isotope

Examples of isotope in the following topics:

• Radioactive Decay Series: Introduction

  • A parent isotope is one that undergoes decay to form a daughter isotope.
  • The daughter isotope may be stable, or it may itself decay to form a daughter isotope of its own.
  • The daughter of a daughter isotope is sometimes called a granddaughter isotope.
  • The time it takes for a single parent atom to decay to an atom of its daughter isotope can vary widely, not only for different parent-daughter chains, but also for identical pairings of parent and daughter isotopes.
  • When equilibrium is achieved, a granddaughter isotope is present in proportion to its half-life.

• Tracers

  • In a tracer, this substituting atom is a radioactive isotope.
  • Therefore, the radioactive isotope can be present in low concentration and its presence still detected by sensitive radiation detectors such as Geiger counters and scintillation counters.
  • Analysis of what happens to the radioactive isotope provides detailed information about the mechanism of the chemical reaction.
  • The radio-isotope provides a way to build an image showing how that compound and its reaction products are distributed around the organism.

• Half-Life and Rate of Decay; Carbon-14 Dating

  • Carbon has two stable, nonradioactive isotopes: carbon-12 (12C) and carbon-13 (13C).
  • The carbon-14 isotope would vanish from Earth's atmosphere in less than a million years were it not for the constant influx of cosmic rays interacting with molecules of nitrogen (N2) and single nitrogen atoms (N) in the stratosphere.
  • When plants fix atmospheric carbon dioxide (CO2) into organic compounds during photosynthesis, the resulting fraction of the isotope 14C in the plant tissue will match the fraction of the isotope in the atmosphere.
  • After plants die or are consumed by other organisms, the incorporation of all carbon isotopes, including 14C, stops.

• The Periodic Table

  • Most elements have differing numbers of neutrons among different atoms: these variants are referred to as isotopes.
  • For example, carbon has three naturally occurring isotopes.
  • Isotopes are never separated in the periodic table.
  • Elements with no stable isotopes have the atomic masses of their most stable isotopes listed in parentheses.

• Natural Radioactivity

  • Radon and its isotopes, parent radionuclides, and decay products all contribute to an average inhaled dose of 1.26 mSv/a.
  • However, the effects on humans of the actual diminishment (due to decay) of these isotopes is minimal.
  • Put another way, human history is so short in comparison to a half-life of a billion years that the activity of these long-lived isotopes has been effectively constant throughout our time on this planet.
  • Many shorter-half-life and therefore more intensely radioactive isotopes have not decayed out of the terrestrial environment because they are still being produced.

• Mass Spectrometer

  • This one is for the measurement of carbon dioxide isotope ratios as in the carbon-13urea breath test.

• Absolute Temperature

  • By international agreement, the unit kelvin and its scale are defined by two points: absolute zero and the triple point of Vienna Standard Mean Ocean Water (water with a specified blend of hydrogen and oxygen isotopes).

• Examples and Applications

  • In the case of isotopic carbon dioxide, each molecule has the same charge, but different masses.
  • This one is for the measurement of carbon dioxide isotope ratios (IRMS) as in the carbon-13 urea breath test.

• Atomic Theory of Matter

  • Atoms can be broken down into smaller pieces, and atoms of a given element can vary in mass and other properties (see isotopes and ions).

• Radiation from Food

  • X-ray irradiators are considered an alternative to isotope-based irradiation systems.