gallium [Ga]
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Introduction
From the Latin gallia, an old name for France. Discovered spectroscopically & isolated by electrolysis in 1875 by French chemist Paul-Emile Lcoq de Boisbaudran.
Occurrence
- gallium-containing mineral are rare
- up to 1% gallium found in ores diaspore, sphalerite, germanite, & bauxite
- recovered as a by-product of burning coal
Characteristics
- blueish white-silvery metallic element
- hard & brittle at low temperatures
- extremely soft at room temperature; may be cut with a knife
- melts just above room temperature
- one of the few metals that can be liquid at room temperature
- one of the widest liquid ranges of any metal
- low vapor pressure even at high temperatures
- expands on freezing
- gallium salts generally of low toxicity
Uses
- gallium arsenide
- capable of converting electricity directly into coherent light
- component of light-emitting diodes (LED) & some integrating circuits
- semiconductors & solid-state devices
- microwaves
- low-melting alloys
- mirrors
- high-temperature thermometers
- radioactive gallium is used in medical imaging