Tin

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Tin

This is tin.

Symbol Sn
Atomic number 50
Atomic mass 118.69 amu

Tin, has been known since ancient times. The old testament cites tin as one of the known metals of the time (i.e. the others are gold, silver, copper, iron, and lead. In the 17th century, tin was quite popular for use in tools and utensil. Since the end of the Bronze Age, tin has been a plating medium for iron. A thin layer of tin prevents the oxidation that would otherwise corrode away iron objects.

Distinguishing properties

Pure tin is ductile and malleable. It can be rolled, spinned and extruded. It is silvery-white and looks much like aluminum, but feel more like lead.

Occurrence

Tin is found naturally in deposits of cassiterite as stannic oxide, SnO2. The largest deposits are in Malaysia which produces about one-third of the world's output. Bolivia, Thailand and Russia produce about 40%. Only a small amount is mined in Canada.

Usage

Tin is best known for its use in the manufacture of tin cans. It is most commonly seen as the outer layer on tin-plate or tin cans. It does not tarnish in the air, and protects iron only by excluding oxygen from the iron. This is in contrast to galvanizing where the protection by zinc is due to its higher activity than iron. Since tin is an expensive metal and tin is usually recovered from scrap tin-plate.

Tin is a popular alloying agent used in the manufacture of solders for electronic components. Soft solder is an alloy of lead and tin containing about 50-70% lead and 30-50% tin. Depending on the composition of the solder, it melts in the range of 183-250°C. Pure lead melts at 327°C and pure tin at 232°C.

Bronze that contains tin is very resistant to corrosion and is similarly used for castings, especially for marine propellers and other ship fittings. Bronze is also used for large statues and bells.

Common compounds

Other useful tin compounds include:

  • Tin(IV) oxide, SnO2, is sold as "putty powder" for polishing glass and metal.
  • Tin(IV) sulfide, SnS2, is also known as mosaic gold is used as a pigment.

See also

Periodic table of the elements