Recognised as Chemical element
Potassium
- K
- Z = 19
- alkali metal
Potassium (K) is element 19, an alkali metal in period 4 and group 1. Its standard atomic weight is 39.098 Da. Weights follow IUPAC standard atomic weights, 2021 revision.
Identity
SymbolK
Standard atomic weight39.098atomic mass units (Da)
Mass in kilograms6.4923756 × 10^-26
Categoryalkali metal
Group1
Period4
Blocks-block
Electrons in a neutral atom19
Neutrons in the most common isotope20≈
Electron configuration
Configuration1s² 2s² 2p⁶ 3s² 3p⁶ 4s¹ground state, subshells written in order of n
Noble gas shorthand[Ar] 4s¹
Electrons per shell2, 8, 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 mass39.098 g/mol
Mass of one mole39.098 grams
Atoms in one gram1.5402682 × 10^22
Mass of one atom6.4923756 × 10^-23 g
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