Cesium-136

Properties and data of the isotope ¹³⁶Cs.

Content

General data

Name of the isotope:Cesium-136; Cs-136Symbol:¹³⁶Cs or 13655CsMass number A:136 (= number of nucleons)Atomic number Z:55 (= number of protons)Neutrons N:81Isotopic mass:135.9073116(20) u (atomic weight of Cesium-136)Nuclide mass:135.8771417 u (calculated nuclear mass without electrons)Mass excess:-86.33869 MeVMass defect:1.224923356 u (per nucleus)Nuclear binding energy:1141.00875657 MeV (per nucleus)
8.38977027 MeV (average binding energy per nucleon)Separation energy:S_N = 6.8284(21) MeV (first neutron)
S_P = 7.215(4) MeV (first proton)Half-life:13.01(5) dDecay constant λ:6.166438748682 × 10^-7 s^-1Specific activity α:2.75075279620 × 10⁺¹⁵ Bq g^-1
74344.670167649 Ci g^-1Spin and parity:
(nuclear angular momentum)5+Magnetic dipole moment:μ(μ_N) = + 3.705(15)Quadrupole moment Q:+0.225 barn (100 fm²)Nuclear g-factor:g_l = 0.741Charge radius:4.8059(52) femtometer fmYear of discovery:1951

Radioactive Decay

Half-life T_½ = 13.01(5) d respectively 1.124064 × 10⁶ seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
β^-	¹³⁶Ba	100 %	2.5482(19) MeV

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
^136mCs	517.9(1) keV	17.5(2) s	8-

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 81) and isobaric (same nucleon number A = 136) with Cesium-136. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

OZ	Isotone N = 81	Isobar A = 136
45	¹²⁶Rh
46	¹²⁷Pd
47	¹²⁸Ag
48	¹²⁹Cd
49	¹³⁰In	¹³⁶In
50	¹³¹Sn	¹³⁶Sn
51	¹³²Sb	¹³⁶Sb
52	¹³³Te	¹³⁶Te
53	¹³⁴I	¹³⁶I
54	¹³⁵Xe	¹³⁶Xe
55	¹³⁶Cs	¹³⁶Cs
56	¹³⁷Ba	¹³⁶Ba
57	¹³⁸La	¹³⁶La
58	¹³⁹Ce	¹³⁶Ce
59	¹⁴⁰Pr	¹³⁶Pr
60	¹⁴¹Nd	¹³⁶Nd
61	¹⁴²Pm	¹³⁶Pm
62	¹⁴³Sm	¹³⁶Sm
63	¹⁴⁴Eu	¹³⁶Eu
64	¹⁴⁵Gd	¹³⁶Gd
65	¹⁴⁶Tb	¹³⁶Tb
66	¹⁴⁷Dy
67	¹⁴⁸Ho
68	¹⁴⁹Er
69	¹⁵⁰Tm
70	¹⁵¹Yb
71	¹⁵²Lu
72	¹⁵³Hf