Alkali metals
Sodium
A soft, reactive metal half of common table salt.
Atomic #11Mass22.990Blocks-blockPeriod3Group1
Na11 · 22.990
3D Atom Explorer
Inside the Sodium atom
Switch between Bohr and Quantum Cloud modes to compare a simple teaching model with a more realistic probability-based view, and follow the guided tour to explore the Sodium atom step by step.
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Electron configuration
[Ne] 3s1
A neutral Sodium atom has 11 electrons (equal to its proton count). Choosing a different isotope above changes only the neutron count.
Shell distribution
Shell 12 e⁻Shell 28 e⁻Shell 31 e⁻
Electrons fill inner shells before outer ones; the outermost (valence) shell drives the element's chemistry.
Properties
Physical & atomic properties
- State (room temp)
- Solid
- Melting point
- 371 K (98 °C)
- Boiling point
- 1156 K (883 °C)
- Density
- 0.971 g/cm³
- Electronegativity
- 0.93 Pauling
- Atomic radius
- 180 pm
- 1st ionization energy
- 496 kJ/mol
- Category
- Alkali metals
History
Discovery & naming
- Discovered
- 1807
- Discovered by
- Humphry Davy
- Origin of name
- English 'soda'; symbol from Latin 'natrium'.
Notable uses
Table salt, street lighting, and heat-transfer coolant.
Cosmic origin
Where Sodium comes from
Stellar fusion and dying stars
Produced during carbon burning in the interiors of massive stars.
Simplified origin map — many elements form through more than one astrophysical pathway.
Summary
- Atomic number
- 11
- Atomic mass
- 22.990
- Category
- Alkali metals
- Group · Period
- 1 · 3
- Block
- s-block
- Shells
- 2 · 8 · 1