Gallium salt

Gallium,  ₃₁Ga

General properties
Pronunciation	/ˈɡæliəm/ ​(GAL-ee-əm)
Appearance	silvery blue
Standard atomic weight (Ar, standard)	7001697230000000000♠69.723(1)
Gallium in the periodic table
Hydrogen Helium Lithium Beryllium Boron Carbon Nitrogen Oxygen Fluorine Neon Sodium Magnesium Aluminium Silicon Phosphorus Sulfur Chlorine Argon Potassium Calcium Scandium Titanium Vanadium Chromium Manganese Iron Cobalt Nickel Copper Zinc Gallium Germanium Arsenic Selenium Bromine Krypton Rubidium Strontium Yttrium Zirconium Niobium Molybdenum Technetium Ruthenium Rhodium Palladium Silver Cadmium Indium Tin Antimony Tellurium Iodine Xenon Caesium Barium Lanthanum Cerium Praseodymium Neodymium Promethium Samarium Europium Gadolinium Terbium Dysprosium Holmium Erbium Thulium Ytterbium Lutetium Hafnium Tantalum Tungsten Rhenium Osmium Iridium Platinum Gold Mercury (element) Thallium Lead Bismuth Polonium Astatine Radon Francium Radium Actinium Thorium Protactinium Uranium Neptunium Plutonium Americium Curium Berkelium Californium Einsteinium Fermium Mendelevium Nobelium Lawrencium Rutherfordium Dubnium Seaborgium Bohrium Hassium Meitnerium Darmstadtium Roentgenium Copernicium Nihonium Flerovium Moscovium Livermorium Tennessine Oganesson Al ↑ Ga ↓ In zinc ← gallium → germanium
Atomic number (Z)	31
Group	group 13 (boron group)
Period	period 4
Element category	post-transition metal
Block	p-block
Electron configuration	[Ar] 3d10 4s2 4p1
Electrons per shell	2, 8, 18, 3
Physical properties
Phase at STP	solid
Melting point	302.9146 K ​(29.7646 °C, ​85.5763 °F)
Boiling point	2673 K ​(2400 °C, ​4352 °F)
Density (near r.t.)	5.91 g/cm3
when liquid (at m.p.)	6.095 g/cm3
Heat of fusion	5.59 kJ/mol
Heat of vaporization	256 kJ/mol
Molar heat capacity	25.86 J/(mol·K)
Vapor pressure P (Pa) 1 10 100 1 k 10 k 100 k at T (K) 1310 1448 1620 1838 2125 2518
Atomic properties
Oxidation states	3, 2, 1, −1, −2, −4, −5​(an amphoteric oxide)
Electronegativity	Pauling scale: 1.81
Ionization energies	1st: 578.8 kJ/mol 2nd: 1979.3 kJ/mol 3rd: 2963 kJ/mol (more)
Atomic radius	empirical: 135 pm
Covalent radius	122±3 pm
Van der Waals radius	187 pm
Spectral lines
Miscellanea
Crystal structure	​orthorhombic
Speed of sound thin rod	2740 m/s (at 20 °C)
Thermal expansion	18 µm/(m·K) (at 25 °C)
Thermal conductivity	40.6 W/(m·K)
Electrical resistivity	270 nΩ·m (at 20 °C)
Magnetic ordering	diamagnetic
Magnetic susceptibility	−21.6·10−6 cm3/mol (at 290 K)
Young's modulus	9.8 GPa
Poisson ratio	0.47
Mohs hardness	1.5
Brinell hardness	56.8–68.7 MPa
CAS Number	7440-55-3
History
Naming	after Gallia (Latin for: France), homeland of the discoverer
Prediction	Dmitri Mendeleev (1871)
Discovery and first isolation	Lecoq de Boisbaudran (1875)
Main isotopes of gallium
Iso­tope Abun­dance Half-life (t1/2) Decay mode Pro­duct 66Ga syn 9.5 h β+ 66Zn 67Ga syn 3.3 d ε 67Zn 68Ga syn 1.2 h β+ 68Zn 69Ga 60.11% stable 70Ga syn 21 min β− 70Ge ε 70Zn 71Ga 39.89% stable 72Ga syn 14.1 h β− 72Ge 73Ga syn 4.9 h β− 73Ge
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Gallium is a chemical element with symbol Ga and atomic number 31. It is in group 13 of the periodic table, and thus has similarities to the other metals of the group, aluminium, indium, and thallium. Gallium does not occur as a free element in nature, but as gallium(III) compounds in trace amounts in zinc ores and in bauxite. Elemental gallium is a soft, silvery blue metal at standard temperature and pressure, a brittle solid at low temperatures, and a liquid at temperatures greater than 29.76 °C (85.57 °F) (above room temperature, but below the normal human body temperature).

The melting point of gallium is used as a temperature reference point. Gallium alloys are used in thermometers as a non-toxic and environmentally friendly alternative to mercury, and can withstand higher temperatures than mercury. The alloy galinstan (68.5% gallium, 21.5% indium, and 10% tin) has an even lower melting point of −19 °C (−2 °F), well below the freezing point of water.

Since its discovery in 1875, gallium has been used to make alloys with low melting points. It is also used in semiconductors as a dopant in semiconductor substrates.

Gallium is predominantly used in electronics. Gallium arsenide, the primary chemical compound of gallium in electronics, is used in microwave circuits, high-speed switching circuits, and infrared circuits. Semiconducting gallium nitride and indium gallium nitride produce blue and violet light-emitting diodes (LEDs) and diode lasers. Gallium is also used in the production of artificial gadolinium gallium garnet for jewelry.