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Aluminum (Al), element 13
Aluminum (Al) is the chemical element with atomic number 13: a post-transition metal in group 13, period 3. At 25 °C it is a solid, with an atomic mass of 26.98 u.
Physical and chemical data
| Atomic number | 13 |
|---|---|
| Symbol | Al |
| Atomic mass | 26.98 u |
| Density | 2.7 g/cm³ |
| Melting point | 660.29 °C (933.44 K) |
| Boiling point | 2,518.85 °C (2,792 K) |
| Electronegativity (Pauling) | 1.61 |
| Electron configuration | [Ne]3s2 3p1 |
| Atomic radius (van der Waals) | 184 pm |
| Oxidation states | +3 |
| Physical state at 25 °C | solid |
| Family | post-transition metal |
| Group and period | 13 / 3 |
| Discoverer and year | Hans Christian Ørsted (1825) |
The discovery record belongs to Hans Christian Ørsted, in 1825.
Neighbours on the table
Horizontally, one proton less lands on Magnesium (Z=12); one more lands on Silicon (Z=14). Vertically, group 13 gathers relatives with similar behaviour: Boron, Gallium, Indium, Thallium.
The story behind the name
The name comes from the Latin alumen, alum, the bitter salt Roman dyers used to fix colours in cloth. The metal was only isolated in 1825, by the Dane Ørsted, and was so hard to produce that it outpriced gold: Napoleon III reserved aluminium cutlery for guests of honour while the rest of the table ate with gold, and the Washington Monument was capped with an aluminium pyramid in 1884 as a luxury statement. The Hall-Héroult process of 1886 crashed the price and turned the precious metal into sandwich wrap. Its spelling still splits English: aluminium in Europe, aluminum in the United States.
Physical and chemical data: PubChem Periodic Table (NCBI, compiling NIST and IUPAC), public domain, snapshot of 2026-07-10. Temperatures converted from kelvin; historical notes cross checked against classic chemistry references.
Last updated: · Methodology and sources