Electron capture leads to a decrease of one in the charge on the nucleus.
Half life and radioactive dating
The mass defect of an atom reflects the stability of the nucleus.
It is equal to the energy released when the nucleus is formed from its protons and neutrons.
The reaction is usually accompanied by the ejection of one or more neutrons.
In 1934 Enrico Fermi proposed a theory that explained the three forms of beta decay.
The product of this reaction can be predicted, once again, by assuming that mass and charge are conserved. They rapidly lose their kinetic energy as they pass through matter.