031Post-transition metal · Group 13 · Period 4
Gallium
Gallium (Ga) is element 31, a post-transition metal in the p-block — group 13, period 4. It is a solid at room temperature with 4 electron shells (2, 8, 18, 3) and an atomic mass of 69.7231 u.
- Atomic mass
- 69.72 u
- Phase · STP
- solid
- Melting
- 303 K · 30 °C
- Boiling
- 2673 K · 2400 °C
- Electronegativity
- 1.81
- Density
- 5.91 g/cm³
Photograph — Hi-Res Images ofChemical Elements, CC BY 3.0 <https://creativecommons.org/licenses/by/3.0>, via Wikimedia Commons, source: https://images-of-elements.com/gallium.php
Identity
- Atomic number
- 31
- Standard atomic weight
- 69.72 u
- Category
- Post-transition metal
- Group
- 13
- Period
- 4
- Block
- p-block
- Oxidation states
- +3
Physical properties
- Melting point
- 303 K · 30 °C
- Boiling point
- 2673 K · 2400 °C
- Density
- 5.91 g/cm³
- Molar heat capacity
- 25.86 J/(mol·K)
- Atomic radius
- 187 pm
- Electron affinity
- 41 kJ/mol
Atomic structure
31protons
39neutrons
31electrons
3valence e⁻
- Noble-gas notation
- [Ar] 3d10 4s2 4p1
- Full configuration
- 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p1
- Electrons per shell
- 2, 8, 18, 3
Periodic trends
Where Gallium ranks across all 118 elements.
Ionization energies
Energy to remove each successive electron (kJ/mol).
578.81
2.0k2
3.0k3
6.2k4
Successive ionization energies (kJ/mol, log scale).
Discovery
- Discovered
- 1875
- Discovered by
- Lecoq de Boisbaudran
- Named by
- —
- Appearance
- silver-white