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A nuclide is a nuclear-centric term, describing an atomic species by its nuclear composition and nuclear energy state.

A nuclide has a specific number of protons and neutrons, and will additionally have a specific energy state of its nucleus.

Radionuclides are unstable nuclides that undergo radioactive decay.

Types of nuclides are demonstrated below:

  • isotopes - same atomic number (Z)
  • isotones - same neutron number (N)
  • isobars - same mass number (A)
  • isomers - same atomic (Z) and mass (A) numbers, different energy states

History and etymology

Truman Kohman, a 20th-century American chemist, proposed the use of the terms nuclide in 1947 (and its derivative radionuclide), as a more accurate substitute for the terms isotope and radioisotope. This recommendation was not widely adopted in scientific literature until the 1960s.

Imaging technology

Article information

rID: 79814
Synonyms or Alternate Spellings:
  • Radionuclide

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