|Isotope||Atomic mass (Da)||Isotopic abundance (amount fraction)|
Iodine is a monoisotopic element and its atomic weight is determined solely by its isotope 127I. The Commission last revised the standard atomic weight of iodine in 1985 based on the latest Atomic Mass Evaluation by IUPAP.
129I has been measured in terrestrial samples that have been exposed to cosmic radiation, and in materials that contain fallout from nuclear explosions. These measurements can be used for geochronological and environmental studies, but they also confirm the low abundance of 129I in nature, and its insignificance with respect to the atomic weight of iodine.
© IUPAC 2003