* Gallium is a member of the main group metals family:
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GALLIUM / Ga / 31
A soft, silvery-white metal, with a melting point so low that it
will melt when held in the hand, and with moderate resistance to
corrosion. Along with the low melting point, it is also unusual in
that it expands when it solidifies. Two isotopes, both stable, are
found in nature: Ga<69/31> (60%) and Ga<71/31> (40%).
atomic weight: 69.723
abundance: 34th
density: 6.1 gm/cc (liquid), 5.9 gm/cc (solid)
melting point: 30 C
boiling point: 2,403 C
valence: 2 3
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Although gallium is more common than lead in the Earth's crust, gallium is widely dispersed in various chemical compounds -- it doesn't form ores -- and is obtained as a by-product of the refining of other metals, particularly the refining of bauxite into aluminum. World production is only a few tens of tonnes a year. It is prominently used in electronic devices, in the form of compounds such as gallium arsenide (GaAs). Light-emitting diodes (LEDs) and semiconductor lasers are often made of gallium-based compounds.
