Iodine-128
Properties and data of the isotope 128I.
See also: list of Iodine isotopes.
General data
Name of the isotope:Iodine-128; I-128Other names:Jod-128Symbol:128I or 12853IMass number A:128 (= number of nucleons)Atomic number Z:53 (= number of protons)Neutrons N:75Isotopic mass:127.905809(4) u (atomic weight of Iodine-128)Nuclide mass:127.8767361 u (calculated nuclear mass without electrons)Mass excess:-87.73835 MeVMass defect:1.158786396 u (per nucleus)Nuclear binding energy:1079.40257516 MeV (per nucleus)
8.43283262 MeV (average binding energy per nucleon)Separation energy:SN = 6.82613(5) MeV (first neutron)
SP = 6.746(4) MeV (first proton)Half-life:24.99(2) minDecay constant λ:0.00046228303358673 s-1Specific activity α:2.192073657809 × 10+18 Bq g-1
59245233.994854 Ci g-1Spin and parity:
(nuclear angular momentum)1+Year of discovery:1934
Radioactive Decay
Half-life T½ = 24.99(2) min (minutes) respectively 1.4994 × 103 seconds s.
| Decay mode | Daughter | Probability | Decay energy | γ energy
(intensity) |
|---|
| β- | 128Xe | 93.1(8) % | 2.122(4) MeV | |
| EE/β+ | 128Te | 6.9(8) % | 1.255(4) MeV | |
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 |
|---|
| 128m1I | 137.851(3) keV | 0.845(20) μs | 4- |
| 128m2I | 167.368(4) keV | 175(15) ns | (6)- |
Isotones and Isobars
The following table shows the atomic nuclei that are isotonic (same neutron number N = 75) and isobaric (same nucleon number A = 128) with Iodine-128. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.
| OZ | Isotone N = 75 | Isobar A = 128 |
|---|
| 42 | 117Mo | |
| 43 | 118Tc | |
| 44 | 119Ru | |
| 45 | 120Rh | |
| 46 | 121Pd | 128Pd |
| 47 | 122Ag | 128Ag |
| 48 | 123Cd | 128Cd |
| 49 | 124In | 128In |
| 50 | 125Sn | 128Sn |
| 51 | 126Sb | 128Sb |
| 52 | 127Te | 128Te |
| 53 | 128I | 128I |
| 54 | 129Xe | 128Xe |
| 55 | 130Cs | 128Cs |
| 56 | 131Ba | 128Ba |
| 57 | 132La | 128La |
| 58 | 133Ce | 128Ce |
| 59 | 134Pr | 128Pr |
| 60 | 135Nd | 128Nd |
| 61 | 136Pm | 128Pm |
| 62 | 137Sm | 128Sm |
| 63 | 138Eu | |
| 64 | 139Gd | |
| 65 | 140Tb | |
| 66 | 141Dy | |
| 67 | 142Ho | |
| 68 | 143Er | |
| 69 | 144Tm | |
External data and identifiers
Last update: 2020-10-18
Perma link: https://www.chemlin.org/isotope/iodine-128
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