**Fusion and Fission of different atoms have different energy responses** Basically, if an atom has a low atomic number, combing them (doing [[Nuclear Fusion]]) releases more energy than it takes. You're overcoming the strong force. If an atom has a high atomic number, they have a lot of energy already stored inside them. Hitting them with a particle release more energy than it takes. You're overcoming the weak force. Apparently Fe (iron) is the [[Critical Point]] in the fusion/fission curve, where Fusion begins _taking_ energy and Fission begins _releasing_ releasing energy.  **** # More ## Source - [Stack Exchange](https://physics.stackexchange.com/questions/457686/why-do-fusion-and-fission-both-release-energy) ## Related - [[Nuclear Fusion]]