| 单词 | isotope |
| 释义 | isotope (once / 12876 pages) n An isotope of a chemical element is an atom that has a different number of neutrons (that is, a greater or lesser atomic mass) than the standard for that element. The atomic number is the number of protons in an atom's nucleus. Atomic mass adds to that the number of neutrons in the nucleus. Each element has a typical atomic mass, but when the number of protons stays the same and the number of neutrons changes, you have an isotope. These can be stable, like Deuterium, an isotope of Hydrogen that has one extra neutron, or they can be radioactive, like Plutonium-239, which is a component of nuclear waste. WORD FAMILYisotope: isotopes, isotopic USAGE EXAMPLESIn addition to nuclear power plants, the radioactive isotopes used in medicine are under the NRC’s jurisdiction. Seattle Times(Dec 15, 2016) Earth-systems models link together slow shifts in atmospheric carbon, sea levels and isotopes in seawater and marine deposits. Nature(Dec 06, 2016) The Virginia-based National Center for Missing & Exploited Children arranged chemical isotope testing on the Jane Doe’s teeth and bones samples through the Smithsonian. Washington Times(Dec 06, 2016) n one of two or more atoms with the same atomic number but with different numbers of neutrons Hypo|Hyper radioisotope a radioactive isotope of an element; produced either naturally or artificially deuterium, heavy hydrogenan isotope of hydrogen which has one neutron (as opposed to zero neutrons in hydrogen) tracer(radiology) any radioactive isotope introduced into the body to study metabolism or other biological processes labela radioactive isotope that is used in a compound in order to trace the mechanism of a chemical reaction iodine-131heavy radioactive isotope of iodine with a half-life of 8 days; used in a sodium salt to diagnose thyroid disease and to treat goiter iodine-125light radioactive isotope of iodine with a half-life of 60 days; used as a tracer in thyroid studies and as a treatment for hyperthyroidism atom (physics and chemistry) the smallest component of an element having the chemical properties of the element |
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