| 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 |
| Groups | The vertical columns on the periodic table |
| Electron | Negatively charged particle |
| Proton | Positively charged particle |
| Neutron | has no charge |
| Alpha particle | A helium nucleus |
| Beta particle | Has the mass and charge of an electron |
| Gamma ray | High energy E&M radiation |
| Half-life | A measurement of the rate of decay of a radioactive element |
| Fusion | Two atoms bind together and energy is released |
| Fission | The nucleus splits into one or more particles and energy is released |
