isotope

[ahy-suh-tohp]

noun

Chemistry.

1. any of two or more forms of a chemical element, having the same number of protons in the nucleus, or the same atomic number, but having different numbers of neutrons in the nucleus, or different atomic weights. There are 275 isotopes of the 81 stable elements, in addition to over 800 radioactive isotopes, and every element has known isotopic forms. Isotopes of a single element possess almost identical properties.

isotope

/ ˌaɪsəˈtɒpɪk, ˈaɪsəˌtəʊp, aɪˈsɒtəpɪ /

noun

1. one of two or more atoms with the same atomic number that contain different numbers of neutrons

isotope

1. One of two or more atoms that have the same atomic number (the same number of protons) but a different number of neutrons. Carbon 12, the most common form of carbon, has six protons and six neutrons, whereas carbon 14 has six protons and eight neutrons. Isotopes of a given element typically behave alike chemically. With the exception of hydrogen, elements found on Earth generally have the same number of protons and neutrons; heavier and lighter isotopes (with more or fewer neutrons) are often unstable and undergo radioactive decay.

isotope

1. In physics, different forms of the same element, with nuclei that have the same number of protons but different numbers of neutrons. Isotopes are distinguished from each other by giving the combined number of protons and neutrons in the nucleus. For example, uranium 235 is the isotope of uranium that has 235 protons and neutrons in its nucleus rather than the more commonly occurring 238. All elements have isotopes.

Other Word Forms

• isotopic adjective
• isotopically adverb
• isotopy noun

Word History and Origins

Origin of isotope¹

First recorded in 1910–15; iso- + -tope, from Greek tópos “place”; Utopia ( def. )

Word History and Origins

Origin of isotope¹

C20: from _iso- + Greek topos place

Example Sentences

To confirm the meaning of these chemical signatures, seawater samples collected by the research vessel Eugen Seibold were used to calibrate the nitrogen isotopes in modern corals, demonstrating that they reliably record nitrogen fixation.

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Here too, isotope analysis of his teeth solved the mystery, determining conclusively that his roots were not in England but in Italy.

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The group included anthropologists, geneticists, an archaeologist, an archaeobotanist, stable isotope specialists, radiocarbon experts, and dentists.

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By following how quickly these isotopes left the body through urine, the scientists were able to determine how much carbon dioxide the athletes exhaled and, in turn, estimate total calorie expenditure.

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The study, titled "Extreme triple oxygen isotope fractionation in Equisetum," examines horsetails, which are hollow-stemmed plants that have existed on the planet for more than 400 million years.

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