Encyclopedia of Astrobiology

Living Edition
| Editors: Muriel Gargaud, William M. Irvine, Ricardo Amils, Henderson James Cleaves, Daniele Pinti, José Cernicharo Quintanilla, Michel Viso


  • Francis Albarede
Living reference work entry
DOI: https://doi.org/10.1007/978-3-642-27833-4_824-3


Two nuclides, e.g., 16O and 18O, are isotopes of the same element (here oxygen), if their nucleus has the same number of protons (same charge) but a different number of neutrons (different mass numbers). Because their electronic shells must balance the nuclear charge, isotopes have the same electronic configuration and, hence, very similar chemical properties. Isotopes can be either stable or radioactive. Stable isotopes are those isotopes that do not spontaneously undergo radioactive decay. Radioactive isotopes are those with an unstable nucleus that stabilizes itself by emitting ionizing radiation (decay). Radiogenic isotopes are produced by the decay of radioactive isotopes. With few exceptions, even-number isotopes are more abundant than odd-number isotopes. The uncertainty principle requires the existence of a mass-dependent vibrational zero-point energy, which accounts for subtle differences in the chemical properties of the isotopes of the same element. This is the...


Radioactive Isotope Stable Isotope Carbon Isotope Oxygen Isotope Isotopic Fractionation 
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Copyright information

© Springer-Verlag Berlin Heidelberg 2014

Authors and Affiliations

  1. 1.Ecole Normale Supérieure de LyonLyon Cedex 7France