Element: Aluminium
General data
| Element name | Aluminium |
|---|---|
| Chemical symbol | Al |
| Atomic number Z | 13 |
| Year discovered | known since antiquity |
| Standard state (25°C) | Solid |
| Category | Post-transition metal |
| Block | p |
| Atomic mass | 26.982 |
| CPK color | #BFA6A6 |
Physical properties
| Melting point | 933.437 K (660.287 °C) |
|---|---|
| Boiling point | 2792 K (2519 °C) |
| Density | 2.7 g/cm³ |
Energy properties
| First ionization energy | 5.986 eV |
|---|---|
| Electron affinity | 0.441 eV |
Atomic structure
| Protons | 13 (Atomic number) |
|---|---|
| Neutrons (Al-27, most abundant isotope) | 14 |
| Electrons | 13 |
| Electron configuration | [Ne] 3s² 3p¹ |
| Oxidation states | +3 |
| Electronegativity (Pauling) | 1.61 |
| Atomic radius (van der Waals) | 184 pm |
Ionization energies - NIST ASD (13 states)
| State | Charge | Ioniz. energy (eV) | Type |
|---|---|---|---|
| Al I | 0+ | 5.985769 ± 0.000003 | measured |
| Al II | 1+ | 18.82855 ± 0.00005 | measured |
| Al III | 2+ | 28.447642 ± 0.000025 | measured |
| Al IV | 3+ | 119.9924 ± 0.0019 | measured |
| Al V | 4+ | 153.8252 ± 0.0025 | semi-empirical |
| Al VI | 5+ | 190.49 ± 0.05 | semi-empirical |
| Al VII | 6+ | 241.76 ± 0.09 | semi-empirical |
| Al VIII | 7+ | 284.64 ± 0.07 | semi-empirical |
| Al IX | 8+ | 330.21 ± 0.04 | semi-empirical |
| Al X | 9+ | 398.65 ± 0.06 | semi-empirical |
| Al XI | 10+ | 442.005 ± 0.007 | calculated |
| Al XII | 11+ | 2085.97693 ± 0.00016 | calculated |
| Al XIII | 12+ | 2304.140359 ± 0.000012 | calculated |
Value type as given by NIST ASD: measured - from evaluated experimental data; calculated - from ab initio calculations (mostly highly ionised atoms that have not been measured; for the simplest ones, e.g. H I, the calculation is more accurate than measurement); semi-empirical - from interpolation, extrapolation or another semi-empirical method.
Photos
Isotopes (23)
| A | N | Half-life | Decay |
|---|---|---|---|
| Al-21 | 8 | < 35 ns | p |
| Al-22 | 9 | 89 ms | EC/β⁺ |
| Al-23 | 10 | 450 ms | EC/β⁺ |
| Al-24 | 11 | 2.053 s | EC/β⁺ |
| Al-25 | 12 | 7.167 s | EC/β⁺ |
| Al-26 | 13 | 7.17×10⁵ a | EC/β⁺ |
| Al-27 | 14 | stable | - |
| Al-28 | 15 | 2.2483 min | β⁻ |
| Al-29 | 16 | 6.56 min | β⁻ |
| Al-30 | 17 | 3.61 s | β⁻ |
| Al-31 | 18 | 0.64 s | β⁻ |
| Al-32 | 19 | 31.7 ms | β⁻ |
| Al-33 | 20 | 41.5 ms | β⁻ |
| Al-34 | 21 | 53.73 ms | β⁻ |
| Al-35 | 22 | 38.4 ms | β⁻ |
| Al-36 | 23 | 90 ms | β⁻ |
| Al-37 | 24 | 11.4 ms | β⁻ |
| Al-38 | 25 | 9.0 ms | β⁻ |
| Al-39 | 26 | 7.2 ms | β⁻ |
| Al-40 | 27 | 5.7 ms | β⁻ |
| Al-41 | 28 | 3.5 ms | β⁻ |
| Al-42 | 29 | unknown | β⁻ |
| Al-43 | 30 | unknown | β⁻ |
Data sources
- PubChem Periodic Table API - Retrieved on 29 June 2026 - licence: CC0
- IUPAC CIAAW - Abridged Standard Atomic Weights 2024 - Table version: 2024 - licence: Public domain
- NNDC Wallet Cards 2023 - Data as of 15 October 2024 - licence: Public domain
- NIST Atomic Spectra Database (ASD) - Retrieved on 29 June 2026 - licence: © U.S. Secretary of Commerce
- Images of Elements - Retrieved on 29 June 2026 - licence: CC BY 3.0