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Oxidation & Electrons | Appearance & Characteristics Reactions | Compounds | Radius | Conductivity Abundance & Isotopes 
Crytals of gallium metal. (Photo: Foobar, GNU Free Documentation License). |
General:
| Name: Gallium | Symbol: Ga |
| Type: Metal | Atomic weight: 69.723 |
| Density @ 293 K: 5.907 g/cm3 | Atomic volume: 11.8 cm3/mol |
| Discovered: Gallium was discovered by Paul E. Lecoq de Boisbaudran through a spectroscope in 1875. Its now characteristic spectrum (two violet lines) identified it as a new element. De Boisbaudran later isolated gallium by electrolysis of its hydroxide in potassium hydroxide solution. The origin of the name comes from the Latin word 'Gallia', meaning France. | |
States
| State (s, l, g): solid | |
| Melting point: 302.91 K (29.76 oC) | Boiling point: 2673 K (2200 oC) |
Energies
| Specific heat capacity: 0.37 J g-1 K-1 | Heat of atomization: 277 kJ mol-1 |
| Heat of fusion: 5.590 kJ mol-1 | Heat of vaporization : 258.70 kJ mol-1 |
| 1st ionization energy: 578.8 kJ mol-1 | 2nd ionization energy: 1979.3 kJ mol-1 |
| 3rd ionization energy: 2963 kJ mol-1 | Electron affinity: 41 kJ mol-1 |
Oxidation & Electrons
| Shells: 2,8,18,3 | Electron configuration: [Ar] 3d10 4s2 4p1 |
| Minimum oxidation number: 0 | Maximum oxidation number: 3 |
| Min. common oxidation no.: 0 | Max. common oxidation no.: 3 |
| Electronegativity (Pauling Scale): 1.81 | Polarizability volume: 8.1 Å3 |
Appearance & Characteristics
| Structure: orthorhombic | Color: silvery-blue |
| Hardness: 1.5 mohs | |
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Harmful effects: Gallium is considered to be non-toxic. Characteristics: Gallium is a silvery, glass-like, soft metal. It sits close to the non-metals in the periodic table and its metallic properties aren't as obviously metallic as most other metals. Solid gallium is brittle and is a poorer electrical conductor than lead. The solid metal fractures conchoidally. (Conchoidally means like a shell - the fractured surfaces are curved like a sea shell.) Gallium has the largest liquid range of any element and is one of the few metals that is liquid near room temperature (m.pt. 29.76 oC, 85.6 oF ), melting in the hand. The other metals with this property are cesium, francium and mercury. Bromine is the only non-metallic element that is liquid at or around room-temperature. Gallium liquid clings to or wets glass and similar surfaces. Gallium also has the unusual property that (like water) it expands as it freezes. Four other elements expand when they freeze; silicon, bismuth, antimony and germanium Uses: Low melting gallium alloys are used in some medical thermometers as non-toxic substitutes for mercury. Gallium arsenide is used in semiconductor production mainly for laser diodes, light-emitting diodes and solar panels. It is also used to create brilliant mirrors. |
Reactions
| Reaction with air: mild, ⇒ Ga2O3 | Reaction with 6 M HCl: mild, ⇒ H2, GaCl3 |
| Reaction with 15 M HNO3: | Reaction with 6 M NaOH: mild, ⇒ H2, [Ga(OH4)]2- |
Compounds
| Oxide(s): Ga2O3 | Chloride(s): GaCl, Ga2Cl6 |
| Hydride(s): GaH3 |
Radius
| Atomic radius: 135 pm | Ionic radius (1+ ion): pm |
| Ionic radius (2+ ion): pm | Ionic radius (3+ ion): 76 pm |
| Ionic radius (2- ion): pm | Ionic radius (1- ion): pm |
Conductivity
| Thermal conductivity: 40.6 W m-1 K-1 | Electrical conductivity: 1.8 x 10-6 S m-1 |
Abundance & Isotopes
| Abundance earth's crust: 19 parts per million by weight, 5.5 parts per million by moles | |
| Abundance solar system: 40 parts per billion by weight, 0.6 parts per billion by moles | |
| Cost, pure: $220 per 100g | |
| Cost, bulk: $ per 100g | |
| Source: Gallium does not exist free in nature and there are no minerals with any substantial gallium content. Commercially, most gallium is extracted as a byproduct of aluminum and zinc production. Gallium is also extracted from the flue dusts of coal. | |
| Isotopes: Gallium has 24 isotopes whose half-lives are known, with mass numbers 61 to 84. Of these, two are stable: 69Ga and 71Ga with natural abundances of 60.1% and 39.9% respectively. | |
