I've always struggled with the concept of fission and fusion. I mean I can show a mass deficit with math easily enough but I have always struggled understanding the fundamental concept of why things are the way they are....maybe someone can help me find the error in my reasoning. Please no math or B/E charts in your explanations!
As we build a nucleus, you have to overcome electrostatic repulsion between protons, but after you get them close enough they bond because of the nuclear strong force (neutrons don't have this problem). Free floating nucleons are higher energy than bound nucleons just like a ball in the air is higher energy than a ball on the ground, so once bonding happens the nucleus sheds the excess energy IAW conservation of energy and the lower energy state is reflected as a mass deficit.
As we continue to grow the atom the nuclear force increases at first because more immediate nucleon neighbors, however eventually the nucleus gets too fat and the effects of the strong force for each additional nucleon diminished due to range while the repulsion is essentially unaffected. Eventually the largest atoms are made and are unstable because the strong force more or less perfectly balances out the electrostatic repulsion.
As the atoms vibrate they change shape slightly and parts fly off because they are so close to exploding (natural radiation).
So that explains why fusion releases energy and why there is a max atom size. What it doesn't explain is why after iron fission releases energy and fusion requires energy.
It seems to me like a smaller "unbound" particle should always release energy when bound and saying that after Nickel-56 fusion requires energy seems like a reversal of physics (obviously its not but I don't understand why).
At one point I thought I had it all figured out. I reasoned that fusion is an infinite potential well due to the strong force which is much stronger than the electrostatic forces. Fission was not the result of binding energy but actually just the result of the electrostatic repulsion releasing i.e. fission and fusion really have two different sources where one is nuclear strong force from binding and one is electrostatic tension being released due to deformation. Is that accurate?