ElementsWhat is sodium?
Sodium is a soft, silvery metal that reacts strongly with water, so it is stored under oil. It is very common in nature as salt, in the sea and in rock salt beds.
What is sodium used for?
Table salt (sodium chloride), baking soda, soap making, yellow street lamps, and as a coolant in some nuclear reactors.
Where the name comes from
From soda, a common sodium compound. The symbol Na comes from natrium, its Latin name.
Key facts
- Symbol
- Na
- Atomic number
- 11
- Atomic mass
- 22.9897693 u
- Family
- Alkali metal
- Period
- 3
- Group
- 1
- Block
- s
- State at room temperature
- Solid
- Melting point
- 97.8 °C (370.95 K, 208 °F)
- Boiling point
- 882.9 °C (1,156 K, 1,621 °F)
- Density
- 0.97 g/cm³
- Electrons per shell
- 2, 8, 1
- Electron configuration
- [Ne]3s1
- Common oxidation states
- +1
- Electronegativity (Pauling)
- 0.93
- First ionisation energy
- 5.139 eV
- Electron affinity
- 0.548 eV
- Atomic radius (van der Waals)
- 227 pm
- Discovered
- 1807
Place in the periodic table
Sodium is element number 11. It sits in period 3 (row 3) of the periodic table, in group 1 (column 1), and belongs to the s-block. Just before it comes neon (10), and just after it comes magnesium (12). In the same column, lithium is above it and potassium is below it. Elements in one column tend to behave alike.
Family: Alkali metals.
Physical properties
At room temperature sodium is a solid. It melts at 97.8 °C and boils at 882.9 °C, so it stays liquid over a range of 785 degrees. Its density is 0.97 grams per cubic centimetre, so a one-litre block would weigh about 0.97 kilograms. It is lighter than water and would float, if it did not react with it.
Inside the atom
An atom of sodium has 11 protons in its nucleus and, when neutral, 11 electrons around it. The electrons are arranged in 3 shells: 2, 8, 1. The outermost shell holds 1 electron. Written in full, the electron configuration is [Ne]3s1.
Its electronegativity on the Pauling scale is 0.93. This number shows how strongly an atom pulls shared electrons towards itself: fluorine, the strongest, is 3.98. Removing one electron from an atom takes 5.139 electronvolts (about 496 kilojoules per mole). One mole of sodium weighs 22.9897693 grams, so a single gram contains about 2.62 × 1022 atoms.
The ring picture is a simple model that only counts the electrons in each shell. Real atoms do not look like this.
Next steps
- Work out the weight of a compound that contains sodium with the molar mass calculator.
- Compare it with every other element in the sortable list.
- Test yourself with the symbol quiz.
Figures on this page are from PubChem (U.S. National Library of Medicine), as downloaded on 11 November 2026. See About and data sources.