The process of splitting atoms is called nuclear fission. Nuclear fission involves the splitting of an atomic nucleus into two or more smaller nuclei, accompanied by the release of a significant amount of energy. This process is typically induced by bombarding the nucleus with a neutron, which makes it unstable and causes it to split.
When a nucleus undergoes fission, it releases a large amount of energy in the form of kinetic energy of the fission fragments (the smaller nuclei), as well as the release of multiple high-energy neutrons. These released neutrons can then go on to induce fission in other nearby nuclei, leading to a self-sustaining chain reaction.
Nuclear fission is the principle behind the operation of nuclear power plants and is also used in nuclear weapons. In nuclear power plants, controlled fission reactions are used to generate heat, which is then used to produce steam and drive turbines for the generation of electricity. In nuclear weapons, uncontrolled fission reactions are harnessed to release an enormous amount of energy in the form of an explosion.