Question

If you add a neutron to an atom how does the properties of the atom change, the atoms identity? the atoms charge? the atoms size?

Answer 1

Neutrons do not carry an electrical charge so adding or removing them from the nucleus does not change the electrical charge of the nucleus. ... So, adding or removing protons from the nucleus changes what element that atom is! For example, adding a proton to the nucleus of an atom of hydrogen creates an atom of helium.