Lanthanum-135

Properties and data of the isotope ¹³⁵La.

Content

General data

Name of the isotope:Lanthanum-135; La-135Symbol:¹³⁵La or 13557LaMass number A:135 (= number of nucleons)Atomic number Z:57 (= number of protons)Neutrons N:78Isotopic mass:134.906985(10) u (atomic weight of Lanthanum-135)Nuclide mass:134.8757181 u (calculated nuclear mass without electrons)Mass excess:-86.64291 MeVMass defect:1.214905272 u (per nucleus)Nuclear binding energy:1131.67697144 MeV (per nucleus)
8.38279238 MeV (average binding energy per nucleon)Separation energy:S_N = 9.496(22) MeV (first neutron)
S_P = 4.982(9) MeV (first proton)Half-life:19.5(2) hDecay constant λ:9.873891460967 × 10^-6 s^-1Specific activity α:4.437460090572 × 10⁺¹⁶ Bq g^-1
1199313.5379926 Ci g^-1Spin and parity:
(nuclear angular momentum)5/2+Magnetic dipole moment:μ(μ_N) = +3.70(9)Quadrupole moment Q:-40.0 barn (100 fm²)Nuclear g-factor:g_l = 1.48Charge radius:4.8488(60) femtometer fmYear of discovery:1948

Radioactive Decay

Half-life T_½ = 19.5(2) h (hours) respectively 7.0200 × 10⁴ seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
EE/β⁺	¹³⁵Ba	100 %	1.207(9) MeV

Parent Nuclides

Direct parent isotope is: ¹³⁵Ce.

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 78) and isobaric (same nucleon number A = 135) with Lanthanum-135. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

OZ	Isotone N = 78	Isobar A = 135
43	¹²¹Tc
44	¹²²Ru
45	¹²³Rh
46	¹²⁴Pd
47	¹²⁵Ag
48	¹²⁶Cd
49	¹²⁷In	¹³⁵In
50	¹²⁸Sn	¹³⁵Sn
51	¹²⁹Sb	¹³⁵Sb
52	¹³⁰Te	¹³⁵Te
53	¹³¹I	¹³⁵I
54	¹³²Xe	¹³⁵Xe
55	¹³³Cs	¹³⁵Cs
56	¹³⁴Ba	¹³⁵Ba
57	¹³⁵La	¹³⁵La
58	¹³⁶Ce	¹³⁵Ce
59	¹³⁷Pr	¹³⁵Pr
60	¹³⁸Nd	¹³⁵Nd
61	¹³⁹Pm	¹³⁵Pm
62	¹⁴⁰Sm	¹³⁵Sm
63	¹⁴¹Eu	¹³⁵Eu
64	¹⁴²Gd	¹³⁵Gd
65	¹⁴³Tb	¹³⁵Tb
66	¹⁴⁴Dy
67	¹⁴⁵Ho
68	¹⁴⁶Er
69	¹⁴⁷Tm
70	¹⁴⁸Yb
71	¹⁴⁹Lu