Sodium
Sodium /ˈsoʊdiəm/ is a chemical element with symbol Na (from Ancient Greek Νάτριο) and atomic number 11. It is a soft, silver-white, highly reactive metal. In the Periodic table it is in column 1 (alkali metals), and shares with the other six elements in that column that it has a single electron in its outer shell, which it readily donates, creating a positively charged atom - a cation.
A stylized shell model. Electrons are quantum objects, not particles following these literal paths. Sizes and motion are illustrative.
10 is the [Ne] core total across two shells.
At a glance
- Atomic number
- 11
- Atomic mass
- 22.989769 u
- Phase
- Solid
- Density
- 0.968 g/cm³
- Melting point
- 370.944 K
- Boiling point
- 1,156.09 K
- First ionization energy
- 495.8 kJ/mol
- Electronegativity
- 0.93
- Electron affinity
- 52.867 kJ/mol
- Molar heat capacity
- 28.23 J/(mol·K)
- Period
- 3
- Appearance
- silvery white metallic
Conditions and isotopes affect measured properties. Some properties of short-lived elements are predicted. Electronegativity uses the Pauling scale.
Keep exploring
Explore the stories, imagery, and reference data in more depth. Properties with no value in the reference are marked unavailable.