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 |
Gallium |
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Pronunciation | (GAL-ee-əm) |
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Appearance | silver-white |
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Standard atomic weight Ar, std(Ga) | 7001697230000000000♠69.723(1)[1] |
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Mass number | Ga: |
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Gallium in the periodic cairt |
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Atomic nummer (Z) | 31 |
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Group | group 13 (boron group) |
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Period | period 4 |
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Block | p-block |
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Element category | Post-transeetion metal |
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Electron confeeguration | [Ar] 3d10 4s2 4p1 |
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Electrons per shell | 2, 8, 18, 3 |
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Pheesical properties |
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Phase at STP | solit |
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Meltin pynt | 302.9146 K (29.7646 °C, 85.5763 °F) |
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Bylin pynt | 2477 K (2204 °C, 3999 °F) |
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Density (near r.t.) | 5.91 g/cm3 |
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when liquid (at m.p.) | 6.095 g/cm3 |
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Heat o fusion | 5.59 kJ/mol |
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Heat o vapourisation | 254 kJ/mol |
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Molar heat capacity | 25.86 J/(mol·K) |
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Vapour pressur
P (Pa)
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1
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10
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100
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1 k
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10 k
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100 k
|
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at T (K)
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1310
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1448
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1620
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1838
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2125
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2518
|
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Atomic properties |
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Oxidation states | −5, −4, −3,[2] −2, −1, +1, +2, +3[3] (an amphoteric oxide) |
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Electronegativity | Pauling scale: 1.81 |
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Ionisation energies | |
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Atomic radius | empirical: 135 pm |
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Covalent radius | 122±3 pm |
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Van der Waals radius | 187 pm |
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Spectral lines o gallium |
Ither properties |
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Naitural occurrence | Ga: Primordial |
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Creestal structur | orthorhombic |
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Speed o soond thin rod | 2740 m/s (at 20 °C) |
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Thermal expansion | 18 µm/(m·K) (at 25 °C) |
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Thermal conductivity | 40.6 W/(m·K) |
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Electrical resistivity | 270 n Ω·m (at 20 °C) |
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Magnetic orderin | diamagnetic |
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Young's modulus | 9.8 GPa |
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Poisson ratio | 0.47 |
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Mohs haurdness | 1.5 |
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Brinell haurdness | 60 MPa |
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CAS Nummer | 7440-55-3 |
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History |
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Prediction | Dmitri Mendeleev (1871) |
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Diskivery | Lecoq de Boisbaudran (1875) |
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First isolation | Lecoq de Boisbaudran (1875) |
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Main isotopes o gallium |
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| references |