Tin
Symbol: Sn
Atomic Number: 50
Atomic Mass: 118.71 amu (atomic mass units)
Melting Point: 231.9 C (505.05 K, 449.41998 F)
Boiling Point: 2270.0 C (2543.15 K, 4118.0 F)
Number of Protons: 50
Number of Electrons: 50
Number of Neutrons: 69
Classification: Metallic
Crystal Structure: Tetragonal (white tin), cubic (grey tin)
Density @ 293 K: 7.31 grams per cubic centimeter
Color: white
Tin has been known from antiquity and archaeological evidence suggests that is has been used for over 5500 years. The symbol Sn derives from the Latin word for tin “stannum”. Tin is the Anglo-Saxon name of the element.
Tin exists in two temperature dependant allotropes. Grey tin is stable up to 13.2 C (286.35 K, 55.76 F) and white tin is stable above that temperature. The change from one allotrope to another was first notice on church organ pipes in some European cathedrals. The outgrowths of grey tin were thought to be the devils work. This change can be prevented by the addition of small amounts of bismuth or antimony .The metal is malleable and ductile with a highly organized crystalline structure. The breaking of its crystal structure when a bar of white tin is bent yields a noise known as the “tin cry”.
Tin has ten naturally occurring stable isotopes. The most common of these stable isotopes is tin-120 which makes up 32.58% of the total abundance on Earth. In addition nearly forty unstable isotopes of tin have been discovered.
The element has never been found free in nature. Tin is mainly obtained from the mineral ore cassiterite which is roasted with carbon to yield pure tin metal. Most of the world’s supply of tin comes from Malaysia, Bolivia, Indonesia, Zaire, Thailand, and Nigeria. The tin mines of Cornwall in the South West of England were once an important source of the metal but are now no longer productive.
Tin and its alloys have a long industrial heritage.
* Tin cans were very important in the preserving of foods. In fact the tin was a coating given to the inside and outside of steel cans to prevent corrosion. This type of cans has largely been replaced by aluminum and plastic containers.
* Alloyed with copper tin forms bronze.
* Alloyed with lead tin forms pewter and solders.
* Other useful tin alloys include type metal, fusible metal, bell metal and Babbitt metal.
The Pilkington process of glass production uses molten tin. The molten glass is layered onto the liquid tin and so forms a flat parallel layer. This is the main process used for window glass manufacture.
* Tin salts have been sprayed of to glass to produce electrically conductive coatings. These are used in lighting panels and frost free windshields.
* The tin compound stannous fluoride is used in some makes of toothpaste.
