Recognised as Chemical element
Sodium
- Na
- Z = 11
- alkali metal
Sodium (Na) is element 11, an alkali metal in period 3 and group 1. Its standard atomic weight is 22.99 Da. Weights follow IUPAC standard atomic weights, 2021 revision.
Identity
SymbolNa
Standard atomic weight22.99atomic mass units (Da)
Mass in kilograms3.8175793 × 10^-26
Categoryalkali metal
Group1
Period3
Blocks-block
Electrons in a neutral atom11
Neutrons in the most common isotope12≈
Electron configuration
Configuration1s² 2s² 2p⁶ 3s¹ground state, subshells written in order of n
Noble gas shorthand[Ne] 3s¹
Electrons per shell2, 8, 1K, L, M and outward
Electrons in the outer shell1
Unpaired electrons1Hund's rule; unpaired electrons make the free atom paramagnetic
Madelung ruleFollowedthe ground state is what the n + l filling order predicts
Quantities
Molar mass22.99 g/mol
Mass of one mole22.99 grams
Atoms in one gram2.619461 × 10^22
Mass of one atom3.8175793 × 10^-23 g
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