Tin (Sn)

Science / Periodic Table of Elements / Tin (Sn): Atomic number: 50, Atomic mass: 118.69 g.mol -1, Electronegativity: 1.8, Density: 5.77g.cm-3 (alpha) and 7.3 g.cm-3 at 20°C (beta), Melting point: 232 °C, Boiling point: 2270 °C, Vanderwaals radius: 0.162 nm, Ionic radius: 0.112 nm (+2) ; 0.070 nm (+4), Isotopes: 20, Electronic shell: [ Kr ] 4d10 5s25p2, Energy of first ionisation: 708.4 kJ.mol -1, Energy of second ionisation: 1411.4 kJ.mol -1, Energy of third ionisation: 2942.2 kJ.mol -1, Energy of fourth ionisation: 3929.3 kJ.mol -1, Discovered by: The ancients. Tin is a soft, pliable, silvery-white metal. Tin is not easily oxidized and resists corrosion because it is protected by an oxide film. Tin resists corrosion from distilled sea and soft tap water, and can be attacked by strong acids, alkalis and acid salts. Applications: Tin is used in for can coating: tin-plated steel containers are widely used for food preservation. Tin alloys are employed in many ways: as solder for joining pipes or electric circuits, pewter, bell metal, babbit metal and dental amalgams. The niobium-tin alloy is used for superconductiong magnets, tin oxide is used for ceramics and in gas sensors (as it absorbs a gas its electrical conmductivity increases and this can be monitored). Tin foil was once a common wrapping material for foods and drugs, now replaced by the use of aluminium foil. Tin in the environment: Tin oxide is insoluble and the ore strongly resists weathering, so the amount of tin in soils and natural waters is low. The concentration in soils is generally between the range 1-4 ppm but some soils have less that 0.1 ppm while peats can have as much 300 ppm. There are few tin-containing minerals, but only one is of commercial significance and that is cassiterite. The main mining area to be found in the tin belt which goes from China through Thailand, Brima and Malaysia to the islands of Indonesia. Malaysia produces 40% of the world's tin. Other important tin mining area are Bolivia and Brazil. Global production is in excess of 140.000 tonnes per year and workable reserves amount to more 4 million tonnes. Tin concetrates are produces in around 130.000 tonnes per year.

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