Element 19
Potassium (K)
Potassium (K) is element 19 of the periodic table, an alkali metal in period 4, group 1 (s-block) with an atomic mass of 39.098 and is a solid at standard conditions.
At a glance
- Atomic number
- 19
- Symbol
- K
- Atomic mass
- 39.098 u
- Category
- Alkali metals
- Period
- 4
- Group
- 1
- Block
- s-block
- Phase at STP
- solid
Electron structure
- Electron configuration
- 1s2 2s2 2p6 3s2 3p6 4s1
- Shorthand configuration
- [Ar] 4s1
- Electrons per shell
- 2, 8, 8, 1
- Oxidation states
- -1, +1
Physical properties
- Melting point
- 336.53 K (63.38 °C)
- Boiling point
- 1,032 K (758.85 °C)
- Density
- 0.862 g/cm³
- Phase
- solid
Atomic properties
- Electronegativity (Pauling)
- 0.82
- Atomic radius
- 243 pm
- Covalent radius
- 203 pm
- Van der Waals radius
- 275 pm
- First ionization energy
- 419 kJ/mol
- Electron affinity
- 48 kJ/mol
Notable isotopes
| Isotope | Mass | Abundance | Stability |
|---|---|---|---|
| K-39 | 38.96371 | 93.26% | Stable |
Common uses
- Fertilizers
- Soap making
- Gunpowder
- Heart function
Discovery
- Year
- 1807
- Discovered by
- Humphry Davy
- Country
- England
Frequently asked questions
- Is potassium a metal?
- Yes. Potassium is a metal, classified as an alkali metal on the periodic table.
- How many protons does potassium have?
- Potassium has 19 protons. Its atomic number is 19, which is also the number of electrons in a neutral atom of potassium.
- What group and period is potassium in?
- Potassium is in group 1 and period 4 of the periodic table, in the s-block.
- What is the atomic mass of potassium?
- The atomic mass of potassium is 39.098 u (unified atomic mass units).
Keep exploring
Potassium's row is on the printable element property sheet, and its tile is on the periodic table wall chart - the same numbers as above, laid out for A4 or A3 paper.