Gallium (Ga): Electron Configuration, Properties and Uses
Gallium (Ga): Electron Configuration, Properties and Uses
Electron configuration [Ar] 4s2 3d10 4p1 · group 13 · period 4 · Ar 69.723
Gallium data
- Atomic number
- 31
- Relative atomic mass
- 69.723
- Group
- 13
- Period
- 4
- Block
- p
- Category
- Post-transition metal
- Electron configuration
- [Ar] 4s2 3d10 4p1
- Full configuration
- 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p1
- Electrons per shell
- 2, 8, 18, 3 (K L M N)
- Valence electrons
- 3
- Electronegativity (Pauling)
- 1.81
- First ionisation energy
- 5.999 eV
- Atomic radius (van der Waals)
- 187 pm
- State at room temperature
- Solid
- Melting point
- 29.8 °C
- Boiling point
- 2204 °C
- Density
- 5.91 g/cm³
- Common oxidation states
- +3
- Discovered
- 1875
Source: PubChem (NIH, accessed 13 Nov 2026); atomic mass: IUPAC standard atomic weight.
Electron shell diagram
K 2 · L 8 · M 18 · N 3
Orbital diagram (outer electrons)
About gallium
With atomic number 31, gallium (Ga) has 31 protons in its nucleus and 31 electrons as a neutral atom. It is a post-transition metal in group 13, period 4, p-block. The element was discovered in 1875. Gallium is solid at room temperature, but it melts at only 29.8 °C, so it can melt in your hand.
Gallium electron configuration
The electron configuration of gallium is 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p1, or in short [Ar] 4s2 3d10 4p1. Its electrons occupy 4 shells: K = 2, L = 8, M = 18, N = 3. Gallium has 3 valence electrons in the N shell (4s2 4p1), which is why it sits in group 13. When it forms cations, electrons leave the outermost subshell first: Ga3+ = [Ar] 3d10.
Filling order: 1s2(2) → 2s2(4) → 2p6(10) → 3s2(12) → 3p6(18) → 4s2(20) → 3d10(30) → 4p1(31)
Uses of gallium
In industry and the laboratory, gallium turns up in many places, for example GaAs and GaN semiconductors for LEDs and fast chargers, and high-temperature thermometers.
Safety
Bulk gallium has low toxicity. The main hazards are its dust and salts, so always check the SDS of the compound you use. Always read the safety data sheet (SDS) before working with a chemical.
Other elements in group 13
Frequently asked questions
What is the electron configuration of gallium?
The electron configuration of gallium (Ga, atomic number 31) is 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p1, or [Ar] 4s2 3d10 4p1 in short. By shell: 2, 8, 18, 3.
How many valence electrons does gallium have?
Gallium has 3 valence electrons.
Which group and period is gallium in?
Gallium is in group 13, period 4, p-block.
What is the atomic mass of gallium?
The relative atomic mass of gallium is 69.723. Use it to calculate molar mass with the molar mass calculator.
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