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9Sci CH24
9th Science CH24 Radioactivity and Nuclear Reactions
Term | Definition |
---|---|
alpha particle | a particle of nuclear radiation emitted from a decaying atomic nucleus; has a charge of 2+, an atomic mass of 4, and is the largest, slowest, and least penetrating form of radiation |
beta particle | a negatively charged electron or positively charged positron emitted from a decaying atomic nucleus; beta particles are faster moving and more penetrating than alpha particles |
bubble chamber | device filled with super-heated liquid; used to detect and monitor the path of charged nuclear particles, which leave a trail of bubbles as they pass through the chamber |
chain reaction | a continuing series of fission reactions in which neutrons from fissioning nuclei cause other nuclei to split, releasing more neutrons, which split more nuclei, and so on |
cloud chamber | device filled with water- or ethanol- saturated air; used to detect charged nuclear particles which leave a trail as they pass through |
gamma ray | high-frequency electromagnetic waves that travel at the speed of light, have no mass or charge, and are the most penetrating form of radiation |
half-life | the amount of time required for one-half of the nuclides in a sample of radioactive isotope to decay |
nuclear fission | process in which an atom’s nucleus is split into two nuclei with smaller masses |
nuclear fusion | process in which two atomic nuclei with low masses are fused into a single nucleus of larger mass; also known as a thermonuclear reaction |
nuclide | the nucleus of a specific isotope having a certain specific atomic number and atomic mass |
PET | Positron-Emission Tomography; PET scans are used in medicine to reveal brain function and certain brain disorders such as tumors |
radioactivity | the emission of high-energy radiation or particles from the nucleus of a radioactive atom |
tracer | a radioisotope used in medical diagnosis to allow doctors to monitor human body functions, locate tumors, detect fluid movement, and so on |
transmutation | changing one element to another through radioactive decay |