radioactive isotope


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radioactive isotope

or

radioisotope,

natural or artificially created isotopeisotope
, in chemistry and physics, one of two or more atoms having the same atomic number but differing in atomic weight and mass number. The concept of isotope was introduced by F.
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 of a chemical element having an unstable nucleus that decays, emitting alpha, beta, or gamma rays until stability is reached. The stable end product is a nonradioactive isotope of another element, i.e., radium-226 decays finally to lead-206. Very careful measurements show that many materials contain traces of radioactive isotopes. For a time it was thought that these materials were all members of the actinide seriesactinide series,
a series of radioactive metallic elements in Group 3 of the periodic table. Members of the series are often called actinides, although actinium (at. no. 89) is not always considered a member of the series.
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; however, exacting radiochemical research has demonstrated that certain of the light elements also have naturally occurring isotopes that are radioactive. Since minute traces of radioactive isotopes can be sensitively detected by means of the Geiger counter and other methods, they have various uses in medical therapy, diagnosis, and research. In therapy, they are used to kill or inhibit specific malfunctioning cells. Radioactive phosphorus is used to treat abnormal cell proliferation, e.g., polycythemia (increase in red cells) and leukemia (increase in white cells). Radioactive iodine can be used in the diagnosis of thyroid function and in the treatment of hyperthyroidism. Since the iodine taken into the body concentrates in the thyroid gland, the radioaction can be confined to that organ. In research, radioactive isotopes as tracertracer,
an identifiable substance used to follow the course of a physical, chemical, or biological process. In chemistry the ideal tracer has the same chemical properties as the molecule it replaces and undergoes the same reactions but can at all times be detectible and
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 agents make it possible to follow the action and reaction of organic and inorganic substances within the body, many of which could not be studied by any other means. They also help to ascertain the effects of radiation on the human organism (see radiation sicknessradiation sickness,
harmful effect produced on body tissues by exposure to radioactive substances. The biological action of radiation is not fully understood, but it is believed that a disturbance in cellular activity results from the chemical changes caused by ionization (see
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). In industry, radioactive isotopes are used for a number of purposes, including measuring the thickness of metal or plastic sheets by the amount of radiation they can stop, testing for corrosion or wear, and monitoring various processes.

radioactive isotope

[¦rād·ē·ō′ak·tiv ′ī·sə‚tōp]
(nuclear physics)
References in periodicals archive ?
President Nicola Strickland said: "Radioactive isotopes play a crucial role in diagnosing and treating cancer in the UK.
The radioactive isotope is aimed at the cancer cells by chemically attaching it to an antibody crafted to recognize the tumor by its specific antigens, or chemical signals.
Method: A prospective analysis of 91 patients undergoing sentinel lymph node biopsy who received radioactive isotope technetium-99m for the period 5 January 2010-20 June 2010.
Although we cannot predict exactly when any specific atom of [sup.87]Rb will undergo spontaneous radioactive decay, we know that extremely large quantities of any radioactive isotope will disintegrate in accord with a radioactive decay law that is expressed by the equations:
Yes, the radioactive isotope that killed Alexander Litvinenko, but don't worry it is responsible for only 4 in 1000 deaths of smokers.
The radioactive isotope is one million times more toxic than the poison used to execute prisoners in gas chambers.
Mr Litvinenko, 43, a Kremlin critic, died in late November after ingesting the radioactive isotope polonium-210.
Litvinenko died after ingesting rare radioactive isotope polonium-210.
I was reminded of this by the curious case of Alexander Litvinenko, the former Russian spy who recently died in London after being poisoned by a highly toxic radioactive isotope. While most people seem to be focused on how Mr.
Two basic types of radiation sources are available: X-ray tube or radioactive isotope. The X-ray tube is inert in the unpowered state, and it only becomes a source of radiation when activated by the operator.
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* determine the amount of a radioactive isotope remaining after specified intervals.

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