Element 11 · Alkali metal
Sodium (Na) — Element 11
English soda
Sodium (Na) is an alkali metal in Period 3, Group 1 of the periodic table with atomic number 11, standard atomic weight 22.990 u, and ground-state electron configuration [Ne] 3s¹. At standard temperature and pressure it is classified as a solid with 1 valence electron and common oxidation states +1.
Table salt, street lamps, soap
What are the atomic properties and physical constants of Sodium?
Reference constants compiled from IUPAC standard atomic weights, the NIST Atomic Spectra Database, and the CRC Handbook.
- Atomic number (Z)
- 11
- Standard atomic mass
- 22.990 u
- Chemical family
- Alkali metal
- Ground-state configuration
- [Ne] 3s¹
- Electrons per shell
- 2, 8, 1
- Valence electrons
- 1
- Common ion charges / oxidation states
- +1
- Phase at STP
- Solid
- Pauling electronegativity
- 0.93 Pauling
- First ionization energy
- 496 kJ/mol
- Atomic radius
- 190 pm
- Melting point
- 98 °C
- Boiling point
- 883 °C
- Discovery year
- 1807
- Table coordinate
- Period 3, Group 1
- Radioactivity
- Has stable isotope(s)
How are electrons arranged across Sodium’s shells?
A neutral Sodium atom contains 11 electrons distributed across 3 occupied principal energy shells ([Ne] 3s¹). The table below compares Sodium’s shell occupancy against each shell’s theoretical 2n² capacity.
| Principal Shell (n) | Spectroscopic Letter | Electrons in Na | Max Shell Capacity (2n²) |
|---|---|---|---|
| n = 1 | K | 2 e⁻ | 2 e⁻ |
| n = 2 | L | 8 e⁻ | 8 e⁻ |
| n = 3 | M | 1 e⁻ | 18 e⁻ |
Frequently Asked Questions about Sodium (Na)
What is the atomic mass and atomic number of Sodium (Na)?
Sodium (Na) has atomic number Z = 11 (11 protons in its nucleus) and an IUPAC standard atomic weight of 22.990 u. It sits in Period 3, Group 1 and is classified as an alkali metal.
What is the ground-state electron configuration of Sodium?
The neutral ground-state electron configuration of Sodium (Z = 11) is [Ne] 3s¹. Across its 3 occupied principal shells (n = 1 to n = 3), the electrons per shell are 2, 8, 1, with 1 valence electron participating in bonding.
What are the common ion charges and electronegativity of Sodium?
Sodium commonly forms +1 oxidation states or ion charges in compounds. Its Pauling electronegativity is 0.93 and its first ionization energy is 496 kJ/mol.
When was Sodium discovered and what is it used for?
Sodium was discovered in 1807 (English soda). Table salt, street lamps, soap
How does Sodium compare to neighboring elements?
Other alkali metal elements: