011Alkali metal · Group 1 · Period 3
Sodium
Sodium (Na) is element 11, a alkali metal in the s-block — group 1, period 3. It is a solid at room temperature with 3 electron shells (2, 8, 1) and an atomic mass of 22.989769282 u.
- Atomic mass
- 22.99 u
- Phase · STP
- solid
- Melting
- 371 K · 98 °C
- Boiling
- 1156 K · 883 °C
- Electronegativity
- 0.93
- Density
- 0.968 g/cm³
Photograph — The original uploader was Dnn87 at English Wikipedia., CC BY-SA 3.0 <https://creativecommons.org/licenses/by-sa/3.0>, via Wikimedia Commons
Emission spectrum
The visible light Sodium emits when energised — its unique spectral fingerprint.
Identity
- Atomic number
- 11
- Standard atomic weight
- 22.99 u
- Category
- Alkali metal
- Group
- 1 · Alkali metals
- Period
- 3
- Block
- s-block
- Oxidation states
- +1
Physical properties
- Melting point
- 371 K · 98 °C
- Boiling point
- 1156 K · 883 °C
- Density
- 0.968 g/cm³
- Molar heat capacity
- 28.23 J/(mol·K)
- Atomic radius
- 227 pm
- Electron affinity
- 52.867 kJ/mol
Atomic structure
11protons
12neutrons
11electrons
1valence e⁻
- Noble-gas notation
- [Ne] 3s1
- Full configuration
- 1s2 2s2 2p6 3s1
- Electrons per shell
- 2, 8, 1
Periodic trends
Where Sodium ranks across all 118 elements.
Ionization energies
Energy to remove each successive electron (kJ/mol).
495.81
4.6k2
6.9k3
9.5k4
13.4k5
16.6k6
20.1k7
25.5k8
28.9k9
141.4k10
Successive ionization energies (kJ/mol, log scale).
Discovery
- Discovered
- 1807
- Discovered by
- Humphry Davy
- Named by
- —
- Appearance
- silvery white metallic