Atomic number 50
Atomic mass 118.69 g.mol -1
Electronegativity according to Pauling 1.8
Density 5.77 g.cm-3 and 7.3 g.cm-3 at 20°C
Melting point 232 °C
Boiling point 2270 °C
Vanderwaals radius 0.162 nm
Ionic radius 0.112 nm (+2) ; 0.070 nm (+4)
Electronic shell [ Kr ] 4d10 5s25p2
Energy of first ionisation 708.4 kJ.mol -1
In its familiar compounds nickel is bivalent, although it assumes other valences. It also forms a number of complex compounds. Most nickel compounds are blue or green. Nickel dissolves slowly in dilute acids but, like iron, becomes passive when treated with nitric acid. Finely divided nickel adsorbs hydrogen.
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.
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.
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 superconducting magnets, tin oxide is used for ceramics and in gas sensors (as it absorbs a gas its electrical conductivity 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.