Sodium (Na)
Alkali metal
Sodium is a soft, silvery alkali metal that reacts vigorously with water — yet its compounds are everywhere in daily life, from table salt to baking soda. Sodium ions are vital for nerves and muscles.
Position on the periodic table
Atomic properties
| Atomic number | 11 |
|---|---|
| Atomic mass | 22.9898 amu |
| Electron configuration | 1s2 2s2 2p6 3s1 |
| Noble gas shorthand | [Ne] 3s1 |
| Electrons per shell | 2, 8, 1 |
| Valence electrons (outer shell) | 1 |
| Common oxidation states | +1 |
| Electronegativity (Pauling) | 0.93 |
| Covalent radius (approx.) | 166 pm |
| First ionization energy | 495.8 kJ/mol |
| Electron affinity | 52.9 kJ/mol |
Physical properties
| State at 25 °C | Solid |
|---|---|
| Density | 0.968 g/cm³ |
| Melting point | 97.79 °C (370.94 K) |
| Boiling point | 882.94 °C (1156.1 K) |
| Appearance | silvery white metallic |
| Radioactive | No |
| Origin | Occurs naturally |
Electron configuration of sodium
Sodium's ground-state electron configuration is 1s2 2s2 2p6 3s1, usually shortened to [Ne] 3s1. Its electrons occupy 3 shells (2, 8, 1), placing it in period 3 of the s-block. The 1 outer-shell electron drives its bonding behaviour. Explore it interactively in the electron configuration calculator.
Uses of sodium
- Table salt (sodium chloride) and food preservation
- Street lights (sodium-vapour lamps give an orange glow)
- Making soaps, glass and paper (via NaOH and Na₂CO₃)
- Coolant in some nuclear reactors (liquid sodium)
Biological role: Essential — sodium ions carry nerve impulses and regulate body fluids.
Occurrence: About 2.4% of the Earth's crust; vast amounts dissolved in seawater.
Common compounds of sodium
NaCl
Sodium chloride (table salt)
NaOH
Sodium hydroxide
NaHCO3
Baking soda
Na2CO3
Washing soda
History and discovery
Discovered: 1807 — Humphry Davy. Name origin: From English soda; the symbol Na comes from Latin natrium.
Humphry Davy isolated sodium in 1807 by passing electricity through molten sodium hydroxide.
Safety notes
Sodium metal reacts violently with water and is stored under oil. Its everyday compounds, like salt, are safe in normal amounts.
Educational context only — always follow your school's laboratory rules and never handle chemicals without proper supervision. See our disclaimer.
Practice questions
Quick practice: Sodium
1. What is the chemical symbol of Sodium?
2. What is the atomic number of Sodium?
3. Which category does Sodium belong to?
4. What is the state of Sodium at room temperature?
5. Which period of the periodic table is Sodium in?
Sodium FAQs
Is Na (sodium) a metal?
Yes. Sodium — symbol Na, from the Latin natrium — is a soft, silvery alkali metal in group 1. It is so reactive that it is stored under oil and reacts vigorously with water.
What is the atomic number of sodium?
Sodium's atomic number is 11 — every sodium atom has 11 protons in its nucleus.
What is the symbol for sodium?
Na. From English soda; the symbol Na comes from Latin natrium.
Is sodium a metal, nonmetal, or metalloid?
Sodium is classified as a alkali metal.
What state is sodium at room temperature?
At about 25 °C, sodium is a solid. It melts at 97.79 °C.
How many valence electrons does sodium have?
Sodium has 1 electron in its outer shell (shell pattern: 2, 8, 1).
What is sodium used for?
Key uses include: table salt (sodium chloride) and food preservation; street lights (sodium-vapour lamps give an orange glow); making soaps, glass and paper (via naoh and na₂co₃).
Sources & references
- Sodium — Element information — Royal Society of Chemistry
Atomic masses and element data follow current IUPAC/NIST standard values. Educational content only — for graded or laboratory work, verify against your course materials. Last reviewed July 11, 2026.
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