This is my fiftieth post and I have been mulling over what to make it about – it’s my half century celebration and I never thought I would have kept the blog going so long. So with all the talk this week of naming the new elements I thought I’d go back in time to element number 50 and boy has it been around for a while ! It’s TIN – named for the Etruscan God Tinia and its symbol Sn ( always a good quiz element ) from the Latin stannum.
One of my favourite books is ‘Napoleons Buttons – 17 molecules that changed history” by Penny le Couteur. Unfortunately I lent it out to a pupil in school and it wasn’t returned, and now it can only be bought on Amazon for an extortionate price ! It told the story of Napoleon’s retreat from Moscow and how in the depth of winter the buttons on his men’s uniforms started to fall off. Apparently they were made of tin and when the temperature dropped it changed from the allotrope shiny beta tin to brittle alpha tin (apparently the transition temperature is 13 oC but small amounts of antimony or bismuth can prevent this happening). This campaign was seen as the turning point in the Napoleonic wars and if the hypothermia suffered by Napoleon’s troops had been avoided would European history have played out differently ?
But tin goes back much further than the 1800’s and was known to ancient civilisations. Tin does not occur as a native element but can be isolated by heating it’s ore in the presence of carbon. Tin melts at a relatively low temperature (230 oC) so it has been used widely in alloys in particular bronze. Bronze is a mixture of about 80% copper and 20% tin ( the composition changes depending on the type of bronze required). The Bronze Age started about 3000 BC ( linking the Stone Age with the Iron Age) and the combination of stone and bronze allowed for tools and weapons to be made. The earliest tin-alloy bronzes date to 4000BC in Iran and Iraq and as copper and tin mines are not found together it involved a lot of trade to make bronze. Bronze is hardwearing and there is no superficial oxidation due to a barrier of copper oxide. However, it soon was superseded by iron as although not as durable it was more accessible. Nowadays bronze is the reserve of church bells and medals but once upon a time it defined an era.
So forget the tinfoil, tin soldiers and even the tin man -this element deserves its accolades, it’s time for tin to take its place as a defining element of the Periodic table, a history shaper and game changer.
thingsmychemistryteachersays 