Isobar (nuclear physics)

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Isobaric (from ancient Greek ἴσος isos , German , equal to ' and βαρύς Barys , German , hard' ) are nuclides of two different chemical elements , ie of different atomic number , the atomic nuclei but the same number of nucleons contained, so the same mass number have. So they differ in the number of their protons and neutrons .

The series of isobars as represented in nuclide maps as a diagonal is sometimes referred to as an isobar . It is considered, for example, in the context of the successive beta decays of fission products . The adjective isobaric in the sense of “as heavy as ...” is also used occasionally.

If the atomic number of two isobars differs by only 1, then experience has shown that at least one of these nuclides is radioactive ( Mattauch's isobar rule ).


  • 14 C and 14 N
  • 17 N , 17 O and 17 F

The so-called mirror cores are a special case of isobars .


  • Povh, Rith, Scholz, Zetsche: Particles and Cores , Springer, 4th edition 1997, ISBN 3-540-61737-X

See also

Individual evidence

  1. a b c d Jürgen Falbe, Manfred Regitz (Ed.): RÖMPP. Dictionary. Chemistry H – L. 10th edition, Georg Thieme Verlag, Stuttgart, 1997, ISBN 3-13-734810-2 , p. 1995.
  2. z. B. Roland Lindner: Nuclear and Radiochemistry, Springer 1961, pages 14, 46, 65
  3. J. Mattauch: To the systematics of the isotopes. In: Journal of Physics . Volume 91, No. 5-6, 1934, pp. 361-371 ( doi: 10.1007 / BF01342557 ).