The radioactive isotope of potassium in ancient rocks decays into argon gas which becomes trapped in the rocks.
This occurs as a result of electron capture when an inner shell electron is captured by the nucleus.
A proton turns into a neutron and a neutrino is emitted.
Potassium also decays by beta emission into calcium-40 isotope. The probability of beta minus decay is 8 times greater than the probability of electron capture.
The age of the rock from the time the rock solidified can be calculated from the effective half-life of potassium-40 which is 1250 million years.
This occurs as a result of electron capture when an inner shell electron is captured by the nucleus.
A proton turns into a neutron and a neutrino is emitted.
Potassium also decays by beta emission into calcium-40 isotope. The probability of beta minus decay is 8 times greater than the probability of electron capture.
The age of the rock from the time the rock solidified can be calculated from the effective half-life of potassium-40 which is 1250 million years.