Aluminum
Silvery-white lustrous metallic element of group 3 of the periodic table. Highly reactive but protected by a thin transparent layer of the oxide which quickly forms in air. There are many alloys of aluminum, as well as a good number of industrial uses. Makes up 8.1% of the Earth's crust, by weight. Isolated in 1825 by H.C. Oersted.
Gallery
Jurii, CC BY 3.0 <https://creativecommons.org/licenses/by/3.0>, via Wikimedia Commons, source: https://images-of-elements.com/aluminium.php
Physical Propertiesmass · density · phase · crystal
Atomic Mass
26.9815Da
Density
2.7000g/cm³
Phase (STP)
Solid
Melting Point
933.5K
Boiling Point
2792.2K
Molar Heat
0.8970J/(mol·K)
Crystal Structure
FCC
Lattice Constant
4.050Å
Atomic Radiiatomic · covalent · van der Waals
Atomic (Empirical)
125.00pm
Covalent
126.00pm
Van der Waals
184.00pm
Electronic Propertieselectronegativity · ionization · affinity
Electron Configuration
[Ne] 3s2 3p
Electron Shells
2, 8, 3
Electronegativity
1.61Pauling
Electron Affinity
0.4kJ/mol
1st Ionization Energy
6.0kJ/mol
Oxidation States
+1, +3
Orbital DiagramAufbau · Hund's rule · Pauli exclusion
Full: 1s2 2s2 2p6 3s2 3p1Short: [Ne] 3s2 3p
Ionization Energies (13 known)
Emission Spectrumvisible range · characteristic spectral lines
Abundanceby mass
Log scale · ppm = parts per million by mass
Biological Role
No known biological role. Possible neurotoxin at high levels; debated link to Alzheimer's.
Discovery
Discovered By
Hans Christian Oersted
Named By
—
Year
1825
Nuclear Data
Known Isotopes
23
Stable Isotopes
2
Stable Mass Numbers
21, 27
Natural isotopic abundance (IUPAC recommended values)
Isotopes of Al23 known
| Nuclide | Z | N | Mass (AMU) | Half-life | Decay | Jπ | Abundance |
|---|---|---|---|---|---|---|---|
| 21Alstable | 13 | 8 | 21.029082 | Stable | p | 5/2+ | — |
| 22Al | 13 | 9 | 22.019540 | 91.1 ms | β⁺ (1%), β⁺p (0.55%), 2p (0.011000000000000001%), β⁺α (0.00037999999999999997%) | 4 | — |
| 23Al | 13 | 10 | 23.007244 | 446 ms | β⁺ (1%), β⁺p (0.012199999999999999%) | 5/2+ | — |
| 27Alstable | 13 | 14 | 26.981538 | Stable | stable (1%) | 5/2+ | 10000.0000% |
| 41Al | 13 | 28 | 41.037134 | Unknown | β⁻, β⁻n, 2n | 5/2+ | — |
| 42Al | 13 | 29 | 42.045078 | Unknown | β⁻, β⁻n, 2n | — | — |
| 43Al | 13 | 30 | 43.051820 | Unknown | β⁻, β⁻n, 2n | 5/2+ | — |