Gallium (Ga)
Post-transition metal
Gallium is a soft, silvery metal with a party trick: it melts at about 30 °C, so a piece will liquefy in your hand. Combined with arsenic or nitrogen it becomes the heart of LEDs and high-speed electronics.
Position on the periodic table
Atomic properties
| Atomic number | 31 |
|---|---|
| Atomic mass | 69.7231 amu |
| Electron configuration | 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p1 |
| Noble gas shorthand | [Ar] 3d10 4s2 4p1 |
| Electrons per shell | 2, 8, 18, 3 |
| Valence electrons (outer shell) | 3 |
| Common oxidation states | +3 |
| Electronegativity (Pauling) | 1.81 |
| Covalent radius (approx.) | 122 pm |
| First ionization energy | 578.8 kJ/mol |
| Electron affinity | 41 kJ/mol |
Physical properties
| State at 25 °C | Solid |
|---|---|
| Density | 5.91 g/cm³ |
| Melting point | 29.76 °C (302.91 K) |
| Boiling point | 2399.8 °C (2673 K) |
| Appearance | silver-white |
| Radioactive | No |
| Origin | Occurs naturally |
Electron configuration of gallium
Gallium's ground-state electron configuration is 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p1, usually shortened to [Ar] 3d10 4s2 4p1. Its electrons occupy 4 shells (2, 8, 18, 3), placing it in period 4 of the p-block. The 3 outer-shell electrons drive its bonding behaviour. Explore it interactively in the electron configuration calculator.
Uses of gallium
- LEDs and laser diodes (GaN, GaAs)
- High-frequency chips for phones and satellites
- Solar cells
- Low-melting safety alloys
Biological role: None known.
Occurrence: A trace by-product of aluminium and zinc refining.
Common compounds of gallium
GaAs
Gallium arsenide
GaN
Gallium nitride
History and discovery
Discovered: 1875 — Lecoq de Boisbaudran. Name origin: From Gallia, the Latin name for France, homeland of its discoverer.
Paul-Émile Lecoq de Boisbaudran found gallium in 1875 — the first of Mendeleev's predicted elements to be discovered.
Safety notes
Gallium metal is low-toxicity but wets and stains skin and attacks aluminium.
Educational context only — always follow your school's laboratory rules and never handle chemicals without proper supervision. See our disclaimer.
Practice questions
Quick practice: Gallium
1. What is the chemical symbol of Gallium?
2. What is the atomic number of Gallium?
3. Which category does Gallium belong to?
4. What is the state of Gallium at room temperature?
5. Which period of the periodic table is Gallium in?
Gallium FAQs
What is the atomic number of gallium?
Gallium's atomic number is 31 — every gallium atom has 31 protons in its nucleus.
What is the symbol for gallium?
Ga. From Gallia, the Latin name for France, homeland of its discoverer.
Is gallium a metal, nonmetal, or metalloid?
Gallium is classified as a post-transition metal.
What state is gallium at room temperature?
At about 25 °C, gallium is a solid. It melts at 29.76 °C.
How many valence electrons does gallium have?
Gallium has 3 electrons in its outer shell (shell pattern: 2, 8, 18, 3).
What is gallium used for?
Key uses include: leds and laser diodes (gan, gaas); high-frequency chips for phones and satellites; solar cells.
Related elements
Keep working with this element
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