what is the source of energy in fusion and fission reactions

The source of energy in both fusion and fission reactions is the energy harnessed in the nuclei of atoms/Nuclear_Chemistry/Fission_and_Fusion/Fission_and_Fusion). Fission is the splitting of a heavy nucleus into lighter nuclei, which releases a large amount of energy in the form of heat and radiation. Uranium and plutonium are commonly used for fission reactions in nuclear power reactors because they are easy to initiate and control. On the other hand, fusion is the combining of nuclei to form a bigger and heavier nucleus, which releases even more energy than fission. Fusion is the source of energy in the sun and stars. However, forcing light hydrogen-like nuclei together to create fusion reactions requires very high temperatures, which is why fusion is still in the research and development phase.