where m N ( X Z A ) is the mass of the nucleus of the Z X atom, m e is the mass of the electron, and m ν ν ¯ ¯ e is the mass of the electron antineutrino. In other words, the total energy released is the mass energy of the initial nucleus, minus the mass energy of the final nucleus, electron, and antineutrino. The mass of the nucleus m N is related to the standard atomic mass m by m ( X Z A ) c 2 = m N ( X Z A ) c 2 + Z m e c 2 − − ∑ ∑ i = 1 Z B i . That is, the total atomic mass is the mass of the nucleus, plus the mass of the electrons, minus the sum of all electron binding energies B i for the atom. This equation is rearranged to find m N ( X Z A ) , and m N ( X Z + 1 A ′ ) is found similarly. Substituting these nuclear masses into the Q -value equation, while neglecting the nearly-zero antineutrino mass and the difference in electron binding energies, which is very small for high- Z atoms, we have Q = [ m ( X Z A ) − − m ( X Z + 1 A ′ ) ] c 2 This energy is carried away as kinetic energy by the electron and antineutrino.