Iodine: isotope data

Naturally occurring isotopes

This table shows information about naturally occuring isotopes, their atomic masses, their natural abundances, their nuclear spins, and their magnetic moments. Further data for radioisotopes (radioactive isotopes) of iodine are listed (including any which occur naturally) below.
Isotope Mass / Da Natural abundance (atom %) Nuclear spin (I) Magnetic moment (μ/μN)
127I 126.904473 (5) 100 5/2 2.81328

In the above, the most intense ion is set to 100% since this corresponds best to the output from a mass spectrometer. This is not to be confused with the relative percentage isotope abundances which totals 100% for all the naturally occurring isotopes.

Radiosotope data

Further data for naturally occuring isotopes of iodine are listed above. This table gives information about some radiosotopes of iodine, their masses, their half-lives, their modes of decay, their nuclear spins, and their nuclear magnetic moments.
Isotope Mass / Da Half-life Mode of decay Nuclear spin Nuclear magnetic moment
120I 119.91005 1.35 h EC to 120Te 2 1.23
121I 120.90737 2.12 h EC to 121Te 5/2 2.3
122I 121.90760 3.6 m EC to 122Te 1 0.94
123I 122.905605 13.2 h EC to 123Te 5/2 2.82
124I 123.906211 4.18 d EC to 124Te 2 1.44
125I 124.904624 59.4 d EC to 125Te 5/2 2.82
126I 125.905619 13.0 d EC to 126Te; β- to 126Xe 2 1.44
128I 127.905805 25.0 m EC to 128Te; β- to 128Xe 1
129I 128.904988 1.7 x 107 y β- to 129Xe 7/2 2.621
130I 129.906674 12.36 h β- to 130Xe 5 3.35
131I 130.906125 8.040 d β- to 131Xe 7/2 2.742
132I 131.90800 2.28 h β- to 132Xe 4
133I 132.90781 20.8 h β- to 133Xe 7/2 2.86
134I 133.9099 52.6 m β- to 134Xe 4
135I 134.91005 6.57 h β- to 135Xe 7/2

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  1. Naturally occurring isotope abundances: Commission on Atomic Weights and Isotopic Abundances report for the International Union of Pure and Applied Chemistry in Isotopic Compositions of the Elements 1989, Pure and Applied Chemistry, 1998, 70, 217. [Copyright 1998 IUPAC]
  2. For further information about radioisotopes see Jonghwa Chang's (Korea Atomic Energy Research Institute) Table of the Nuclides
  3. Masses, nuclear spins, and magnetic moments: I. Mills, T. Cvitas, K. Homann, N. Kallay, and K. Kuchitsu in Quantities, Units and Symbols in Physical Chemistry, Blackwell Scientific Publications, Oxford, UK, 1988. [Copyright 1988 IUPAC]

NMR Properties of iodine

Common reference compound: KI/D2O.

Table of NMR-active nucleus propeties of iodine
  Isotope 1 Isotope 2 Isotope 3
Isotope 127I 129I
Natural abundance /% 100
Spin (I) 5/2
Frequency relative to 1H = 100 (MHz) 20.008630
Receptivity, DP, relative to 1H = 1.00 0.0954
Receptivity, DC, relative to 13C = 1.00 545
Magnetogyric ratio, γ (107 rad T‑1 s-1) 5.389573
Magnetic moment, μ (μN) 3.328710
Nuclear quadrupole moment, Q/millibarn -696(12), and -624(11) [Mössbauer state] -604(10) [Mössbauer state]
Line width factor, 1056 l (m4) 0.19


  1. R.K. Harris in Encyclopedia of Nuclear Magnetic Resonance, D.M. Granty and R.K. Harris, (eds.), vol. 5, John Wiley & Sons, Chichester, UK, 1996. I am grateful to Professor Robin Harris (University of Durham, UK) who provided much of the NMR data, which are copyright 1996 IUPAC, adapted from his contribution contained within this reference.
  2. J. Mason in Multinuclear NMR, Plenum Press, New York, USA, 1987. Where given, data for certain radioactive nuclei are from this reference.
  3. P. Pyykkö, Mol. Phys., 2008, 106, 1965-1974.
  4. P. Pyykkö, Mol. Phys., 2001, 99, 1617-1629.
  5. P. Pyykkö, Z. Naturforsch., 1992, 47a, 189. I am grateful to Professor Pekka Pyykkö (University of Helsinki, Finland) who provided the nuclear quadrupole moment data in this and the following two references.
  6. D.R. Lide, (ed.), CRC Handbook of Chemistry and Physics 1999-2000 : A Ready-Reference Book of Chemical and Physical Data (CRC Handbook of Chemistry and Physics, CRC Press, Boca Raton, Florida, USA, 79th edition, 1998.
  7. P. Pyykkö, personal communication, 1998, 204, 2008, 2010.

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