1122.99NaSodium
Sodium (Na) — element 11alkali metal · group 1, period 3
Sodium is a chemical element with the symbol Na and atomic number 11. It is an alkali metal in group 1, period 3 of the periodic table (the s-block), with a standard atomic mass of 22.99 u. At room temperature (25 °C) sodium is a solid.
💡 Known for: A soft, highly reactive metal; combined with chlorine it forms table salt (sodium chloride).
# Sodium properties
| Symbol | Na |
|---|---|
| Atomic number | 11 |
| Atomic mass | 22.99 u |
| Category | alkali metal |
| Group | 1 |
| Period | 3 |
| Block | s-block |
| Electron configuration | [Ne] 3s¹ |
| Full configuration | 1s² 2s² 2p⁶ 3s¹ |
| Electrons per shell | 2, 8, 1 |
| Protons / electrons | 11 / 11 |
| State at 25 °C | solid |
| Melting point | 370.87 K (97.7 °C, 207.9 °F) |
| Boiling point | 1156 K (882.9 °C, 1621.1 °F) |
| Density | 0.971 g/cm³ |
| Electronegativity (Pauling) | 0.93 |
| First ionization energy | 5.139 eV |
| Atomic radius | 190 pm |
| Discovered | 1807 |
# Electron configuration of sodium
The electron configuration of sodium is [Ne] 3s¹, written out in full as 1s² 2s² 2p⁶ 3s¹. Its 11 electrons fill 3 shells as 2, 8, 1, so the outermost shell holds 1 electron. As a group 1 element, sodium has 1 valence electron.
# Related elements
NeNeonprevious elementMgMagnesiumnext elementHHydrogengroup 1LiLithiumgroup 1KPotassiumgroup 1RbRubidiumgroup 1CsCaesiumgroup 1FrFranciumgroup 1
# Sodium FAQ
What is the atomic number of sodium?
The atomic number of sodium is 11: every sodium atom has 11 protons in its nucleus. Its symbol is Na.
What is the atomic mass of sodium?
The standard atomic mass of sodium is 22.99 u.
What is the electron configuration of sodium?
Sodium's electron configuration is [Ne] 3s¹ (1s² 2s² 2p⁶ 3s¹), with 2, 8, 1 electrons per shell.
Is sodium a metal?
Yes. Sodium is an alkali metal, one of the metals.
What is the melting point of sodium?
Sodium melts at 370.87 K (97.7 °C, 207.9 °F) and boils at 1156 K (882.9 °C, 1621.1 °F).
What is sodium used for / known for?
A soft, highly reactive metal; combined with chlorine it forms table salt (sodium chloride).