Promethium-155
Properties and data of the isotope 155Pm.
See also: list of Promethium isotopes.
General data
Name of the isotope:Promethium-155; Pm-155Symbol:155Pm or 15561PmMass number A:155 (= number of nucleons)Atomic number Z:61 (= number of protons)Neutrons N:94Isotopic mass:154.928137(5) u (atomic weight of Promethium-155)Nuclide mass:154.8946762 u (calculated nuclear mass without electrons)Mass excess:-66.93995 MeVMass defect:1.363692056 u (per nucleus)Nuclear binding energy:1270.27096801 MeV (per nucleus)
8.19529657 MeV (average binding energy per nucleon)Separation energy:SN = 6.50(5) MeV (first neutron)
SP = 8.40(5) MeV (first proton)Half-life:41.5(2) sDecay constant λ:0.01670234170024 s-1Specific activity α:6.53141911750 × 10+19 Bq g-1
1765248410.1376 Ci g-1Spin and parity:
(nuclear angular momentum)5/2-Year of discovery:1982
Radioactive Decay
Half-life T½ = 41.5(2) s respectively 4.15 × 101 seconds s.
Decay mode | Daughter | Probability | Decay energy | γ energy (intensity) |
---|
β- | 155Sm | 100 % | 3.251(5) MeV | |
Parent Nuclides
Direct parent isotope is: 155Nd.
Isotones and Isobars
The following table shows the atomic nuclei that are isotonic (same neutron number N = 94) and isobaric (same nucleon number A = 155) with Promethium-155. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.
Z | Isotone N = 94 | Isobar A = 155 |
54 | 148Xe | |
55 | 149Cs | |
56 | 150Ba | |
57 | 151La | 155La |
58 | 152Ce | 155Ce |
59 | 153Pr | 155Pr |
60 | 154Nd | 155Nd |
61 | 155Pm | 155Pm |
62 | 156Sm | 155Sm |
63 | 157Eu | 155Eu |
64 | 158Gd | 155Gd |
65 | 159Tb | 155Tb |
66 | 160Dy | 155Dy |
67 | 161Ho | 155Ho |
68 | 162Er | 155Er |
69 | 163Tm | 155Tm |
70 | 164Yb | 155Yb |
71 | 165Lu | 155Lu |
72 | 166Hf | 155Hf |
73 | 167Ta | 155Ta |
74 | 168W | |
75 | 169Re | |
76 | 170Os | |
77 | 171Ir | |
78 | 172Pt | |
79 | 173Au | |
80 | 174Hg | |
External data and identifiers
Last update: 2020-10-20
Perma link: https://www.chemlin.org/isotope/promethium-155
© 1996 - 2025 ChemLin