Isotopes of Potassium

Notable Isotopes

39K [20 neutrons]

Abundance: 93.26%

Stable with 20 neutrons

40K [21 neutrons]

Abundance: 0.012%

Half life: 1.277 x 109 years [ beta- ]

Decay Energy: 1.311 MeV

Decays to 40Ca.

Half life: 1.277 x 109 years [ Electron Capture ]

Decay Energy: 1.505 MeV

Decays to 40Ar.

Half life: 1.277 x 109 years [ beta+ ]

Decay Energy: 1.505 MeV

Decays to 40Ar.

In healthy animals and people, 40K represents the largest source of radioactivity, greater even then 14C. In a human body of 70 kg mass, about 170,000 nuclei of 40K decay per second.

41K [22 neutrons]

Abundance: 6.73%

Stable with 22 neutrons