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Zinc - Gallium - Germanium
Name, Symbol, NumberGallium, Ga, 31
Chemical series True metals[?]
Group, Period, Block13 (IIIA)[?], 4 , p
Density, Hardness 5904 kg/m3, 1.5
Appearance silvery white
Atomic Properties
Atomic weight 69.723 amu
Atomic radius (calc.) 130 (136)pm
Covalent radius 126 pm
van der Waals radius 187 pm
Electron configuration [Ar]3d10 4s2 4p1
e- 's per energy level2, 8, 18, 3
Oxidation states (Oxide) 3 (amphoteric)
Crystal structure Orthorhombic
Physical Properties
State of matter Orthorhombic
Melting point 302.91 K (85.57 F)
Boiling point 2477 K (3999 F)
Molar volume 11.80 ×10-3 m3/mol
Heat of vaporization 258.7 kJ/mol
Heat of fusion 5.59 kJ/mol
Vapor pressure 9.31 E-36 Pa at 302.9 K
Speed of sound 2740 m/s at 293.15 K
Electronegativity 1.81 (Pauling scale)
Specific heat capacity 370 J/(kg*K)
Electrical conductivity 6.78 106/m ohm
Thermal conductivity 40.6 W/(m*K)
1st ionization potential 578.8 kJ/mol
2nd ionization potential 1979.3 kJ/mol
3rd ionization potential 2963 kJ/mol
4th ionization potential 6180 kJ/mol
Most Stable Isotopes
isoNAhalf-life DMDE MeVDP
69Ga60.1%Ga is stable with 38 neutrons
71Ga39.9%Ga is stable with 39 neutrons
SI units & STP are used except where noted.
Gallium is a chemical element in the periodic table that has the symbol Ga and atomic number 31. A rare, soft silvery metallic true metal[?], gallium is brittle at low temperatures but is liquid above room temperature and occurs in trace amounts in bauxite and zinc ores. Gallium arsenide is used as a semiconductor, most notably in light-emitting diodes (LEDs).

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Notable Characteristics Very-pure gallium has a stunning silvery color and its solid metal fractures conchoidaly[?] like glass. Gallium metal expands 3.1 percent when it solidifys and therefore shouldn't be stored in either glass or metal containers. Gallium also corrodes most other metals by diffusing into their metal lattice.

Gallium is one of four metals (with cesium, mercury, and rubidium) which are liquid at near normal room temperature and can therefore be used in high-temperature thermometers. It is also notable for having one of the largest liquid ranges for a metal and for having a low vapor pressure at high temperatures.

This metal has a strong tendency 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 in the case of water; the opposite effect is normally found for metals).

Ga 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 2.44 Å) and six other neighbors within additional 0.39 Å. 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 is seen as the fundamental building block of the crystal. The compound, gallium arsenide can convert electricity directly into coherent light (this property is vital to light-emitting diodes). Applications Analog integrated circuits are the largest application for gallium, with optoelectronic devices (mostly laser diodes and light-emitting diodes) as the second largest end use. Other uses;

  • Since it wets glass or porcelain, gallium is used to create brilliant mirrors.
  • Used widely to dope semiconductors and produce solid-state devices like transistors.
  • Gallium readily alloys with most metals, and has been used as a component in low-melting alloys.
Magnesium gallate containing impurities (such as Mn+2), is beginning to be used in ultraviolet-activated phosphor powder. History Gallium (Latin Gallia meaning "France"; also gallus, meaning "cock") was discovered spectroscopically by Lecoq de Boisbaudran[?] in 1875 by its characteristic spectrum (two violet lines) in an examination of a zinc blende from the Pyrenees. Before its discovery, most of its properties had been predicted and described by Dmitri Mendeleev (whom called the hypothetical element eka-aluminum) on the basis of the periodic law[?]. Later in 1875, Boisbaudran obtained the free metal through the electrolysis hydroxide in KOH solution. He named the element after his native land of France and, in one of those multilingual puns so beloved of men of science of the early 19th century, after himself, as 'Lecoq' = the rooster, and Latin for rooster is "gallus". Occurrence This true metal is oftentimes found as a trace component in bauxite, coal, diaspore[?], germanite, and sphalerite. Some flue dusts from burning coal have been shown to contain as much 1.5 percent gallium.

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