| Flap 1 | Flap 2 |
| radioactive element | elements that emit alpha, beta or gamma radiation |
| alpha particle | two protons and two neutrons or a nucleus of a helium atom |
| beta particle | an electron ejected by an atomic nucleus |
| gamma radiation | extremely energetic form of radiation with no charge and no mass |
| strong nuclear force | very strong force that holds the nucleus together |
| transmutation | when one element changes to another by emitting an alpha or beta |
| half-life | time needed for half the radioactive atoms to decay |
| fission | splitting of atomic nucleus into parts; releases energy |
| chain reaction | occurs when the product of the reaction starts another reaction |
| fusion | small nuclei fuse together producing energy |
