isotope (ī`sətōp), in chemistry and physics, one of two or more atoms having the same atomic number but differing in atomic weight atomic weight, mean (weighted average) of the masses of all the naturally occurring isotopes of a chemical element , as contrasted with atomic mass , which is the mass of any individual isotope.
..... Click the link for more information. and mass number. The concept of isotope was introduced by F. Soddy in explaining aspects of radioactivity; the first stable isotope (of neon) was discovered by J. J. Thomson. The nuclei of isotopes contain identical numbers of protons, equal to the atomic number of the atom, and thus represent the same chemical element, but do not have the same number of neutrons. Thus isotopes of a given element have identical chemical properties but slightly different physical properties and very different half-lives, if they are radioactive (see half-life half-life, measure of the average lifetime of a radioactive substance (see radioactivity ) or an unstable subatomic particle. One half-life is the time required for one half of any given quantity of the substance to decay.
..... Click the link for more information. ). For most elements, both stable and radioactive isotopes are known. Radioactive isotopes radioactive isotope or radioisotope, natural or artificially created isotope of a chemical element having an unstable nucleus that decays, emitting alpha, beta, or gamma rays until stability is reached.
..... Click the link for more information. of many common elements, such as carbon and phosphorus, are used as tracers in medical, biological, and industrial research. Their radioactive nature makes it possible to follow the substances in their paths through a plant or animal body and through many chemical and mechanical processes; thus a more exact knowledge of the processes under investigation can be obtained. The very slow and regular transmutations of certain radioactive substances, notably carbon-14, make them useful as "nuclear clocks" for dating dating, the determination of the age of an object, of a natural phenomenon, or of a series of events. There are two basic types of dating methods, relative and absolute.
..... Click the link for more information. archaeological and geological samples. By taking advantage of the slight differences in their physical properties, the isotopes may be separated. The mass spectrograph mass spectrograph, device used to separate electrically charged particles according to their masses; a form of the instrument known as a mass spectrometer is often used to measure the masses of isotopes of elements. J. J. Thomson and F. W. Aston showed (c.
..... Click the link for more information. uses the slight difference in mass to separate different isotopes of the same element. Depending on their nuclear properties, the isotopes thus separated have important applications in nuclear energy. For example, the highly fissionable isotope uranium-235 must be separated from the more plentiful isotope uranium-238 before it can be used in a nuclear reactor nuclear reactor, device for producing controlled release of nuclear energy . Reactors can be used for research or for power production. A research reactor is designed to produce various beams of radiation for experimental application; the heat produced is a waste
..... Click the link for more information. or atomic bomb atomic bomb or A-bomb, weapon deriving its explosive force from the release of atomic energy through the fission (splitting) of heavy nuclei (see nuclear energy ). The first atomic bomb was produced at the Los Alamos, N.Mex.
..... Click the link for more information. .

isotope

One of two or more species of atoms of a chemical element having nuclei with the same number of protons but different numbers of neutrons. They have the same atomic number and hence nearly identical chemical behaviour but different atomic masses. Most elements found in nature are mixtures of several isotopes; tin, for example, has 10 isotopes. In most cases, only stable isotopes of elements are found in nature. The radioactive forms break down spontaneously into different elements (see radioactivity). Isotopes of all elements heavier than bismuth are radioactive; some occur naturally because they have long half-lives.

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isotope

isotope
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