.a.m. is 208.98; relative density (r.d.) is 9.78; m.p. is 271.3°C; b.p. is 1560°C. The most important ores are bismuthinite (Bi₂S₃) and bismite (Bi₂O₃). Peru, Japan, Mexico, Bolivia and Canada are major producers. The metal is extracted by carbon reduction of its oxide. Bismuth is the most diamagnetic of all metals and its thermal conductivity is lower than the thermal conductivity of any metal except mercury. The metal has a high electrical resistance and a high Hall effect when placed in magnetic fields. It is used to make low-melting-point casting alloys with tin and cadmium. These alloys expand on solidification to give clear replication of intricate features. It is also used to make thermally activated safety devices for fire-detection and sprinkler systems. More recent applications include its use as a catalyst for making acrylic fibres, as a constituent of malleable iron, as a carrier of uranium-235 fuel in nuclear reactors and as a specialized thermocouple material. Bismuth compounds (when lead-free) are used for cosmetics and medical preparations. It is attacked by oxidizing acids, steam (at high temperatures) and by moist halogens. It burns in air with a blue flame to produce yellow oxide fumes. C. G. Junine first demonstrated that it was different from lead in 1753.

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