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Ch. 9 Holt
Nuclear Changes
Term | Definition |
---|---|
Radioactivity | the process by which an unstable nucleus emits one or more particles or energy in the form of electromagnetic radiation. |
Nuclear Radiation | the particles that are released from the nucleus during radioactivite decay. |
Alpha Particle | a positively charged atom that is released in the disintegration of radioactive elements and that consists of two protons and two neutrons. |
Beta Particle | a charged electron emitted during certain types of radioactive decay such as beta decay. |
Gamma Ray | the high-energy phonton emitted by a nucleus during fission and radioactive decay. |
Half-life | the time required for half of a smaple of a radioactive substance to disintegrate by radioactive decay or by natural processes. |
Fission | the process by which a nucleus splits into two or more fragments and releases neutrons and energy. |
Nuclear Chain Reaction | a continuous series of nuclear fission reactions. |
Critical Mass | the minimum mass of a fissionable isotope that provides the number of neutrons needed to sustain a chain reaction. |
Fusion | the process in which light nuclei combine at extremely high temperatures, forming heavier nuclei and releasing energy. |
Background Radiation | the nuclear radiation that arises naturally from cosmic rays and from radioactive isotopes in the soil and air. |
Rem | the quantity of ionizing radiation that does as much damaged to human tissue as 1 roentgen of high-voltage X-rays does. |
Radioactive Tracer | a radioactive material that is added to a substance so that its distribution can be detected later. |