is this just a mass problem? and how do you "solve" this?
in beta minus decay a neutron turns into a proton and an electron (which is emmited) so final mass is (allways?) bigger or equal to original mass, since inside the nucleus mass stays the same, plus an electron added to the atom (which is not the emmited one, correct?). So it appears to me this is allways possible.
in beta plus a proton turns into a neutron plus an emmited positron, and so final mass is lower than orignal due to an electron loss to keep things balanced. so it appears to me that this is never possible(???)
what happens in EC? an electron is captured by the nucleus and a neutrino is emmited, why is the final atomic number lower?
so how do you figure out if any of this processes are possible for a given decay?