Chemical element · Atomic number 11
Sodium
Sodium in the periodic table: atomic number 11, electron configuration, atomic mass, physical data, oxidation states, media credit and visible sources.
Alkali metal
solid
22.9897693 u
Documented element sampleA documented sample of elemental sodium; the reactive metal is stored under protection.
Image credit: James St. John
Auto-oriented, limited to 1600 × 1200 pixels and re-encoded as WebP; the subject was not altered.
Atomic classification
Shell occupancy
Sodium in the Bohr shell model
This shows the electron distribution of the neutral atom in a simplified shell model.
- K · n=1
- 2 electrons
- L · n=2
- 8 electrons
- M · n=3
- 1 electron
- Electron configuration
- [Ne]3s1
- Electrons per shell
- 2 · 8 · 1
- Group
- 1
- Period
- 3
- Block
- S
- Element category
- Alkali metal
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Physical and chemical properties
- Atomic mass
- 22.9897693 u
- Standard state
- solid
- Density
- 0.97 g/cm³
- Melting point
- 370.95 K
- Boiling point
- 1,156 K
- Electronegativity
- 0.93 (Pauling)
- First ionisation energy
- 5.139 eV
- Oxidation states
- +1
- Discovery
- 1807
Safety and periodic classification
Safety
Safe handling cannot be inferred from Sodium's position in the periodic table alone. Laboratory, classroom and disposal decisions must follow the documentation for the exact material and its safety data sheet.
Position and comparison
Sodium is in period 3, group 1 and the S block. Its direct neighbours by atomic number are Neon and Magnesium. The recorded Pauling electronegativity is 0.93. Periodic trends are compared only through the separately sourced neighbouring values.
Sources and scope
PubChem attributes element data to sources including IUPAC, NIST and IAEA. Quanta stores the referenced snapshot locally and leaves unknown values unavailable.