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Post-transition metals

Gallium

A soft metal that melts in the warmth of your hand.

Atomic #31Mass69.723Blockp-blockPeriod4Group13
Ga31 · 69.723
3D Atom Explorer

Inside the Gallium atom

Switch between Bohr and Quantum Cloud modes to compare a simple teaching model with a more realistic probability-based view, and follow the guided tour to explore the Gallium atom step by step.

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Electron configuration

[Ar] 3d10 4s2 4p1

A neutral Gallium atom has 31 electrons (equal to its proton count). Choosing a different isotope above changes only the neutron count.

Shell distribution

Shell 12 e⁻Shell 28 e⁻Shell 318 e⁻Shell 43 e⁻

Electrons fill inner shells before outer ones; the outermost (valence) shell drives the element's chemistry.

Properties

Physical & atomic properties

State (room temp)
Solid
Melting point
303 K (30 °C)
Boiling point
2673 K (2400 °C)
Density
5.907 g/cm³
Electronegativity
1.81 Pauling
Atomic radius
130 pm
1st ionization energy
579 kJ/mol
Category
Post-transition metals
History

Discovery & naming

Discovered
1875
Discovered by
Paul-Émile Lecoq de Boisbaudran
Origin of name
Latin 'Gallia', for France.

Notable uses

LEDs, high-speed semiconductors, and solar cells.

Cosmic origin

Where Gallium comes from

Several comparable sources

Both slow neutron capture in dying stars and rapid capture in explosive events contribute meaningfully.

Simplified origin map — many elements form through more than one astrophysical pathway.

Summary

Atomic number
31
Atomic mass
69.723
Category
Post-transition metals
Group · Period
13 · 4
Block
p-block
Shells
2 · 8 · 18 · 3