Neutrons are part of the nucleus, or center of the atom. The neutron is an elementary particle without any electrical change.
Neutrons were discovered in 1932, by james Chadwick. The discovery of the neutron dramatically changed the picture of the atom.
The impact of the discovery was such that it completed the under-standing of the structure of both the atom, and the atomic nucleus. It also made sense of isotopes or atomic species with the same chemical properties, but different masses.
Neutrons had been shown to cause fission to cause fission of certain nuclei with a release of large amounts of energy. This had momentous consequences in the field of nuclear energy.