radioactive isotope | Description, Uses, & Examples | ko-en.info
Radioactive isotope, also called radioisotope, radionuclide, or radioactive nuclide, any of several species of the same chemical element with different masses. Isotopes are variants of a particular chemical element which differ in neutron number, and . In most cases, for obvious reasons, if an element has stable isotopes, those . They are a minority in comparison to the even-even isotopes, which are .. A technique similar to radioisotopic labeling is radiometric dating: using the. By this definition, there are known stable isotopes of the 80 elements which They play an important role in radiometric dating and isotope geochemistry.
More than 1, radioactive isotopes of the various elements are known. Approximately 50 of these are found in nature; the rest are produced artificially as the direct products of nuclear reactions or indirectly as the radioactive descendants of these products.
- Keep Exploring Britannica
- Navigation menu
- Key Concepts
Radioactive isotopes have many useful applications. In medicinefor example, cobalt is extensively employed as a radiation source to arrest the development of cancer.
Other radioactive isotopes are used as tracers for diagnostic purposes as well as in research on metabolic processes. When a radioactive isotope is added in small amounts to comparatively large quantities of the stable element, it behaves exactly the same as the ordinary isotope chemically; it can, however, be traced with a Geiger counter or other detection device.
Iodine has proved effective in treating hyperthyroidism. Another medically important radioactive isotope is carbonwhich is used in a breath test to detect the ulcer -causing bacteria Heliobacter pylori.
What are radioisotopes?
In industryradioactive isotopes of various kinds are used for measuring the thickness of metal or plastic sheets; their precise thickness is indicated by the strength of the radiations that penetrate the material being inspected.
They also may be employed in place of large X-ray machines to examine manufactured metal parts for structural defects. Adding in the radioactive nuclides that have been created artificially, there are 3, currently known nuclides.
See list of nuclides for details. Radioactive isotopes[ edit ] The existence of isotopes was first suggested in by the radiochemist Frederick Soddybased on studies of radioactive decay chains that indicated about 40 different species referred to as radioelements i.
Soddy proposed that several types of atoms differing in radioactive properties could occupy the same place in the table. Thomson 's photographic plate are the separate impact marks for the two isotopes of neon: Richards found variations between the atomic weight of lead from different mineral sources, attributable to variations in isotopic composition due to different radioactive origins.
Thomson in as part of his exploration into the composition of canal rays positive ions. Each stream created a glowing patch on the plate at the point it struck.
Thomson observed two separate patches of light on the photographic plate see imagewhich suggested two different parabolas of deflection. Thomson eventually concluded that some of the atoms in the neon gas were of higher mass than the rest. Aston subsequently discovered multiple stable isotopes for numerous elements using a mass spectrograph.Half-life and carbon dating
In Aston studied neon with sufficient resolution to show that the two isotopic masses are very close to the integers 20 and 22, and that neither is equal to the known molar mass This is an example of Aston's whole number rule for isotopic masses, which states that large deviations of elemental molar masses from integers are primarily due to the fact that the element is a mixture of isotopes.
Aston similarly showed[ when?