Alpha, beta and gamma decay equations

In alpha decay, emission of a helium−4 nucleus reduces A by four and Z by two. In beta-minus decay a neutron-rich nucleus converts a neutron into a proton, electron and electron antineutrino; the daughter A stays fixed and Z increases by one. In beta-plus decay a proton-rich nucleus converts a proton into a neutron, positron and electron neutrino; A stays fixed and Z decreases by one.

Gamma emission releases nuclear excitation energy as electromagnetic radiation without changing A or Z. Write the parent and daughter numbers separately, then check charge and nucleon-number balance. The electron in beta-minus decay is created in the weak process; it is not an orbital electron expelled from a shell. Not every proposed decay is energetically allowed merely because its numbers balance.

Watch out: It converts a neutron into a proton and creates an electron and antineutrino in the decay process.