| Gallium - Ga
CAS: 7440-55-3 Description: Soft, silver-white metal, similar to aluminum Classification: Other Metals Date of Discovery: 1875 Discoverer: Paul Emile Lecoq de Boisbaudran Name Origin: Latin Gallia, "France"; also Latin gallus, "a cock" (Fr. le coq) |
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Atomic Number: 31
Number of Neutrons: 39 Atomic Mass: 69.723(1) amu Melting Point: 29.7646 °C Boiling Point: 2204 °C Density (29.6 °C): 5.904 g/cm3 (solid) 6.095 g/cm3 (liquid) Atomic volume: 11.8 cm3/mol Electrical resistivity: 0.0678 10-6/cm 
Thermal conductivity: 0.406 W/cmK Enthalpy of atomization: 276.14 kJ/mol Enthalpy of vaporization: 258.70 kJ/mol Enthalpy of fusion: 5.590 kJ/mol Specific heat capacity: 0.37 J/gK |
Energy levels: 2-8-18-3
Electron configuration: [Ar]3d104s24p1 Crystal Structure: Orthorhombic Atomic radius: 1.81 Å Covalent radius: 1.26 Å Oxidation States: +2, +3 Electronegativity, Pauling: 1.81 Electron affinity: 0.3 eV First ionization energy: 5.999 eV 2nd ionization energy: 20.51 eV 3rd ionization energy: 30.71 eV Polarizability: 8.12 10-24cm3 |
| Isotope | Natural Abundance | Atomic Mass | Half-life | Decay Mode | Spin |
| 61Ga | 60.9492 | 0.15 s |  + |
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| 62Ga | 61.94418 | 0.116 s | +; EC |
0+ | |
| 63Ga | 62.9391 | 32 s | +; EC |
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| 64Ga | 63.936838 | 2.63 m | + |
0+ | |
| 65Ga | 64.9394 | 15.2 m | +; EC |
3/2- | |
| 66Ga | 65.931592 | 9.5 h | +; EC |
0+ | |
| 67Ga | 66.928205 | 3.260 d | EC | 3/2- | |
| 68Ga | 67.927983 | 1.130 h | +; EC |
1+ | |
| 69Ga | 60.108(6) | 68.925581 | Stable | 3/2- | |
| 70Ga | 69.926027 | 21.1 m | EC; - |
1+ | |
| 71Ga | 39.892(6) | 70.924707 | Stable | 3/2- | |
| 72Ga | 71.96372 | 14.10 h | - |
3- | |
| 73Ga | 72.92517 | 74.87 h | - |
3/2- | |
| 74mGa | 10 s | IT | 1+ | ||
| 74Ga | 73.92694 | 8.1 m | - |
3- | |
| 75Ga | 74.92650 | 2.10 m | - |
3/2- | |
| 76Ga | 75.9289 | 29 s | - |
3- | |
| 77Ga | 76.9293 | 13.0 s | - |
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| 78Ga | 77.9317 | 5.09 s | - |
3+ | |
| 79Ga | 78.9329 | 2.85 s | - |
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| 80Ga | 79.9366 | 1.68 s | - |
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| 81Ga | 80.9377 | 1.22 s | - |
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| 82Ga | 81.9432 | 0.599 s | - |
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| 83Ga | 82.9469 | 0.308 s | - |
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| 84Ga | 83.952 | - |
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Predicted and described by Mendeleev as ekaaluminum, and discovered spectroscopically by Lecoq de Boisbaudran in 1875, who in the same year obtained the free metal by electrolysis of a solution of the hydroxide in KOH. Gallium is often found as a trace element in diaspore, sphalerite, germanite, bauxite, and coal. Some flue dusts from burning coal have been shown to contain as much 1.5% gallium. It is the only metal,
except for mercury, cesium, and rubidium, which can be liquid near room temperatures; this makes possible its use in high-temperature thermometers. It has one of the longest liquid ranges of any metal and has a low vapor pressure even at high temperatures. There is a strong tendency for gallium to supercool below its freezing point. Therefore, seeding may be necessary to initiate solidification. Ultra-pure gallium has a beautiful, silvery appearance, and the solid metal exhibits a conchoidal fracture similar to glass. The metal expands 3.1% on solidifying; therefore, it should not be stored in glass or metal containers, as they may break as the metal solidifies. Gallium wets glass or porcelain and forms a brilliant mirror when it is painted on glass. It is widely used in doping semiconductors and producing solid-state devices such as transistors. High-purity gallium is attacked only slowly by mineral acids. Magnesium gallate containing divalent impurities such as Mn+2 is finding use in commercial ultraviolet activiated powder phosphors. Gallium arsenide is capable of converting electricity directly into coherent light. Gallium readily alloys with most metals, and has been used as a component in low-melting alloys. Its toxicity appears to be of a low order, but should be handled with care until more data are forthcoming. Natural gallium contains two stable isotopes. Twenty-three other isotopes, one of which is an isomer, are known. The metal can be supplied in ultrapure form (99.99999+%).
LINKS: Gallium Arsenide Crystal Growth in Microgravity Gallium in Weapons-Grade Plutonium Gallium scan GaAsNET Industry Resource on Gallium Arsenide Electronics Is Gallium a 21st Century Essential Human Nutrient? USGS Minerals Information: Gallium Return
Sources for the information on this website include: Lide, David R., ed. CRC Handbook of Chemistry and Physics, 78th Ed., 1997-1998. |
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