| A | B |
|---|
| nonmetal | An element that lacks most of the properties of a metal. |
| diatomic molecule | A molecule consisting of two atoms |
| halogen | An element found in Group 17 of the periodic table. |
| inert gas | An element found in Group 18 of the periodic table. |
| semimetal | An element that has some characteristics of both metals and nonmetals. |
| semiconductor | A material that conducts current under certain conditions. |
| radioactive decay | The process in which the atomic nuclei of unstable isotopes release fast-moving particles and energy. |
| radioactivity | The ability of a substance to spontaneously emit radiation. |
| alpha particle | A type of nuclear radiation consisting of two protons and two neutrons. |
| beta particle | A fast-moving electron that is given off as nuclear radiation. |
| gamma radiation | A type of nuclear radiation made of high-energy waves. |
| tracer | A radioactive isotope that can be followed through the steps of a chemical reaction or industrial process. |
