Periodic Table
13
Al
26.982
Aluminium
Post-transitionAmphoteric; passivated by oxide layer; extracted by Hall–Héroult.
Electronic Configuration
[Ne] 3s² 3p¹or1s² 2s² 2p⁶ 3s² 3p¹
Electron shells
2e⁻n=1
8e⁻n=2
3e⁻n=3
Properties
Atomic number
13
Atomic mass
26.982 u
Category
Post-transition
Block / Group / Period
p · 13 · 3
Valence electrons
3
Oxidation states
+3
Electronegativity
1.61
Atomic radius
118 pm
Ionization energy
578 kJ/mol
Electron affinity
42 kJ/mol
Melting point
933 K / 660 °C
Boiling point
2792 K / 2519 °C
Density
2.7 g/cm³
State at 25 °C
solid
JEE / NEET notes
- Diagonal relationship with Be.
- Amphoteric: reacts with both acids and alkalis.
- Passivated by oxide layer (resists corrosion).
- Thermite: 2Al + Fe₂O₃ → 2Fe + Al₂O₃ (highly exothermic).
Ores & extraction
Ores: Bauxite (Al₂O₃·2H₂O), Cryolite (Na₃AlF₆), Corundum
Extraction: Hall–Héroult — electrolysis of Al₂O₃ in molten cryolite.
Uses
Aircraft & utensils · Thermite welding · Packaging foil · Power cables
Important compounds
Al₂O₃Al₂(SO₄)₃AlCl₃Alums
Personal Notes
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