Definitions

from The American Heritage® Dictionary of the English Language, 4th Edition

  • n. One of two or more atoms having the same atomic number but different mass numbers.

from Wiktionary, Creative Commons Attribution/Share-Alike License

  • n. Any of two or more forms of an element where the atoms have the same number of protons, but a different number of neutrons within their nuclei. As a consequence, atoms for the same isotope will have the same atomic number but a different mass number (atomic weight).
  • v. To define or demonstrate an isotopy of (one map with another).

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

  • n. one of two or more atoms with the same atomic number but with different numbers of neutrons

Etymologies

iso- + Greek topos, place (so called because the isotopes of a chemical element occupy the same position in the periodic table of elements).
(American Heritage® Dictionary of the English Language, Fourth Edition)
Coined in 1914 by British chemist Frederick Soddy from Ancient Greek ἴσος (ísos, "equal; same") and τόπος (tópos, "place"), because the different isotopes of a chemical element always occupy the same position in the periodic table of elements. Compare the synonymous Icelandic word samsæta. (Wiktionary)

Examples

  • In helium that occurs naturally the heavier isotope is more frequent than the lighter one by a factor of about 10 million.

    The Nobel Prize in Physics 2003 - Information for the Public

  • The U-235 isotope is the all-important factor making uranium an effective fuel for electric generating plants.

    Churchill Falls and Beyond

  • As we have said, during the irradiation of heavy elements by neutrons, the neutrons are captured and incorporated in the nucleus, and an isotope is thus formed of the primary substance, and this isotope is radioactive.

    Nobel Prize in Physics 1938 - Presentation Speech

  • This occurs in nature, although rarely; among 12,500 ordinary oxygen atoms, one oxygen isotope is found.

    Nobel Prize in Physics 1938 - Presentation Speech

  • If the government doesn't accept the recommendation to build a new reactor, the other options to secure a long-term isotope supply will have to be revisited, the report said.

    Dose.ca Music briefs

  • The primary by-product of enrichment is depleted uranium (DU), principally the U-238 isotope, which is stored either as UF6 or U3O8.

    Nuclear waste management

  • The half-life of an isotope is the amount of time it takes for half of its atoms to decay.

    Egonomics

  • The isotope, which is extremely hazardous, was en route to

    ANC Daily News Briefing

  • We look forward to working with the Government to create a solution to Canada's long term isotope needs, "comments Lloyd Scott, President of Iotron Industries.

    THE MEDICAL NEWS

  • The ratios make their way into people's hair when they drink the local water, and can be measured using a machine called an isotope ratio mass spectrometer.

    CBC | Top Stories News

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