Lanthanum-138
Properties and data of the isotope 138La.
See also: List of individual Lanthanum isotopes (and general data sources).
General data
Name of the isotope:Lanthanum-138; La-138Symbol:138La or 13857LaMass number A:138 (= number of nucleons)Atomic number Z:57 (= number of protons)Neutrons N:81Nucleon pairing (Z - N):odd - oddNuclear ratio (N/Z ratio):1.4210526315789 (= neutron-proton ratio)Neutron excess (N-Z):24Isotopic mass:137.907118(3) u (atomic weight of Lanthanum-138)Nuclide mass:137.8758511 u (calculated nuclear mass without electrons)Mass excess:-86.51903 MeVMass defect:1.24076702 u (per nucleus)Nuclear binding energy:1155.76703453 MeV (per nucleus)
8.37512344 MeV (average binding energy per nucleon)Separation energy:SN = 7.450(4) MeV (first neutron)
SP = 6.087(3) MeV (first proton)Half-life:1.02(1) × 1011 aDecay constant λ:2.133937175697 × 10-19 s-1Specific activity α:938.01972688384 Bq g-1
2.535188451037 × 10-8 Ci g-1Spin and parity:
(nuclear angular momentum)5+Magnetic dipole moment:μ(μN) = +3.7084(2)Charge radius:4.8473(51) femtometer fmYear of discovery:1947
Radioactive Decay
Half-life T½ = 1.02(1) × 1011 a respectively 3.248208 × 1018 seconds s.
Decay
mode | Daughter | Probability | Decay energy | γ energy
(intensity) |
|---|
| β+ | 138Ba | 65.6(5) % | 1.742(3) MeV | |
| β- | 138Ce | 34.4(5) % | 1.052(4) MeV | |
Occurrence
Comparison of the natural Lanthanum isotopes including isotopic abundance (mole fraction of the isotope mixture in percent):
| | Atomic Mass ma | Quantity | Half-life | Spin |
|---|
Lanthanum
Isotopic mixture | 138.90547 u | 100 % | | |
| Isotope 138La | 137.907118(3) u | 0.08881(71) % | 1.02(1) × 1011 a | 5+ |
| Isotope 139La | 138.90636(2) u | 99.91119(71) % | stable | 7/2+ |
NMR data
Nuclear magnetic properties and parameters of the NMR active Nuclide 138La
Isotope:138La-NMRQuantity:0.08881(71) %Spin:5+Nuclearmagnetic moment
μ/μN:+3.7084(2)Gyromagnetic ratio γ:3.5575 · 107 rad T-1 s-1Nuclear g-factor:gl = 0.74168Quadrupole moment Q:+ 0.45(2) barn (100 fm2)Resonance frequency:v0 = 5.6615 MHz at 1 TRelative Sensitivity:[related to 1H = 1.000]:
0.09404 (H0 = const.)
5.3189 (v0 = const.)
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 |
|---|
| 138mLa | 72.57(3) keV | 116(5) ns | (3)+ |
Isotones and Isobars
The following table shows the atomic nuclei that are isotonic (same neutron number N = 81) and isobaric (same nucleon number A = 138) with Lanthanum-138. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.
| Z | Isotone N = 81 | Isobar A = 138 |
|---|
| 45 | 126Rh | |
| 46 | 127Pd | |
| 47 | 128Ag | |
| 48 | 129Cd | |
| 49 | 130In | |
| 50 | 131Sn | 138Sn |
| 51 | 132Sb | 138Sb |
| 52 | 133Te | 138Te |
| 53 | 134I | 138I |
| 54 | 135Xe | 138Xe |
| 55 | 136Cs | 138Cs |
| 56 | 137Ba | 138Ba |
| 57 | 138La | 138La |
| 58 | 139Ce | 138Ce |
| 59 | 140Pr | 138Pr |
| 60 | 141Nd | 138Nd |
| 61 | 142Pm | 138Pm |
| 62 | 143Sm | 138Sm |
| 63 | 144Eu | 138Eu |
| 64 | 145Gd | 138Gd |
| 65 | 146Tb | 138Tb |
| 66 | 147Dy | 138Dy |
| 67 | 148Ho | |
| 68 | 149Er | |
| 69 | 150Tm | |
| 70 | 151Yb | |
| 71 | 152Lu | |
| 72 | 153Hf | |
External data and identifiers
Last update: 2020-10-19
Perma link: https://www.chemlin.org/isotope/lanthanum-138
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