11NaSodium22.98976928 u
Sodium (Na)
Sodium is an alkali metal with atomic number 11, in period 3 and group 1 of the periodic table. Its atomic mass is 22.98976928 u and its electron configuration is [Ne] 3s¹. Solid at 25 °C.
Key facts
| Atomic number | 11 |
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| Atomic mass | 22.98976928 u |
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| Category | Alkali Metal |
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| Period | 3 |
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| Group | 1 |
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| Block | s |
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| Electron configuration | [Ne] 3s¹ |
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| Electrons per shell | 2, 8, 1 |
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| Electronegativity (Pauling) | 0.93 |
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| Oxidation states | −1, +1common in bold |
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| State at 25 °C | Solid |
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| Melting point | 370.87 K97.72 °C |
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| Boiling point | 1156 K882.85 °C |
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| Density | 0.968 g/cm³ |
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Atomic properties
| First ionization energy | 5.139 eV |
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| Electron affinity | 52.8 kJ/mol |
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| Atomic radius | 190 pm |
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| Covalent radius | 166 pm |
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| Van der Waals radius | 227 pm |
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| Common ions | Na⁺ |
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| Protons, neutrons, electrons | 11, 12, 11 |
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Physical and thermal properties
| Molar volume | 23.78 cm³/mol |
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| Heat of fusion | 2.6 kJ/mol |
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| Heat of vaporization | 97.7 kJ/mol |
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| Specific heat | 1230 J/(kg·K) |
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| Thermal conductivity | 140 W/(m·K) |
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| Thermal expansion | 7 × 10⁻⁵ K⁻¹ |
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| Mohs hardness | 0.5 |
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| Young’s modulus | 10 GPa |
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| Crystal structure | Body-centered cubic |
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| Magnetic type | Paramagnetic |
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Identification and history
| CAS number | 7440-23-5 |
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| Latin name | Natrium |
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| Discovered by | Humphry Davy · 1807 |
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| Named by | --- |
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Natural isotopes
| Isotope | Mass (u) | Abundance |
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| 23Na | 22.989769 | 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