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Sodium

Element 11 · Alkali metal

Specimen

Atomic number
11
Atomic mass
22.99
State at room temperature
Solid
Melting point
97.8 °C
Boiling point
882.9 °C
Density
0.97 g/cm³
Discovered
1807

Atomic mass from IUPAC.1 Other physical data from PubChem.2

Can I eat it?

In food and water
Your body needs it. As sodium chloride (table salt), sodium is an essential nutrient. WHO recommends that adults eat less than 2000 mg of sodium a day. That is less than 5 g of salt. 3

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The atom

Na
ShellElectrons
1 (K) 2
2 (L) 8
3 (M) outermost 1
Total11

Configuration [Ne] 3s¹

3s ↑
A shell diagram: each ring is an electron shell and each dot is one electron. The nucleus holds 11 protons. The outermost shell is shown in red. Electrons do not travel on rings: they fill orbitals, regions where an electron is likely to be found. The boxes are those orbitals for the electrons outside the Ne core, with one arrow per electron.

Related elements

Group 1
H Hydrogen Li Lithium K Potassium Rb Rubidium Cs Caesium Fr Francium

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Sources

  1. 1

    IUPAC Commission on Isotopic Abundances and Atomic Weights (CIAAW), 2024. Abridged Standard Atomic Weights 2024 .

    The atomic mass shown for the 84 elements that have a standard atomic weight.

  2. 2

    National Center for Biotechnology Information (PubChem), 2026. Periodic Table of Elements .

    Electron configuration, melting and boiling points, density and discovery year for all 118 elements.

  3. 3

    World Health Organization, 2025. Sodium reduction (fact sheet) .

    • Sodium is an essential nutrient necessary for the maintenance of plasma volume, acid-base balance, transmission of nerve impulses and normal cell function.
    • For adults, WHO recommends less than 2000 mg/day of sodium (equivalent to less than 5 g/day salt)
  4. 4

    National Institute of Standards and Technology (NIST), 2026. Atomic Weights and Isotopic Compositions for All Elements .

    Isotopic composition of each element; the most abundant isotope sets the neutron count in the nucleus view.