Sodium (Na) – element 11
Sodium is a chemical element with the symbol Na and atomic number 11. It is a alkali metal in group 1 (alkali metals), period 3 of the periodic table (s-block), and is a solid at room temperature.
Sodium (Na) has atomic number 11, atomic mass 22.99 u and electron configuration [Ne] 3s1.
Sodium facts
| Symbol | Na |
|---|---|
| Atomic number | 11 |
| Atomic mass | 22.99 u (g/mol) |
| Category | alkali metal |
| Group | group 1 (alkali metals) |
| Period | 3 |
| Block | s-block |
| Phase at 20 °C | Solid |
| Electron configuration | 1s2 2s2 2p6 3s1 |
| Noble-gas notation | [Ne] 3s1 |
| Electrons per shell | 2, 8, 1 |
| Valence electrons | 1 |
Bohr model and shells
Sodium has 11 electrons in 3 shells: 2, 8, 1. Full configuration and noble-gas notation are in the table; work out any element or ion with the electron configuration calculator.
Physical and atomic properties
| Melting point | 370.944 K (97.8 °C) |
|---|---|
| Boiling point | 1156.09 K (882.9 °C) |
| Density | 0.968 g/cm³ |
| Electronegativity (Pauling) | 0.93 |
| Electron affinity | 52.867 kJ/mol |
| Ionization energies | 495.8, 4562, 6910.3 kJ/mol (1st, 2nd, 3rd) |
| Molar heat capacity | 28.23 J/(mol·K) |
| Discovered by | Humphry Davy |
Use the atomic mass in the molar mass calculator for any formula containing Na.
Position in the periodic table
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Frequently asked questions
What is the atomic mass of sodium?
The atomic mass of sodium is 22.99 u, so one mole of sodium atoms weighs 22.99 g.
What is the electron configuration of sodium?
Sodium has 11 electrons: 1s² 2s² 2p⁶ 3s¹, or [Ne] 3s¹ in noble-gas notation. Electrons per shell: 2, 8, 1.
How many valence electrons does sodium have?
Sodium has 1 valence electron (group 1).
Is sodium a metal?
Yes. Sodium is a alkali metal.
Where is sodium on the periodic table?
Sodium is in group 1 (alkali metals), period 3, in the s-block.
Data: Periodic-Table-JSON (CC BY-SA 3.0); standard atomic weights from IUPAC (abridged). Values in brackets are the mass number of the longest-lived isotope.