Promethium-138
Properties and data of the isotope 138Pm.
See also: list of Promethium isotopes.
General data
Name of the isotope:Promethium-138; Pm-138Symbol:138Pm or 13861PmMass 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-138)Nuclide 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)Separation energy:SN = 8.94(3) MeV (first neutron)
SP = 2.64(3) MeV (first proton)Half-life:10(2) sDecay constant λ:0.069314718055995 s-1Specific activity α:3.046883181021 × 10+20 Bq g-1
8234819408.1673 Ci g-1Spin and parity:
(nuclear angular momentum)(1+)Year of discovery:1981
Radioactive Decay
Half-life T½ = 10(2) s respectively 1.0 × 101 seconds s.
Decay mode | Daughter | Probability | Decay energy | γ energy (intensity) |
---|
EC/β+ | 138Nd | 100 % | 7.08(3) MeV | |
Parent Nuclides
Direct parent isotope is: 138Sm.
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 |
---|
138mPm | +x keV | 3.24(5) min | (5-) |
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-138. 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-138
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