Lanthanum-131
Properties and data of the isotope 131La.
See also: List of individual Lanthanum isotopes (and general data sources).
General data
Name of the isotope:Lanthanum-131; La-131Symbol:131La or 13157LaMass number A:131 (= number of nucleons)Atomic number Z:57 (= number of protons)Neutrons N:74Isotopic mass:130.91007(3) u (atomic weight of Lanthanum-131)Nuclide mass:130.8788031 u (calculated nuclear mass without electrons)Mass excess:-83.76926 MeVMass defect:1.177160608 u (per nucleus)Nuclear binding energy:1096.51804339 MeV (per nucleus)
8.37036674 MeV (average binding energy per nucleon)Separation energy:SN = 10.21(4) MeV (first neutron)
SP = 3.797(28) MeV (first proton)Half-life:59(2) minDecay constant λ:0.00019580428829377 s-1Specific activity α:9.070469269882 × 10+17 Bq g-1
24514781.810494 Ci g-1Spin and parity:
(nuclear angular momentum)3/2+Year of discovery:1951
Radioactive Decay
Half-life T½ = 59(2) min (minutes) respectively 3.540 × 103 seconds s.
Decay
mode | Daughter | Probability | Decay energy | γ energy
(intensity) |
|---|
| EC/β+ | 131Ba | 100 % | 2.914(28) MeV | |
Parent Nuclides
Direct parent isotope is: 131Ce.
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 |
|---|
| 131mLa | 304.52(24) keV | 170(7) μs | 11/2- |
Isotones and Isobars
The following table shows the atomic nuclei that are isotonic (same neutron number N = 74) and isobaric (same nucleon number A = 131) with Lanthanum-131. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.
| Z | Isotone N = 74 | Isobar A = 131 |
|---|
| 41 | 115Nb | |
| 42 | 116Mo | |
| 43 | 117Tc | |
| 44 | 118Ru | |
| 45 | 119Rh | |
| 46 | 120Pd | |
| 47 | 121Ag | 131Ag |
| 48 | 122Cd | 131Cd |
| 49 | 123In | 131In |
| 50 | 124Sn | 131Sn |
| 51 | 125Sb | 131Sb |
| 52 | 126Te | 131Te |
| 53 | 127I | 131I |
| 54 | 128Xe | 131Xe |
| 55 | 129Cs | 131Cs |
| 56 | 130Ba | 131Ba |
| 57 | 131La | 131La |
| 58 | 132Ce | 131Ce |
| 59 | 133Pr | 131Pr |
| 60 | 134Nd | 131Nd |
| 61 | 135Pm | 131Pm |
| 62 | 136Sm | 131Sm |
| 63 | 137Eu | 131Eu |
| 64 | 138Gd | |
| 65 | 139Tb | |
| 66 | 140Dy | |
| 67 | 141Ho | |
External data and identifiers
Last update: 2020-10-19
Perma link: https://www.chemlin.org/isotope/lanthanum-131
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