Stable isotope Potassium (K)

Isotope Z(p) N(n) Atomic Mass Natural Abundance Enrichment Level Chemical Form
K-39 19 20 38.9637069 93.26% >99.90% Chloride
K-40 19 21 39.9639985 0.01% 5.00-16.95% Chloride
K-41 19 22 40.9618260 6.73% >95.00% Chloride

Properties of Potassium

Name Potassium
Symbol K
Atomic number 19
Atomic weight 39.098
Standard state Solid at 298 °K
CAS Registry ID 7440-09-7
Group in periodic table 1
Group name Alkali metal
Period in periodic table 4
Block in periodic table s-block
Color Silvery white
Classification Metallic
Melting point 63.25 °C
Boiling point 760 °C
Thermal conductivity 102.5 W/(m·K) at 298.2 °K
Electrical resistivity 6.1 µΩ·cm at 0 °C
Electronegativity 0.8
Specific heat 0.75 kJ/kg K
Heat of vaporization 76.9 kJ·mol-1 at 760 °C
Heat of fusion 2.33 kJ·mol-1
Density of liquid 0.819 g/cm3 at 100 ºC and 0.771 g/cm3 at 300 ºC
Density of solid 0.862 g/cm3 at 20 ºC
Electron configuration [Ar]4s
Atomic radius 2.35 Å
Oxidation state +1
Ionization potential 4.341 eV