21.8: Key Terms
- Page ID
- 421392
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|---|---|---|---|---|---|
| (Eg. "Genetic, Hereditary, DNA ...") | (Eg. "Relating to genes or heredity") |  | The infamous double helix | https://bio.libretexts.org/ | CC-BY-SA; Delmar Larsen |
| Word(s) | Definition | Image | Caption | Link | Source |
|---|---|---|---|---|---|
| alpha (α) decay | loss of an alpha particle during radioactive decay | ||||
| alpha particle | (α or or high-energy helium nucleus; a helium atom that has lost two electrons and contains two protons and two neutrons | ||||
| antimatter | particles with the same mass but opposite properties (such as charge) of ordinary particles | ||||
| band of stability | (also, belt of stability, zone of stability, or valley of stability) region of graph of number of protons versus number of neutrons containing stable (nonradioactive) nuclides | ||||
| becquerel (Bq) | SI unit for rate of radioactive decay; 1 Bq = 1 disintegration/s | ||||
| beta (β) decay | breakdown of a neutron into a proton, which remains in the nucleus, and an electron, which is emitted as a beta particle | ||||
| beta particle | or or high-energy electron | ||||
| binding energy per nucleon | total binding energy for the nucleus divided by the number of nucleons in the nucleus | ||||
| chain reaction | repeated fission caused when the neutrons released in fission bombard other atoms | ||||
| chemotherapy | similar to internal radiation therapy, but chemical rather than radioactive substances are introduced into the body to kill cancer cells | ||||
| containment system | (also, shield) a three-part structure of materials that protects the exterior of a nuclear fission reactor and operating personnel from the high temperatures, pressures, and radiation levels inside the reactor | ||||
| control rod | material inserted into the fuel assembly that absorbs neutrons and can be raised or lowered to adjust the rate of a fission reaction | ||||
| critical mass | amount of fissionable material that will support a self-sustaining (nuclear fission) chain reaction | ||||
| curie (Ci) | larger unit for rate of radioactive decay frequently used in medicine; 1 Ci = 3.7 1010 disintegrations/s | ||||
| daughter nuclide | nuclide produced by the radioactive decay of another nuclide; may be stable or may decay further | ||||
| electron capture | combination of a core electron with a proton to yield a neutron within the nucleus | ||||
| electron volt (eV) | measurement unit of nuclear binding energies, with 1 eV equaling the amount energy due to the moving an electron across an electric potential difference of 1 volt | ||||
| external beam radiation therapy | radiation delivered by a machine outside the body | ||||
| fissile (or fissionable) | when a material is capable of sustaining a nuclear fission reaction | ||||
| fission | splitting of a heavier nucleus into two or more lighter nuclei, usually accompanied by the conversion of mass into large amounts of energy | ||||
| fusion | combination of very light nuclei into heavier nuclei, accompanied by the conversion of mass into large amounts of energy | ||||
| fusion reactor | nuclear reactor in which fusion reactions of light nuclei are controlled | ||||
| gamma (γ) emission | decay of an excited-state nuclide accompanied by emission of a gamma ray | ||||
| gamma ray | (γ or short wavelength, high-energy electromagnetic radiation that exhibits wave-particle duality | ||||
| Geiger counter | instrument that detects and measures radiation via the ionization produced in a Geiger-Müller tube | ||||
| gray (Gy) | SI unit for measuring radiation dose; 1 Gy = 1 J absorbed/kg tissue | ||||
| half-life (t1/2) | time required for half of the atoms in a radioactive sample to decay | ||||
| internal radiation therapy | (also, brachytherapy) radiation from a radioactive substance introduced into the body to kill cancer cells | ||||
| ionizing radiation | radiation that can cause a molecule to lose an electron and form an ion | ||||
| magic number | nuclei with specific numbers of nucleons that are within the band of stability | ||||
| mass defect | difference between the mass of an atom and the summed mass of its constituent subatomic particles (or the mass “lost” when nucleons are brought together to form a nucleus) | ||||
| mass-energy equivalence equation | Albert Einstein’s relationship showing that mass and energy are equivalent | ||||
