Hi, I was reading the wiki article here on beta decay and energy release: https://en.wikipedia.org/wiki/Beta_decay#Energy_release In obtaining a condition on the masses of the initial and final atoms we neglected the difference in electron binding energies of the two atoms. Does this mean we compare the electron binding energies of one atom to the binding energies of the other and say the difference between the two is negligible? The article says this is small for high Z atoms, which I don't understand really understand? Later, in the section on electron capture, the article goes on to say we can no longer neglect the electron binding energy for the captured electron, which again I don't fully understand. Sorry if I wasn't clear: I hope someone more knowledgable than me can help!