Gallium
| Atomic Number: | 31 |
| Symbol: | Ga |
| Atomic Weight: | 69.735 |
| Discovery: | Boisbaudran 1875 |
| Electron Configuration: | [Ar]4s23d104p1 |
| Word Origin: | Latin Gallia, France and gallus, a translation of Lecoq, a cock (name of its discoverer was Lecoq de Boisbaudran) |
| Isotopes: | Two isotopes of gallium are known. Gallium-69 accounts for 60.108% of the natural abundance of the element. Gallium-71 accounts for 39.892% of the element's natural abundance. |
| Properties: | Gallium has a melting point of 29.78°C, boiling point of 2403°C, specific gravity of 5.904 (29.6°C), specific gravity of 6.095 (29.8°C, liguid), with a valence of 2 or 3. Gallium has one of the longest liquid temperature ranges of any metal, with a low vapor pressure even at high temperatures. The element has a strong tendency to supercool below its freezing point. Seeding is sometimes necessary to initiate solidification. Pure gallium metal has a silvery appearance. It exhibits a conchoidal fracture that it similar to a glass fracture in appearance. Gallium expands 3.1% on solidifying, so it should not be stored in a metal or glass container that can break upon its solidification. Gallium wets glass and porcelain, forming a brilliant mirror finish on glass. Highly pure gallium is only slowly attacked by mineral acids. Gallium is associated with a relatively low toxicity, but should be handled with care until more health data has been accumulated. |
| Uses: | Since it is a liquid near room temperature, gallium is used for high-temperature thermometers. Gallium is used to dope semiconductors and for producing solid-state devices. Gallium arsenide is used to convert electricity into coherent light. Magnesium gallate with divalent impurities (e.g., Mn2+) is used to make commercial ultraviolet-activated powder phosphors. |
| Sources: | Gallium may be found as a trace element in sphalerite, diaspore, bauxite, coal, and germanite. Flue dusts from burning coal may contain as much as 1.5% gallium. The free metal may be obtained by electrolysis of its hydroxide in a KOH solution. |
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