| A | B |
|---|
| radioactivity | the process in which an unstable atomic nucleus emits charged particles and energy |
| radioisotope | an isotope with an unstable nucleus |
| nuclear radiation | charged particles and electromagnetic waves that are emitted from the nuclei of radioisotopes |
| alpha particle | a positively charged particle, emitted by certain radioactive nuclei, made up of two protons and two neutrons; a helium nucleus |
| beta particle | an electron emitted by an unstable nucleus |
| gamma ray | a penetrating form of radiation emitted by an unstable nucleus |
| background radiation | nuclear radiation that occurs naturally in the environment |
| half-life | the time required for one-half of a sample of a radioactive isotope to decay |
| strong nuclear force | the powerful attractive force that binds protons and neutrons together in the nucleus |
| fission | a nuclear reaction in which an atomic nucleus is split into smaller parts |
| chain reaction | a series of fission reactions triggered by neutrons released during the fission of a nucleus |
| critical mass | the smallest possible mass of a fissionable material that can sustain a chain reaction |
| fusion | a nuclear reaction in which the nuclei of two atoms combine to form a larger nucleus |
| plasma | a state of matter in which atoms have been stripped of their electrons |
