Lanthanum-137

Properties and data of the isotope ¹³⁷La.

Contents

General data

Name of the isotope:Lanthanum-137; La-137Symbol:¹³⁷La or 13757LaMass number A:137 (= number of nucleons)Atomic number Z:57 (= number of protons)Neutrons N:80Isotopic mass:136.9064506(18) u (atomic weight of Lanthanum-137)Nuclide mass:136.8751837 u (calculated nuclear mass without electrons)Mass excess:-87.1407 MeVMass defect:1.232769504 u (per nucleus)Nuclear binding energy:1148.31739636 MeV (per nucleus)
8.38187881 MeV (average binding energy per nucleon)Separation energy:S_N = 9.17(5) MeV (first neutron)
S_P = 5.5427(16) MeV (first proton)Half-life:60000 aDecay constant λ:3.663258818281 × 10^-13 s^-1Specific activity α:1622107397.8012 Bq g^-1
0.043840740481114 Ci g^-1Spin and parity:
(nuclear angular momentum)7/2+Magnetic dipole moment:μ(μ_N) = +2.696(6)Quadrupole moment Q:+0.21(3) barn (100 fm²)Nuclear g-factor:g_l = 0.77028571428571Charge radius:4.8496(53) femtometer fmYear of discovery:1948

Radioactive Decay

Half-life T_½ = 60000 a respectively 1.89216 × 10¹² seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
EC	¹³⁷Ba	100 %	0.5805(17) MeV

Parent Nuclides

Direct parent isotope is: ¹³⁷Ce.

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 80) and isobaric (same nucleon number A = 137) with Lanthanum-137. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 80	Isobar A = 137
44	¹²⁴Ru
45	¹²⁵Rh
46	¹²⁶Pd
47	¹²⁷Ag
48	¹²⁸Cd
49	¹²⁹In	¹³⁷In
50	¹³⁰Sn	¹³⁷Sn
51	¹³¹Sb	¹³⁷Sb
52	¹³²Te	¹³⁷Te
53	¹³³I	¹³⁷I
54	¹³⁴Xe	¹³⁷Xe
55	¹³⁵Cs	¹³⁷Cs
56	¹³⁶Ba	¹³⁷Ba
57	¹³⁷La	¹³⁷La
58	¹³⁸Ce	¹³⁷Ce
59	¹³⁹Pr	¹³⁷Pr
60	¹⁴⁰Nd	¹³⁷Nd
61	¹⁴¹Pm	¹³⁷Pm
62	¹⁴²Sm	¹³⁷Sm
63	¹⁴³Eu	¹³⁷Eu
64	¹⁴⁴Gd	¹³⁷Gd
65	¹⁴⁵Tb	¹³⁷Tb
66	¹⁴⁶Dy
67	¹⁴⁷Ho
68	¹⁴⁸Er
69	¹⁴⁹Tm
70	¹⁵⁰Yb
71	¹⁵¹Lu