Energy from Fusion and Fission
Nuclear binding energy comes from both the strong force and the weak force. When two lightweight nuclei combine with one another and become one heavier nucleus, they mainly release the potential energy of the strong force, the energy of fusion. When a heavy nucleus breaks up and becomes two lighter nuclei, it usually releases the energy of the weak force, the energy of fission. Midway between lightweight and heavy nuclei is iron, the most stable element of all. The most abundant form of iron has 26 protons and 30 neutrons. It takes energy either to break up an iron nucleus or to add to it. Neither fission nor fusion releases any energy from the most abundant iron nuclei.
Of all the nuclear reactions, the ones that release the most energy per particle are fusion reactions that turn hydrogen into helium. This is what powers the Sun and most of the stars.
Of all the nuclear reactions, the ones that release the most energy per particle are fusion reactions that turn hydrogen into helium. This is what powers the Sun and most of the stars.
