Element 31 · Post-transition metal
Gallium (Ga) — Element 31
Latin Gallia — France
Gallium (Ga) is a post-transition metal in Period 4, Group 13 of the periodic table with atomic number 31, standard atomic weight 69.723 u, and ground-state electron configuration [Ar] 3d¹⁰ 4s² 4p¹. At standard temperature and pressure it is classified as a solid with 3 valence electrons and common oxidation states +3.
Semiconductors, thermometers
What are the atomic properties and physical constants of Gallium?
Reference constants compiled from IUPAC standard atomic weights, the NIST Atomic Spectra Database, and the CRC Handbook.
- Atomic number (Z)
- 31
- Standard atomic mass
- 69.723 u
- Chemical family
- Post-transition metal
- Ground-state configuration
- [Ar] 3d¹⁰ 4s² 4p¹
- Electrons per shell
- 2, 8, 18, 3
- Valence electrons
- 3
- Common ion charges / oxidation states
- +3
- Phase at STP
- Solid
- Pauling electronegativity
- 1.81 Pauling
- First ionization energy
- 579 kJ/mol
- Atomic radius
- 136 pm
- Melting point
- 30 °C
- Boiling point
- 2,403 °C
- Discovery year
- 1875
- Table coordinate
- Period 4, Group 13
- Radioactivity
- Has stable isotope(s)
How are electrons arranged across Gallium’s shells?
A neutral Gallium atom contains 31 electrons distributed across 4 occupied principal energy shells ([Ar] 3d¹⁰ 4s² 4p¹). The table below compares Gallium’s shell occupancy against each shell’s theoretical 2n² capacity.
| Principal Shell (n) | Spectroscopic Letter | Electrons in Ga | Max Shell Capacity (2n²) |
|---|---|---|---|
| n = 1 | K | 2 e⁻ | 2 e⁻ |
| n = 2 | L | 8 e⁻ | 8 e⁻ |
| n = 3 | M | 18 e⁻ | 18 e⁻ |
| n = 4 | N | 3 e⁻ | 32 e⁻ |
Frequently Asked Questions about Gallium (Ga)
What is the atomic mass and atomic number of Gallium (Ga)?
Gallium (Ga) has atomic number Z = 31 (31 protons in its nucleus) and an IUPAC standard atomic weight of 69.723 u. It sits in Period 4, Group 13 and is classified as a post-transition metal.
What is the ground-state electron configuration of Gallium?
The neutral ground-state electron configuration of Gallium (Z = 31) is [Ar] 3d¹⁰ 4s² 4p¹. Across its 4 occupied principal shells (n = 1 to n = 4), the electrons per shell are 2, 8, 18, 3, with 3 valence electrons participating in bonding.
What are the common ion charges and electronegativity of Gallium?
Gallium commonly forms +3 oxidation states or ion charges in compounds. Its Pauling electronegativity is 1.81 and its first ionization energy is 579 kJ/mol.
When was Gallium discovered and what is it used for?
Gallium was discovered in 1875 (Latin Gallia — France). Semiconductors, thermometers
How does Gallium compare to neighboring elements?
Other post-transition metal elements: