Nuclear chemistry is the sub-field of chemistry dealing with radioactivity, nuclear processes, and transformations in the nuclei of atoms, such as nuclear transmutation and nuclear properties.They are also used to help determine the mechanisms of chemical reactions, to trace the movement of atoms in biological systems, and to date important historical artifacts. Nuclear reactions are used both to generate electricity and to create weapons of massive destruction.Nuclear fusion: reactions in which two or more elements "fuse" together to form one larger element, releasing energy in the process. A good example is the fusion of two "heavy" isotopes of hydrogen (deuterium: H2 and tritium: H3) into the element helium.Chemistry is primarily concerned with things at the atomic or molecular level. Nuclear physics is concerned with the nucleus itself. There is a whole branch of chemistry called "nuclear chemistry", and what they do is essentially identical to what nuclear physicists do.