Tin

Category: post-transition metal Atomic number: 50 Colour: silvery white Melting point: 232°C (449°F) Boiling point: 2,602°C (4,716°F) First identified: ancient civilizations

Tin was a hugely important element in our history. It is a soft metal with a low melting point, which doesn’t corrode through oxidation. It was already in use about 10,000 years ago, but a key breakthrough came when metal workers worked out how to combine tin and copper to produce bronze in about 3500 BC. Metals had been smelted and extracted before this date, but this was the first significant alloy. It became clear that bronze combined the advantages of its two constituent metals – it was harder than tin, but melted at a lower temperature than copper, which made it easier to work with. Tin would also be alloyed with lead, copper and antimony as pewter, and used to ‘tin-plate’ ironware to stop it rusting.

The metal was a hugely important economic resource for the next few millennia, mined at various sites around the Mediterranean and in Cornwall, which may have been one of the motivations behind the Roman invasion of Britain. (The abbreviation ‘Sn’ comes from the Latin stannum.)

While it doesn’t oxidize, pure tin suffers from ‘tin pest’, a process by which it decays gradually into a grey, powdery dust. This starts happening at temperatures below 10°C but becomes much more severe at about 30°C below zero. It has been blamed for at least two historical disasters: during Napoleon’s failed Russian campaign in 1812 it is said that the buttons on his soldiers’ uniforms started to turn to dust in the cold winter, exacerbating their problems with hypothermia. And when Captain Scott and his companions set off back from the South Pole (having been beaten there by Amundsen), they returned to a store of tinned provisions but found that some paraffin had leaked through tiny holes in the tin – they all died of exposure subsequently.

‘Tin cans’ and ‘tin foil’ are actually made of aluminium (although they can be lined with tin), but many bells and organ pipes are still made of tin (usually alloyed with lead) and it is a significant ingredient in many alloys; for instance, those used for soldering (joining pieces of metal together). It is also used in glass production – the molten glass is floated on a bed of molten tin to create a flat surface. And many children continue to enjoy playing with tin toys (which are now mostly manufactured in China).