Aluminum (Al)

Silvery-white metal

Aluminum is the most abundant metal in Earth's crust, lightweight and corrosion-resistant, and with the electron configuration [Ne] 3s² 3p¹, aluminum forms a self-healing Al₂O₃ oxide layer just 4 nm thick. It has high thermal and electrical conductivity and is the third most abundant element overall.

Key metrics

Density2.7g/cm³

Melting point933.47K

Boiling point2,792K

Electronegativity1.61Pauling

Discovery

1825discovered

Discovered by: Hans Christian Ørsted
Reactivity profile: Oxidizes but forms protective layer
Reactivity: Medium
Bonding: Metallic

Electron configuration

\textcolor{#6b7280}{[Ne]}\; \textcolor{#ef4444}{3_{s}^{2}}\; \textcolor{#3b82f6}{3_{p}^{1}}

[Ne] 3s2 3p1

Wave function

\Psi_{\text{Al}} \approx \frac{1}{\sqrt{13!}} \det \left| \chi_1(\mathbf{r}_1) \dots \chi_{13}(\mathbf{r}_{13}) \right|

Probability density $|\Psi|^2$ across the Al valence shell.

Crystal structure

Face-Centered Cubic

Lattice constantsa = 1.00

Cell anglesα = β = γ = 90°

Coordination number12

Atoms per cell4

Atomic packing factor0.74

Physical properties

Atomic radius: 143 pm
Ionization energy: 578 kJ/mol
Electron affinity: 42.5 kJ/mol
Crystal structure: Face-centered cubic (fcc)

Oxidation states

Acid/base

Can act as acid or base

Strongly acidicStrongly basic

State at 25 °CSolid

933.47 K2792 K298 K

Emission spectrum

4 transitions

380450500550600650700780

VioletBlueGreenYellowRed

309.3nmAl I (UV)UV60%

394.4nmAl I (violet)UV100%

396.2nmAl I (violet)UV95%

669.6nmAl I (red)Red30%

Dominant line 394.4 nmRange 309–670 nmTransitions 4