Heavy, less stable nuclei like Uranium-235 split into smaller fragments. These fragments are closer to the iron peak, meaning they have higher binding energy and release the "missing" energy during the split. Stellar Nucleosynthesis
. Nuclei in this "iron peak" (notably and Nickel-62 ) are the most tightly bound and stable in the universe. The curve of binding energy
For very light elements like Hydrogen, the binding energy is low but increases sharply as mass number increases. This steep gradient explains why nuclear fusion (combining light nuclei) releases a massive amount of energy. Heavy, less stable nuclei like Uranium-235 split into
), indicating that nuclear forces are "saturated" in mid-sized nuclei. The curve of binding energy