Aluminium (Al)
Post-transition metal
Aluminium is the most abundant metal in the Earth's crust — light, strong, corrosion-resistant and endlessly recyclable. A thin invisible oxide layer forms instantly on its surface and protects it.
Position on the periodic table
Atomic properties
| Atomic number | 13 |
|---|---|
| Atomic mass | 26.9815 amu |
| Electron configuration | 1s2 2s2 2p6 3s2 3p1 |
| Noble gas shorthand | [Ne] 3s2 3p1 |
| Electrons per shell | 2, 8, 3 |
| Valence electrons (outer shell) | 3 |
| Common oxidation states | +3 |
| Electronegativity (Pauling) | 1.61 |
| Covalent radius (approx.) | 121 pm |
| First ionization energy | 577.5 kJ/mol |
| Electron affinity | 41.8 kJ/mol |
Physical properties
| State at 25 °C | Solid |
|---|---|
| Density | 2.7 g/cm³ |
| Melting point | 660.32 °C (933.47 K) |
| Boiling point | 2469.8 °C (2743 K) |
| Appearance | silvery gray metallic |
| Radioactive | No |
| Origin | Occurs naturally |
Electron configuration of aluminium
Aluminium's ground-state electron configuration is 1s2 2s2 2p6 3s2 3p1, usually shortened to [Ne] 3s2 3p1. Its electrons occupy 3 shells (2, 8, 3), placing it in period 3 of the p-block. The 3 outer-shell electrons drive its bonding behaviour. Explore it interactively in the electron configuration calculator.
Uses of aluminium
- Drink cans, foil and food packaging
- Aircraft, cars and bicycles
- Window frames and construction
- Overhead power lines
Biological role: No known biological role.
Occurrence: About 8% of the Earth's crust — the most abundant metal — mined mainly as bauxite.
Common compounds of aluminium
Al2O3
Aluminium oxide (alumina)
Al(OH)3
Aluminium hydroxide
Al2(SO4)3
Aluminium sulfate
History and discovery
Discovered: 1825. Name origin: From alum (Latin alumen), a bitter aluminium salt used since antiquity.
Hans Christian Ørsted produced impure aluminium in 1825. It stayed more precious than gold until cheap electrolytic production arrived in 1886.
Safety notes
Everyday aluminium products are safe; fine aluminium powder is flammable.
Educational context only — always follow your school's laboratory rules and never handle chemicals without proper supervision. See our disclaimer.
Practice questions
Quick practice: Aluminium
1. What is the chemical symbol of Aluminium?
2. What is the atomic number of Aluminium?
3. Which category does Aluminium belong to?
4. What is the state of Aluminium at room temperature?
5. Which period of the periodic table is Aluminium in?
Aluminium FAQs
What is the atomic number of aluminium?
Aluminium's atomic number is 13 — every aluminium atom has 13 protons in its nucleus.
What is the symbol for aluminium?
Al. From alum (Latin alumen), a bitter aluminium salt used since antiquity.
Is aluminium a metal, nonmetal, or metalloid?
Aluminium is classified as a post-transition metal.
What state is aluminium at room temperature?
At about 25 °C, aluminium is a solid. It melts at 660.32 °C.
How many valence electrons does aluminium have?
Aluminium has 3 electrons in its outer shell (shell pattern: 2, 8, 3).
What is aluminium used for?
Key uses include: drink cans, foil and food packaging; aircraft, cars and bicycles; window frames and construction.
Related elements
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