Neutrons are the particles in an atom that have a neutral charge. Protons and electrons are other particles found in an atom. Protons have a positive charge and neutrons have a negative one.
Neutrons are found in the nucleus of an atom, and protons are usually found with them. Neutron numbers determine the mass of the atom, because they weigh almost the same as a proton and electron combined. All elements on the periodic table have atoms with neutrons except for hydrogen. A normal hydrogen atom does not have any neutrons in its nucleus. Neutrons also play a role in the radioactive properties of atoms. Changing the normal number of neutrons in an atom creates an isotope.