Potassium
A reactive metal essential to nerve and muscle function.
Inside the Potassium atom
Switch between Bohr and Quantum Cloud modes to compare a simple teaching model with a more realistic probability-based view, and follow the guided tour to explore the Potassium atom step by step.
Electron configuration
[Ar] 4s1
A neutral Potassium atom has 19 electrons (equal to its proton count). Choosing a different isotope above changes only the neutron count.
Shell distribution
Electrons fill inner shells before outer ones; the outermost (valence) shell drives the element's chemistry.
Physical & atomic properties
- State (room temp)
- Solid
- Melting point
- 337 K (63 °C)
- Boiling point
- 1032 K (759 °C)
- Density
- 0.862 g/cm³
- Electronegativity
- 0.82 Pauling
- Atomic radius
- 220 pm
- 1st ionization energy
- 419 kJ/mol
- Category
- Alkali metals
Discovery & naming
- Discovered
- 1807
- Discovered by
- Humphry Davy
- Origin of name
- English 'potash'; symbol from Latin 'kalium'.
Notable uses
Fertilizers, salt substitutes, and nerve and muscle function.
Where Potassium comes from
Stellar fusion and dying stars
A modest product of oxygen burning in massive stars and of explosive burning.
Simplified origin map — many elements form through more than one astrophysical pathway.
Summary
- Atomic number
- 19
- Atomic mass
- 39.098
- Category
- Alkali metals
- Group · Period
- 1 · 4
- Block
- s-block
- Shells
- 2 · 8 · 8 · 1