| A | B |
|---|
| Atomic number | The number of protons in the nucleus |
| Atomic mass number | The number of protons plus the number of neutrons in a nucleus |
| Isotope | Atoms with the same atomic number, having a different number of neutroms |
| Atomic spectrum | An element's fingerprint |
| Photon | A quantum of light |
| Periods | The horizontal rows on the periodic table |
| Atomic mass | The usual units are "amu" |
| Groups | The vertical columns on the periodic table |
| Electron | Negative charge |
| Proton | Positive charge |
| Neutron | Zero charge |
| Alpha particle | Charge of +2 |
| Beta particle | Charge of -1 |
| Gamma ray | High energy E&M radiation |
