| Gallium |
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| Atomic Number - | 31 | Melting Point (°C,°F) - | 29.7646 °C, 85.5763 °F |
| Atomic Symbol - | Ga | Boiling Point (°C,°F) - | 2204 °C, 3999 °F |
| Atomic Mass - | 69.72 | Electron Configuration - | [Ar] 3d10 4s2 4p1 |
| Group - | 13 | Electrons Per Shell - | 2, 8, 18, 3 |
| Period - | 4 | Protons - | 31 |
| Series - | Poor Metals | Neutrons - | 39 |
| Block - | p-block | | |
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Element Description - Gallium is a chemical element in the periodic table that has the symbol Ga and atomic number 31. A rare, soft silvery metallic poor metal, gallium is a brittle solid at low temperatures but liquefies slightly above room temperature and indeed will melt in the hand. It occurs in trace amounts in bauxite and zinc ores. An important application is in the compound gallium arsenide, used as a semiconductor, most notably in light-emitting diodes (LEDs). |
Element Characteristics - Very pure gallium has a stunning silvery color and its solid metal fractures conchoidally like glass. Gallium metal expands by 3.1 percent when it solidifies, and therefore should not be stored in either glass or metal containers, as they may break as the metal solidifies. Gallium also corrodes most other metals by diffusing into their metal lattice.
Gallium is one of the metals (with caesium and mercury) which are liquid at or near normal room temperature, and can therefore be used in metal-in-glass thermometers. It is also notable for having one of the largest liquid ranges for a metal, and (unlike mercury) for having a low vapor pressure at high temperatures.
This metal has a strong tendency to supercool below its melting point, thus necessitating seeding in order to solidify. High-purity gallium is attacked slowly by mineral acids. The melting point temperature is very low, T = 30 °C, and the density is higher in the liquid state than in the crystalline state (like water, but unlike most materials).
Gallium does not crystallize in any of the simple crystal structures. The stable phase under normal conditions is orthorhombic with 8 atoms in the conventional unit cell. Each atom has only one nearest neighbor (at a distance of 244 pm) and six other neighbors within additional 39 pm. Many stable and metastable phases are found as function of temperature and pressure.
The bonding between the nearest neighbors is found to be of covalent character, hence Ga2 dimers are seen as the fundamental building blocks of the crystal. The compound with arsenic, gallium arsenide is a semiconductor commonly used in light-emitting diodes. |
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