Lanthanum-124

Properties and data of the isotope ¹²⁴La.

Contents

General data

Name of the isotope:Lanthanum-124; La-124Symbol:¹²⁴La or 12457LaMass number A:124 (= number of nucleons)Atomic number Z:57 (= number of protons)Neutrons N:67Isotopic mass:123.92457(6) u (atomic weight of Lanthanum-124)Nuclide mass:123.8933031 u (calculated nuclear mass without electrons)Mass excess:-70.26259 MeVMass defect:1.102006196 u (per nucleus)Nuclear binding energy:1026.51215954 MeV (per nucleus)
8.27832387 MeV (average binding energy per nucleon)Separation energy:S_N = 9.68(20) MeV (first neutron)
S_P = 1.89(6) MeV (first proton)Half-life:21(4) sDecay constant λ:0.033007008598093 s^-1Specific activity α:1.616039472706 × 10⁺²⁰ Bq g^-1
4367674250.5573 Ci g^-1Spin and parity:
(nuclear angular momentum)8-Year of discovery:1978

Radioactive Decay

Half-life T_½ = 21(4) s respectively 2.1 × 10¹ seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
EC/β⁺	¹²⁴Ba	100 %	8.83(6) MeV

Parent Nuclides

Direct parent isotope is: ¹²⁴Ce.

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
^124mLa	100 keV	29.21(17) s	(8-)

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 67) and isobaric (same nucleon number A = 124) with Lanthanum-124. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 67	Isobar A = 124
38	¹⁰⁵Sr
39	¹⁰⁶Y
40	¹⁰⁷Zr
41	¹⁰⁸Nb
42	¹⁰⁹Mo
43	¹¹⁰Tc
44	¹¹¹Ru	¹²⁴Ru
45	¹¹²Rh	¹²⁴Rh
46	¹¹³Pd	¹²⁴Pd
47	¹¹⁴Ag	¹²⁴Ag
48	¹¹⁵Cd	¹²⁴Cd
49	¹¹⁶In	¹²⁴In
50	¹¹⁷Sn	¹²⁴Sn
51	¹¹⁸Sb	¹²⁴Sb
52	¹¹⁹Te	¹²⁴Te
53	¹²⁰I	¹²⁴I
54	¹²¹Xe	¹²⁴Xe
55	¹²²Cs	¹²⁴Cs
56	¹²³Ba	¹²⁴Ba
57	¹²⁴La	¹²⁴La
58	¹²⁵Ce	¹²⁴Ce
59	¹²⁶Pr	¹²⁴Pr
60	¹²⁷Nd	¹²⁴Nd
61	¹²⁸Pm
62	¹²⁹Sm
63	¹³⁰Eu