tin (Sn)

Cassiterite. Credit: Mineral Information Institute

A malleable, fairly soft, silvery-white, metallic element in group IVA of the periodic table; it occurs mainly as cassiterite (tin dioxide, TnO₂), from which it is obtained by smelting with coal. Tin exhibits allotropy: white (β) tin, the normal form, changes below 13.2°C to gray (α) tin, a powdery metalloid form resembling germanium, and known as "in pest."

Tin is unreactive, but dissolves in concentrated acids and alkalis, and is attacked by halogens. It is used to coat other metals to prevent corrosion, and forms part of numerous alloys, such as soft solder, pewter, type metal, and bronze.

atomic number	50
relative atomic mass	118.69
relative density	7.31
melting point	231.9°C (449.4°F)
boiling point	2,507°C (4,545°F)

Compounds of tin

Tin forms organotin compounds, used in biocides, and also inorganic compounds: tin (II) and tin (IV) salts. Tin (IV) oxide (SnO₂) is a white powder (sublimes at 1,800°C) prepared by calcining cassiterite or burning finely divided tin; it is used in glazes and as an abrasive. Tin (II) chloride (SnCl₂) is a white crystalline solid, prepared by dissolving tin in hydrochloric acid and used as a reducing agent, in tin-plating, and as a mordant. Melting point 246°C, boiling point 652°C.

Related category

• INORGANIC CHEMISTRY

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