Iodine-138
Properties and data of the isotope 138I.
See also: List of individual Iodine isotopes (and general data sources).
General data
Name of the isotope:Iodine-138; I-138Other names:Jod-138Symbol:138I or 13853IMass number A:138 (= number of nucleons)Atomic number Z:53 (= number of protons)Neutrons N:85Nucleon pairing (Z - N):odd - oddNuclear ratio (N/Z ratio):1.6037735849057 (= neutron-proton ratio)Neutron excess (N-Z):32Isotopic mass:137.922726(6) u (atomic weight of Iodine-138)Nuclide mass:137.8936531 u (calculated nuclear mass without electrons)Mass excess:-71.98027 MeVMass defect:1.228518556 u (per nucleus)Nuclear binding energy:1144.3576638 MeV (per nucleus)
8.29244684 MeV (average binding energy per nucleon)Separation energy:SN = 3.695(10) MeV (first neutron)
SP = 9.965(6) MeV (first proton)Half-life:6.26(3) sDecay constant λ:0.11072638667092 s-1Specific activity α:4.86722552878 × 10+20 Bq g-1
13154663591.322 Ci g-1Spin and parity:
(nuclear angular momentum)(1-)Year of discovery:1949
Radioactive Decay
Half-life T½ = 6.26(3) s.
Decay
mode | Daughter | Probability | Decay energy | γ energy
(intensity) |
|---|
| β- | 138Xe | 94.54 % | 7.992(7) MeV | |
| β-, n | 137Xe | 5.46 % | 2.332(6) MeV | |
Parent Nuclides
Direct parent isotope is: 138Te.
Nuclear Isomers
Nuclear isomers or excited states with the activation energy in keV related to the ground state.
| Nuclear Isomer | Excitation Energy | Half-life | Spin |
|---|
| 138mI | 67.9(3) keV | 1.26(16) μs | (3-) |
Isotones and Isobars
The following table shows the atomic nuclei that are isotonic (same neutron number N = 85) and isobaric (same nucleon number A = 138) with Iodine-138. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.
| Z | Isotone N = 85 | Isobar A = 138 |
|---|
| 47 | 132Ag | |
| 48 | 133Cd | |
| 49 | 134In | |
| 50 | 135Sn | 138Sn |
| 51 | 136Sb | 138Sb |
| 52 | 137Te | 138Te |
| 53 | 138I | 138I |
| 54 | 139Xe | 138Xe |
| 55 | 140Cs | 138Cs |
| 56 | 141Ba | 138Ba |
| 57 | 142La | 138La |
| 58 | 143Ce | 138Ce |
| 59 | 144Pr | 138Pr |
| 60 | 145Nd | 138Nd |
| 61 | 146Pm | 138Pm |
| 62 | 147Sm | 138Sm |
| 63 | 148Eu | 138Eu |
| 64 | 149Gd | 138Gd |
| 65 | 150Tb | 138Tb |
| 66 | 151Dy | 138Dy |
| 67 | 152Ho | |
| 68 | 153Er | |
| 69 | 154Tm | |
| 70 | 155Yb | |
| 71 | 156Lu | |
| 72 | 157Hf | |
| 73 | 158Ta | |
| 74 | 159W | |
| 75 | 160Re | |
| 76 | 161Os | |
External data and identifiers
Literature and References
[1] - R. C. Greenwood, K. D. Watts:
Delayed Neutron Energy Spectra of 87Br, 88Br, 89Br, 90Br, 137I, 138I, 139I, and 136Te.
In: Nuclear Science and Engineering, Volume 126, (2017), DOI 10.13182/NSE97-A24484.
Last update: 2023-04-27
Perma link: https://www.chemlin.org/isotope/iodine-138
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