Large atoms split in nuclear fission.
Binding energy is the energy required to remove a particle from an atom. Each part of an atom has binding energy, but the term is commonly used to refer to the energy needed to split an atom’s nucleus. This energy is an integral part of discussions on nuclear fission and fusion. The binding energy of electrons is more commonly called the ionization energy.
The energy in nuclear bonds can be observed by measuring the mass of an atom, which is less than the sum of the mass of its components. This is because part of the mass of nuclear particles is converted into energy according to the equation E = mc 2 . The missing mass is the source of the binding energy. The smallest atoms have the lowest nuclear binding energy. It tends to increase with atomic number up to iron, which has the highest binding energy; larger atoms are more unstable.
Researchers are currently investigating nuclear fusion, the same method of generating energy that the sun uses.
Nuclei are made of protons and neutrons. Similar charges repel each other. Protons have a positive charge and neutrons, which are neutral, do not provide an equilibrium negative charge. The bonds in the nucleus must be strong enough to overcome the repelling forces of the positive charges on the protons. Consequently, there is a lot of energy stored in these bonds.
The processes of nuclear fission and fusion depend on the release of nuclear binding energy. In fusion, deuterium, a hydrogen atom with one neutron, and tritium, a hydrogen atom with two neutrons, come together to form a helium atom and a spare neutron. The reaction releases energy equal to the difference between the binding energy before and after the fusion. In fission, a large atom, such as uranium, splits into smaller atoms. The decaying nucleus releases neutron radiation and large amounts of energy from changing the strength of nuclear bonds in the new atoms.
The ionization energy of an electron varies based on the type of atom it is being separated from and the number of electrons that have been removed from that atom earlier. Removing outer electrons requires less energy than removing inner ones, and more energy is needed to split a pair than to remove a lone electron. The difference in ionization energies is why some configurations are more stable than others: the higher the next ionization energy, the more stable the state of the atom. Stable compounds dominate in nature; ionization energies literally shape the world.