31GaGallium69.7231[Ar] 3d¹⁰ 4s² 4p¹
post-transition metal

Gallium

Gallium 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).

Electronic structure

A stylized shell model. Electrons are quantum objects, not particles following these literal paths. Sizes and motion are illustrative.

Electrons by shell
Electron configuration
3d10
4s2
4p1

18 is the [Ar] core total across three shells.

Properties

At a glance

Atomic number
31
Atomic mass
69.7231 u
Phase
Solid
Density
5.91 g/cm³
Melting point
302.9146 K
Boiling point
2,673 K
First ionization energy
578.8 kJ/mol
Electronegativity
1.81
Electron affinity
41 kJ/mol
Molar heat capacity
25.86 J/(mol·K)
Period
4
Appearance
silver-white

Conditions and isotopes affect measured properties. Some properties of short-lived elements are predicted. Electronegativity uses the Pauling scale.

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