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Gallium (Ga)

Gallium is a chemical element of the periodic table with chemical symbol Ga and atomic number 31 with an atomic weight of 69.7231 u and is classed as post-transition metal and is part of group 13 (boron group). Gallium is solid at room temperature.

Gallium in the periodic table

Atomic number31
Group13 (Boron group)
ClassificationPost-Transition Metal
Color Silver
Number of protons31 p+
Number of neutrons39 n0
Number of electrons31 e-
From Wikipedia, the free encyclopediaGallium is a chemical element with symbol Ga and atomic number 31. Elemental gallium does not occur in free form in nature, but as the gallium(III) compounds that are in trace amounts in zinc ores and in bauxite. Gallium is a soft, silvery metal, and elemental gallium is a brittle solid at low temperatures, and melts at 29.76 °C (85.57 °F) (slightly above room temperature).

Physical properties

Phase at STPSolid
Density5.91 g/cm3
Atomic weight69.7231 u

Thermal properties

Melting point302.915 K
29.765 °C
85.577 °F
Boiling point2673 K
2399.85 °C
4351.73 °F
Heat of vaporization256.06 kJ/mol

Atomic properties

Electronegativity (Pauling Scale)1.81
Electron affinity41 kJ/mol
Oxidation states−5, −4, −3, −2, −1, +1, +2, +3
(an amphoteric oxide)
Ionization energies
  1. 578.8 kJ/mol
  2. 1979.3 kJ/mol
  3. 2963 kJ/mol
  4. 6180 kJ/mol

Electron configuration for gallium

Electron configuration
Shorthand configuration
[Ar] 3d10 4s2 4p1
Electron configuration
Full configuration
1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p1
Electron configuration chart
Electrons per shell2, 8, 18, 3
Valence electrons 3
Valency electrons 3,1
Bohr model
GalliumElectron shell for Gallium, created by Injosoft ABGa
Figure: Shell diagram of Gallium (Ga) atom.
Orbital Diagram

The history of Gallium

PredictionDmitri Mendeleev (1871)
Discovery and first isolationPaul-Émile Lecoq de Boisbaudran (1875)
Discovery of gallium
In 1871, the existence of gallium was first predicted by Russian chemist Dmitri Mendeleev, who named it "eka-aluminium" from its position in his periodic table. He also predicted several properties of eka-aluminium that correspond closely to the real properties of gallium, such as its density, melting point, oxide character, and bonding in chloride. Gallium was discovered using spectroscopy by French chemist Paul Emile Lecoq de Boisbaudran in 1875 from its characteristic spectrum (two violet lines) in a sample of sphalerite. Later that year, Lecoq obtained the free metal by electrolysis of the hydroxide in potassium hydroxide solution. He named the element "gallia", from Latin Gallia meaning Gaul, after his native land of France.


List of unique identifiers for Gallium in various chemical registry databases
CAS Number7440-55-3
ChemSpider ID4514603
EC number231-163-8
PubChem CID Number5360835