Promethium-138m
Properties and data of the isotope 138mPm.
See also: list of Promethium isotopes.
General data
Name of the isotope:Promethium-138m; Pm-138mSymbol:138mPm or 138m61PmMass number A:138 (= number of nucleons)Atomic number Z:61 (= number of protons)Neutrons N:77Isotopic mass:137.91955(3) u (atomic weight of Promethium-138m)
Excitation energy: +x keVNuclide mass:137.8860892 u (calculated nuclear mass without electrons)Mass excess:-74.93869 MeVMass defect:1.224975484 u (per nucleus)Nuclear binding energy:1141.05731349 MeV (per nucleus)
8.26853126 MeV (average binding energy per nucleon)Half-life:3.24(5) minDecay constant λ:0.0035655719164606 s-1Specific activity α:1.567326739208 × 10+19 Bq g-1
423601821.40778 Ci g-1Spin and parity:
(nuclear angular momentum)(5-)
Radioactive Decay
Half-life T½ = 3.24(5) min (minutes) respectively 1.944 × 102 seconds s.
Decay mode | Daughter | Probability | Decay energy | γ energy (intensity) |
---|
EC/β+ | 138Nd | 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 |
---|
138Pm | | 10(2) s | (1+) |
Isotones and Isobars
The following table shows the atomic nuclei that are isotonic (same neutron number N = 77) and isobaric (same nucleon number A = 138) with Promethium-138m. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.
Z | Isotone N = 77 | Isobar A = 138 |
43 | 120Tc | |
44 | 121Ru | |
45 | 122Rh | |
46 | 123Pd | |
47 | 124Ag | |
48 | 125Cd | |
49 | 126In | |
50 | 127Sn | 138Sn |
51 | 128Sb | 138Sb |
52 | 129Te | 138Te |
53 | 130I | 138I |
54 | 131Xe | 138Xe |
55 | 132Cs | 138Cs |
56 | 133Ba | 138Ba |
57 | 134La | 138La |
58 | 135Ce | 138Ce |
59 | 136Pr | 138Pr |
60 | 137Nd | 138Nd |
61 | 138Pm | 138Pm |
62 | 139Sm | 138Sm |
63 | 140Eu | 138Eu |
64 | 141Gd | 138Gd |
65 | 142Tb | 138Tb |
66 | 143Dy | 138Dy |
67 | 144Ho | |
68 | 145Er | |
69 | 146Tm | |
External data and identifiers
Last update: 2020-10-20
Perma link: https://www.chemlin.org/isotope/promethium-138m
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