Isotopes of iodine

There are 37 known isotopes of iodine (I) from ¹⁰⁸I to ¹⁴⁴I; all undergo radioactive decay but only one, ¹²⁷I, is stable. Iodine is thus a monoisotopic element.

Its longest-lived radioactive isotope, ¹²⁹I, has a half-life of 15.7 million years, which is far too short for it to exist as a primordial nuclide. Cosmogenic sources of ¹²⁹I produce very tiny quantities of it that are too small to affect atomic weight measurements; iodine is thus also a mononuclidic element—one that is found in nature only as a single nuclide. Most ¹²⁹I derived radioactivity on Earth is man-made: an unwanted long-lived byproduct of early nuclear tests and nuclear fission accidents.

All other iodine radioisotopes have half-lives less than 60 days, and four of these are used as tracers and therapeutic agents in medicine. These are ¹²³I, ¹²⁴I, ¹²⁵I, and ¹³¹I. All industrial production of radioactive iodine isotopes involves these four useful radionuclides.

The isotope ¹³⁵I has a half-life less than seven hours, which is too short to be used in biology. Unavoidable in situ production of this isotope is important in nuclear reactor control, as it decays to ¹³⁵Xe, the most powerful known neutron absorber, and the nuclide responsible for the so-called iodine pit phenomenon.

Radioiodine (disambiguation)

Radioiodine or Radioisotopes of iodine or Isotopes of iodine may refer to:

Radioactive decay products of the chemical element iodine such as