13AlAluminum26.9815384 u
Aluminum (Al)
Aluminum is a post-transition metal with atomic number 13, in period 3 and group 13 of the periodic table. Its atomic mass is 26.9815384 u and its electron configuration is [Ne] 3s² 3p¹. Solid at 25 °C.
Key facts
| Atomic number | 13 |
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| Atomic mass | 26.9815384 u |
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| Category | Post-Transition Metal |
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| Period | 3 |
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| Group | 13 |
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| Block | p |
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| Electron configuration | [Ne] 3s² 3p¹ |
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| Electrons per shell | 2, 8, 3 |
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| Electronegativity (Pauling) | 1.61 |
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| Oxidation states | −2, −1, +1, +2, +3common in bold |
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| State at 25 °C | Solid |
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| Melting point | 933.47 K660.32 °C |
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| Boiling point | 2792 K2518.85 °C |
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| Density | 2.7 g/cm³ |
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Atomic properties
| First ionization energy | 5.986 eV |
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| Electron affinity | 42.5 kJ/mol |
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| Atomic radius | 143 pm |
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| Covalent radius | 121 pm |
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| Van der Waals radius | 184 pm |
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| Common ions | Al³⁺ |
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| Protons, neutrons, electrons | 13, 14, 13 |
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Physical and thermal properties
| Molar volume | 10 cm³/mol |
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| Heat of fusion | 10.7 kJ/mol |
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| Heat of vaporization | 293 kJ/mol |
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| Specific heat | 904 J/(kg·K) |
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| Thermal conductivity | 235 W/(m·K) |
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| Thermal expansion | 2.31 × 10⁻⁵ K⁻¹ |
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| Mohs hardness | 2.75 |
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| Young’s modulus | 70 GPa |
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| Crystal structure | Face-centered cubic |
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| Magnetic type | Paramagnetic |
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Identification and history
| CAS number | 7429-90-5 |
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| Latin name | Aluminum |
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| Discovered by | Hans C. Ørsted · 1825 |
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| Named by | Humphry Davy · 1812 |
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Natural isotopes
| Isotope | Mass (u) | Abundance |
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| 27Al | 26.981538 | 100 % |
Data checked against PubChem (NIH), IUPAC, the NIST Atomic Spectra Database and the IAEA (NUBASE and AME), the same data you see in the app.
A dash (---) means there is no reliable published measurement. The app never makes one up.
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Periodic Table