SymbolK
Latin nameKalium
Atomic number19
Period4
Element categoryAlkali metals
Relative atomic mass39.0983
GroupI.A
Electronegativity
0.9
Oxidation numbers
1
Electron configuration
1s2 2s2 2p6 3s2 3p6 4s1
Density [g/cm3]
0.862
State
Solid
Melting point [°C]
93.65
Boiling point [°C]
760
Critical point [°C]
1950
Critical pressure [MPa]
16
Atomic radius [pm]
243
Covalent radius [pm]
196
Thermal conductivity [W m-1K-1]
102.5
Heat capacity [J K-1g-1]
0.757
Discovery
1807
Hardness [Mohs scale]
0.5
Brinell hardness [MPa]
0.363
Electrical conductivity [S m-1]
1.64 · 107
1.st ionization energy [eV]
4.3407
2.nd ionization energy [eV]
31.625
3.rd ionization energy [eV]
45.72
Stable isotopes
3
Unstable isotopes
8