Go to 6:06 From what I've read, it appears that binding energy is the mass lost equally from each nucleon in a nucleus and it is used as some sort of 'glue' in the strong nuclear force to hold the nucleus together. I'm guessing that is incorrect because, with that logic, 2mev + 10mev nuclei fusing to a nucleus that requires 28 mev looks like it would need energy. That also makes sense because larger nuclei have more electrostatic repulsion from protons and so would need more binding energy per nucleon to overcome that foce (or does that never change? is the binding energy per nucleon always the same, and what increases is the total binding energy due to more nucleons, so when an atom is unstable it is simply because the electrostatic repulsion have over come the strong nuclear force, instead of the strong nuclear force not being able to increase any more per nucleon?) As such, it appears that binding energy is just how much energy 'needs to be lost' per nucleon. That way, the 28MEV in the video means that 28-10=18mev needs to be lost for the atom to hold itself together. Could someone please explain that further to me? Thank you in advance.