1. Atomic Mass - protons + neutrons in the nucleus of an atom
2. Neutron - the neutrally charged element in the nucleus of an atom
3. Atomic Number - the number of protons an atom has
4. Proton - the positive particle in the nucleus of an atom
5. Isotope - an atom of an element that has a different number of neutrons that the standard atom of that element
Hope This Helps!