Atom, Ion, or Isotope? Atoms Atoms are neutral Protons = Electrons There are special kinds of atoms.... Ions Isotopes Ions An Ion is an atom that has gained or lost ELECTRONS, so it has an overall charge If an atom gains electrons, it’s overall charge becomes negative. If an atom loses electrons, it’s overall charge becomes positive. If an atom gains/loses electrons, its mass will not change. Isotopes An Isotope is an atom that has gained or lost NEUTRONS If an atom gains/loses neutrons, charge is not affected. If an atom gains neutrons, its mass will increase. If an atom loses neutrons, its mass will decrease. Atomic Number Because atoms can gain or lose electrons and neutrons to become ions or isotopes, the atomic number will ALWAYS identify the number of PROTONS an atoms has.