isotope

Examples of isotope in the following topics:

• Stable Isotopes

  • The term isotope refers to the number of neutrons a certain element contains.
  • A stable isotope is a chemical isotope that is not radioactive.
  • The element with the most stable isotopes is tin which as 10 stable isotopes.
  • Knowledge about stable isotopes is important in a variety of fields.
  • This is a table that represents atom decay yielding various isotopes.

• Structural Determination

  • NMR analysis is isotope-dependent, and it often relies on trace isotopes of a molecule for detection.
  • Adding an isotope will also change the observed mass of any fragment which contains the isotope.
  • Isotopic labeling is used to track the passage of an isotope through a reaction, metabolic pathway, or cell.
  • In isotopic labeling, there are multiple ways to detect the presence of labeling isotopes: mass, vibrational mode, or radioactive decay.
  • Identify the uses of isotopic labeling in structural determination and the primary techniques used to study isotopically-labeled molecules

• Average Atomic Mass

  • All elements exist as a collection of isotopes.
  • The average atomic mass of an element is the sum of the masses of its isotopes, each multiplied by its natural abundance (the decimal associated with percent of atoms of that element that are of a given isotope).
  • Average atomic mass = f1M1 + f2M2 + ... + fnMn where f is the fraction representing the natural abundance of the isotope and M is the mass number (weight) of the isotope.
  • For helium, there is approximately one isotope of Helium-3 for every million isotopes of Helium-4; therefore, the average atomic mass is very close to 4 amu (4.002602 amu).
  • (Lithium also has another, rarer isotope with only 2 neutrons. )

• Isotopes of Hydrogen

  • Each isotope has different chemical properties.
  • 2H, or deuterium (D), is the other stable isotope of hydrogen.
  • It is a highly unstable isotope of hydrogen.
  • 5H is another highly unstable heavy isotope of hydrogen.
  • Unique among all stable isotopes, it has no neutrons.

• Study of Photosynthesis

  • Mass spectrometry has been used to study the ratio of carbon isotopes in various plants to understand the mechanisms of photosynthesis.
  • Mass spectrometry has been used to study the ratio of isotopes in various plants to understand the mechanisms of photosynthesis.
  • Stable carbon isotopes in carbon dioxide are utilized differentially by plants during photosynthesis.
  • Grasses in temperate environments, such as barley, rice, and wheat, follow a C3 photosynthetic pathway that yields distinctive isotopic ratios.
  • Describe the use of radioactive isotopes in the study of photosynthesis

• 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.

• Isotopes

  • Since a mass spectrometer separates and detects ions of slightly different masses, it easily distinguishes different isotopes of a given element.
  • The five peaks in this spectrum demonstrate clearly that natural bromine consists of a nearly 50:50 mixture of isotopes having atomic masses of 79 and 81 amu respectively.
  • The center and right hand spectra show that chlorine is also composed of two isotopes, the more abundant having a mass of 35 amu, and the minor isotope a mass 37 amu.
  • The precise isotopic composition of chlorine and bromine is:
  • Loss of a chlorine atom gives two isotopic fragment ions at m/z=49 & 51amu, clearly incorporating a single chlorine atom.

• Isotopes

  • Isotopes do differ in their stability.
  • Unstable isotopes most commonly emit alpha particles (He2+) and electrons.
  • These atoms are called radioactive isotopes or radioisotopes.
  • Other elements have isotopes with different half lives.
  • Discuss the properties of isotopes and their use in radiometric dating

• Isotopes in Medicine

  • Common isotopes that are used in nuclear imaging include: fluorine-18, gallium-67, krypton-81m, rubidium-82, nitrogen-13, technetium-99m, indium-111, iodine-123, xenon-133, and thallium-201.
  • For this type of therapy, yttrium-90 and iodine-131 are the most commonly used isotopes.
  • These images are scans used in the evaluation of thyroid cancer using the isotope iodine-123.

• Transuranium Elements

  • However, there are exceptions, including dubnium and several isotopes of curium.
  • Blue - Elements that contain at least one stable isotope.
  • Yellow - Radioactive elements: the most stable isotope has a half-life between 800 and 34.000 years.
  • Orange - Radioactive elements: the most stable isotope has a half-life between one day and 103 years.
  • Purple - Extremely radioactive elements: the most stable isotope has a half-life less than several minutes.