| millicurie (mCi) | larger unit for rate of radioactive decay frequently used in medicine; 1 Ci = 3.7 1010 disintegrations/s | ||||
| nonionizing radiation | radiation that speeds up the movement of atoms and molecules; it is equivalent to heating a sample, but is not energetic enough to cause the ionization of molecules | ||||
| nuclear binding energy | energy lost when an atom’s nucleons are bound together (or the energy needed to break a nucleus into its constituent protons and neutrons) | ||||
| nuclear chemistry | study of the structure of atomic nuclei and processes that change nuclear structure | ||||
| nuclear fuel | fissionable isotope present in sufficient quantities to provide a self-sustaining chain reaction in a nuclear reactor | ||||
| nuclear moderator | substance that slows neutrons to a speed low enough to cause fission | ||||
| nuclear reaction | change to a nucleus resulting in changes in the atomic number, mass number, or energy state | ||||
| nuclear reactor | environment that produces energy via nuclear fission in which the chain reaction is controlled and sustained without explosion | ||||
| nuclear transmutation | conversion of one nuclide into another nuclide | ||||
| nucleon | collective term for protons and neutrons in a nucleus | ||||
| nuclide | nucleus of a particular isotope | ||||
| parent nuclide | unstable nuclide that changes spontaneously into another (daughter) nuclide | ||||
| particle accelerator | device that uses electric and magnetic fields to increase the kinetic energy of nuclei used in transmutation reactions | ||||
| positron or | antiparticle to the electron; it has identical properties to an electron, except for having the opposite (positive) charge | ||||
| positron emission | (also, β+ decay) conversion of a proton into a neutron, which remains in the nucleus, and a positron, which is emitted | ||||
| radiation absorbed dose (rad) | SI unit for measuring radiation dose, frequently used in medical applications; 1 rad = 0.01 Gy | ||||
| radiation dosimeter | device that measures ionizing radiation and is used to determine personal radiation exposure | ||||
| radiation therapy | use of high-energy radiation to damage the DNA of cancer cells, which kills them or keeps them from dividing | ||||
| radioactive decay | spontaneous decay of an unstable nuclide into another nuclide | ||||
| radioactive decay series | chains of successive disintegrations (radioactive decays) that ultimately lead to a stable end-product | ||||
| radioactive tracer | (also, radioactive label) radioisotope used to track or follow a substance by monitoring its radioactive emissions | ||||
| radioactivity | phenomenon exhibited by an unstable nucleon that spontaneously undergoes change into a nucleon that is more stable; an unstable nucleon is said to be radioactive | ||||
| radiocarbon dating | highly accurate means of dating objects 30,000–50,000 years old that were derived from once-living matter; achieved by calculating the ratio of in the object vs. the ratio of in the present-day atmosphere | ||||
| radioisotope | isotope that is unstable and undergoes conversion into a different, more stable isotope | ||||
| radiometric dating | use of radioisotopes and their properties to date the formation of objects such as archeological artifacts, formerly living organisms, or geological formations | ||||
| reactor coolant | assembly used to carry the heat produced by fission in a reactor to an external boiler and turbine where it is transformed into electricity | ||||
| relative biological effectiveness (RBE) | measure of the relative damage done by radiation | ||||
| roentgen equivalent man (rem) | unit for radiation damage, frequently used in medicine; 100 rem = 1 Sv | ||||
| scintillation counter | instrument that uses a scintillator—a material that emits light when excited by ionizing radiation—to detect and measure radiation | ||||
| sievert (Sv) | SI unit measuring tissue damage caused by radiation; takes into account energy and biological effects of radiation | ||||
| strong nuclear force | force of attraction between nucleons that holds a nucleus together | ||||
| subcritical mass | amount of fissionable material that cannot sustain a chain reaction; less than a critical mass | ||||
| supercritical mass | amount of material in which there is an increasing rate of fission | ||||
| transmutation reaction | bombardment of one type of nuclei with other nuclei or neutrons | ||||
| transuranium element | element with an atomic number greater than 92; these elements do not occur in nature |