Xenon-129m
Properties and data of the isotope 129mXe.
See also: List of individual Xenon isotopes (and general data sources).
General data
Name of the isotope:Xenon-129m; Xe-129mSymbol:129mXe or 129m54XeMass number A:129 (= number of nucleons)Atomic number Z:54 (= number of protons)Neutrons N:75Nucleon pairing (Z - N):even - oddNuclear ratio (N/Z ratio):1.3888888888889 (= neutron-proton ratio)Neutron excess (N-Z):21Excitation energy:236.14(3) keVIsotopic mass:128.90478086(4) u (atomic weight of Xenon-129m)Nuclide mass:128.8751595 u (calculated nuclear mass without electrons)Mass excess:-88.69606 MeVMass defect:1.167639568 u (per nucleus)Nuclear binding energy:1087.64925175 MeV (per nucleus)
8.43138955 MeV (average binding energy per nucleon)Half-life:8.88(2) dDecay constant λ:9.034388301842 × 10-7 s-1Specific activity α:4.25049679195 × 10+15 Bq g-1
114878.29167454 Ci g-1Spin and parity:
(nuclear angular momentum)11/2-Magnetic dipole moment:μ(μN) = -0.891170(10)Quadrupole moment Q:+0.63(2) barn (100 fm2)Nuclear g-factor:gl = -0.16203090909091
Radioactive Decay
Half-life T½ = 8.88(2) d respectively 7.67232 × 105 seconds s.
Decay
mode | Daughter | Probability | Decay energy | γ energy
(intensity) |
|---|
| Iso | 129Xe | 100 % | | |
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 |
|---|
| 129Xe | | stable | 1/2+ |
Isotones and Isobars
The following table shows the atomic nuclei that are isotonic (same neutron number N = 75) and isobaric (same nucleon number A = 129) with Xenon-129m. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.
| Z | Isotone N = 75 | Isobar A = 129 |
|---|
| 42 | 117Mo | |
| 43 | 118Tc | |
| 44 | 119Ru | |
| 45 | 120Rh | |
| 46 | 121Pd | 129Pd |
| 47 | 122Ag | 129Ag |
| 48 | 123Cd | 129Cd |
| 49 | 124In | 129In |
| 50 | 125Sn | 129Sn |
| 51 | 126Sb | 129Sb |
| 52 | 127Te | 129Te |
| 53 | 128I | 129I |
| 54 | 129Xe | 129Xe |
| 55 | 130Cs | 129Cs |
| 56 | 131Ba | 129Ba |
| 57 | 132La | 129La |
| 58 | 133Ce | 129Ce |
| 59 | 134Pr | 129Pr |
| 60 | 135Nd | 129Nd |
| 61 | 136Pm | 129Pm |
| 62 | 137Sm | 129Sm |
| 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/xenon-129m
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