Tin

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MELTING POINT: 231.9°C
BOILING POINT: 2,270.0°C
DENSITY: 7.31 g/cm ³
MOST COMMON IONS: Sn ²⁺ , Sn ⁴⁺

Tin makes up only about 0.001 percent of the earth's crust, but it was well known in the ancient world. Named after the Etruscan god Tinia, tin has the symbol Sn, which comes from the Latin word for tin, stannum, which is related to the word stagnum (dripping), because tin melts easily. Tin is primarily obtained from the mineral cassiterite (SnO ₂ ) and is extracted by roasting cassiterite in a furnace with carbon.

Tin is a soft, pliable metal , but it is not used as such, because below 13°C, it slowly changes to a different allotype and forms a powder. Steel is plated with tin to make cans for food, and tin is also used in solders. Some tin compounds have been employed as antifouling agents in paint for ships and boats to prevent barnacles. However, even at low concentrations, these compounds are deadly to marine life, especially to oysters. Tin is thought to be an essential element for some living things, and this may also be true for humans.

A major use of tin has been as a constituent of alloys —such as bronze (tin and copper); pewter (tin and lead); superconducting wire (tin and niobium); Babbitt metal (tin, copper, and antimony); Bell metal (tin and copper); and fusible metal (tin, bismuth, and lead).

Stannous fluoride (SnF ₂ ), a compound of tin and fluorine, is used in some toothpastes to decrease the incidence of caries.

George H. Wahl Jr.

Bibliography

Internet Resources

ChemGlobe. Available from http://www.vcs.ethz.ch/chemglobe/ptoe/_/50.html .

Jefferson Lab. "It's Elemental: The Element Tin." Available from http://education.jlab.org/itselemental/ele050.html .

Royal Society of Chemistry. "Visual Elements: Tin." Available from http://www.chemsoc.org/viselements/pages/tin.html .