Gallium

Gallium is a chemical element wi seembol Ga an atomic nummer 31. Elemental gallium disnae occur in free furm in naitur, but as the gallium(III) compoonds that is in trace amoonts in zinc ores an in bauxite. Gallium is a saft sillery metal, an elemental gallium is a brickle solit at law temperaturs. Gif it is held in the human haund lang eneuch, gallium will melt, syne it melts at the temperatur o aboot 29.76 °C (85.57 °F) (slichtly abuin ruim temperatur). The meltin pynt o gallium is uised as a temperatur reference pynt. The alloy galinstan (68.5% gallium, 21.5% indium, an 10% tin) haes the even lawer meltin pynt o −19 °C (−2 °F), weel ablo the freezin pynt o watter. Beginnin wi its discovery in 1875 throu the era o semiconductors, gallium wis uised primarily as an agent tae mak alloys that melt at law temperaturs. Then, gallium became uiseful in semiconductors, includin as a dopant.

Gallium,  ₃₁Ga

General properties
Appearance	silver-white
Staundart atomic wecht (Ar, staundart)	7001697230000000000♠69.723(1)
Gallium in the periodic cairt
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 Airn Cobalt Nickel Capper Zinc Gallium Germanium Arsenic Selenium Bromine Krypton Rubidium Strontium Yttrium Zirconium Niobium Molybdenum Technetium Ruthenium Rhodium Palladium Siller (element) 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 Gowd Mercur (element) Thallium Leid (element) 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 Ununtrium Flerovium Ununpentium Livermorium Ununseptium Ununoctium Al ↑ Ga ↓ In zinc ← gallium → germanium
Atomic nummer (Z)	31
Group	group 13 (boron group)
Period	period 4
Element category	post-transition metal
Block	p-block
Electron confeeguration	[Ar] 4s2 3d10 4p1
Electrons per shell	2, 8, 18, 3
Pheesical properties
Phase (at STP)	solit
Meltin pynt	302.9146 K ​(29.7646 °C, ​85.5763 °F)
Bylin pynt	2477 K ​(2204 °C, ​3999 °F)
Density (near r.t.)	5.91 g/cm3
when liquid (at m.p.)	6.095 g/cm3
Heat o fusion	5.59 kJ/mol
Heat o vapourisation	254 kJ/mol
Molar heat capacity	25.86 J/(mol·K)
Vapour pressur 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 ​amphoteric oxide
Electronegativity	Pauling scale: 1.81
Ionisation energies	(more)
Atomic radius	empirical: 135 pm
Covalent radius	122±3 pm
Van der Waals radius	187 pm
Spectral lines o Gallium
Miscellanea
Creestal structur	​orthorhombic
Speed o soond 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 n Ω·m (at 20 °C)
Magnetic orderin	diamagnetic
Young's modulus	9.8 GPa
Poisson ratio	0.47
Mohs haurdness	1.5
Brinell haurdness	60 MPa
CAS Nummer	7440-55-3
History
Predeection	Dmitri Mendeleev (1871)
Diskivery	Lecoq de Boisbaudran (1875)
First isolation	Lecoq de Boisbaudran (1875)
Main isotopes o gallium
Iso­tope Abun­dance Hauf-life (t1/2) Decay mode Pro­duct 69Ga 60.11% stable 71Ga 39.89% stable