| A | B |
|---|
| nucleons | protons and neutrons in a nucleus |
| mass defect | mass lost by conversion to energy when a nucleus forms from separated nucleons |
| nuclear binding energy | energy emitted when nucleons come together |
| band of stability | area on a graph of neutron number verses proton number in which all stable nuclei lie |
| radioactivity | decay of unstable nuclei to produce alpha particles, beta particles, and gamma rays |
| beta particle | high-energy electron emitted from the nucleus when a neutron changes to a proton |
| gamma ray | high-energy electromagnetic radiation produced by decaying nuclei |
| fission | nuclear reaction in which a very heavy nucleus splits into 2 smaller nuclei of approximately equal mases |
| chain reaction | self-sustaining nuclear or chemical reaction in which the product from one step acts as a reactant for the next step |
| critical mass | smallest mass of radioactive material needed to sustain a chain reaction |
| half-life | time it takes for one half of a sample to decay |
| fusion | two light nuclei combine to make one heavire nucleus |
| alpha particle | a helium nucleus |
| mass number | # protons + # neutrons |
| atomic number | # protons |
| isotopes | atoms that have the same number of protons, but different numbers of neutrons |
| moderator | used in a nuclear reactor to slow down neutrons |
| control rods | absorb neutrons in a nuclear reactor |
| radiocarbon dating | a way to date once living objects based on the half-life of carbon--14 |
| nuclide | general term applied to each unique atom |
