| A | B |
|---|
| sum of the number of protons and the number of neutrons in the nucleus of an atom | mass number |
| positively charged subatomic particle | proton |
| dense, positively charged center of atom | nucleus |
| subatomic particle with zero charge | neutron |
| atoms with same number of protons but different numbers of neutrons | isotopes |
| negatively charged ion | anion |
| number of protons in the nucleus of an atom | atomic number |
| atom with a charge | ion |
| positively charged ion | cation |
| negatively charged subatomic particle | electron |
