Iodine-131
Properties and data of the isotope 131I.
See also: List of individual Iodine isotopes (and general data sources).
General data
Name of the isotope:Iodine-131; I-131Other names:Radioiod. Jod-131Symbol:131I or 13153IMass number A:131 (= number of nucleons)Atomic number Z:53 (= number of protons)Neutrons N:78Nucleon pairing (Z - N):odd - evenNuclear ratio (N/Z ratio):1.4716981132075 (= neutron-proton ratio)Neutron excess (N-Z):25Isotopic mass:130.9061264(6) u (atomic weight of Iodine-131)Nuclide mass:130.8770535 u (calculated nuclear mass without electrons)Mass excess:-87.4427 MeVMass defect:1.184463744 u (per nucleus)Nuclear binding energy:1103.32087075 MeV (per nucleus)
8.42229672 MeV (average binding energy per nucleon)Separation energy:SN = 8.578(3) MeV (first neutron)
SP = 7.3787(6) MeV (first proton)Half-life:8.0252(6) dDecay constant λ:9.9966814684 × 10-7 s-1Specific activity α:4.630878764211 × 10+15 Bq g-1
125158.88551922 Ci g-1Spin and parity:
(nuclear angular momentum)7/2+Magnetic dipole moment:μ(μN) = + 2.738(1)Quadrupole moment Q:- 0.35(2) barn (100 fm2)Nuclear g-factor:gl = 0.78228571428571Year of discovery:1938
Radioactive Decay
Half-life T½ = 8.0252(6) d respectively 6.9337728 × 105 seconds s.
Decay
mode | Daughter | Probability | Decay energy | γ energy
(intensity) |
|---|
| β- | 131Xe | 100 % | 0.9708(6) MeV | 364.489(5) MeV
81.5(8) % |
Parent Nuclides
Direct parent isotope is: 131Te.
Isotones and Isobars
The following table shows the atomic nuclei that are isotonic (same neutron number N = 78) and isobaric (same nucleon number A = 131) with Iodine-131. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.
| Z | Isotone N = 78 | Isobar A = 131 |
|---|
| 43 | 121Tc | |
| 44 | 122Ru | |
| 45 | 123Rh | |
| 46 | 124Pd | |
| 47 | 125Ag | 131Ag |
| 48 | 126Cd | 131Cd |
| 49 | 127In | 131In |
| 50 | 128Sn | 131Sn |
| 51 | 129Sb | 131Sb |
| 52 | 130Te | 131Te |
| 53 | 131I | 131I |
| 54 | 132Xe | 131Xe |
| 55 | 133Cs | 131Cs |
| 56 | 134Ba | 131Ba |
| 57 | 135La | 131La |
| 58 | 136Ce | 131Ce |
| 59 | 137Pr | 131Pr |
| 60 | 138Nd | 131Nd |
| 61 | 139Pm | 131Pm |
| 62 | 140Sm | 131Sm |
| 63 | 141Eu | 131Eu |
| 64 | 142Gd | |
| 65 | 143Tb | |
| 66 | 144Dy | |
| 67 | 145Ho | |
| 68 | 146Er | |
| 69 | 147Tm | |
| 70 | 148Yb | |
| 71 | 149Lu | |
External data and identifiers
Last update: 2023-05-22
Perma link: https://www.chemlin.org/isotope/iodine-131
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