Barium-138

Properties and data of the isotope ¹³⁸Ba.

Content

General data

Name of the isotope:Barium-138; Ba-138Symbol:¹³⁸Ba or 13856BaMass number A:138 (= number of nucleons)Atomic number Z:56 (= number of protons)Neutrons N:82Isotopic mass:137.905247(2) u (atomic weight of Barium-138)Nuclide mass:137.8745286 u (calculated nuclear mass without electrons)Mass excess:-88.26185 MeVMass defect:1.243477904 u (per nucleus)Nuclear binding energy:1158.29220671 MeV (per nucleus)
8.39342179 MeV (average binding energy per nucleon)Separation energy:S_N = 8.61172(4) MeV (first neutron)
S_P = 9.00500(18) MeV (first proton)Half-life:stableSpin and parity:
(nuclear angular momentum)0+Quadrupole moment Q:0.236(3) barn (100 fm²)Charge radius:4.8378(46) femtometer fmYear of discovery:1925

Parent Nuclides

Direct parent isotopes are: ¹³⁸La, ¹³⁸Cs, ¹³⁸Ce.

Occurrence

Comparison of the natural Barium isotopes including isotopic abundance (mole fraction of the isotope mixture in percent):

	Atomic Mass m_a	Quantity	Half-life	Spin
Barium Isotopic mixture	137.327 u	100 %
Isotope ¹³⁰Ba	129.90632(2) u	0.11(1) %	1.6 × 10²¹ a	0+
Isotope ¹³²Ba	131.9050611(11) u	0.10(1) %	stable	0+
Isotope ¹³⁴Ba	133.904508(2) u	2.42(15) %	stable	0+
Isotope ¹³⁵Ba	134.905688(2) u	6.59(10) %	stable	3/2+
Isotope ¹³⁶Ba	135.904576(2) u	7.85(24) %	stable	0+
Isotope ¹³⁷Ba	136.905827(2) u	11.23(23) %	stable	3/2+
Isotope ¹³⁸Ba	137.905247(2) u	71.70(29) %	stable	0+

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
^138mBa	2090.536(21) keV	0.85(10) μs	6+

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 82) and isobaric (same nucleon number A = 138) with Barium-138. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 82	Isobar A = 138
45	¹²⁷Rh
46	¹²⁸Pd
47	¹²⁹Ag
48	¹³⁰Cd
49	¹³¹In
50	¹³²Sn	¹³⁸Sn
51	¹³³Sb	¹³⁸Sb
52	¹³⁴Te	¹³⁸Te
53	¹³⁵I	¹³⁸I
54	¹³⁶Xe	¹³⁸Xe
55	¹³⁷Cs	¹³⁸Cs
56	¹³⁸Ba	¹³⁸Ba
57	¹³⁹La	¹³⁸La
58	¹⁴⁰Ce	¹³⁸Ce
59	¹⁴¹Pr	¹³⁸Pr
60	¹⁴²Nd	¹³⁸Nd
61	¹⁴³Pm	¹³⁸Pm
62	¹⁴⁴Sm	¹³⁸Sm
63	¹⁴⁵Eu	¹³⁸Eu
64	¹⁴⁶Gd	¹³⁸Gd
65	¹⁴⁷Tb	¹³⁸Tb
66	¹⁴⁸Dy	¹³⁸Dy
67	¹⁴⁹Ho
68	¹⁵⁰Er
69	¹⁵¹Tm
70	¹⁵²Yb
71	¹⁵³Lu
72	¹⁵⁴Hf
73	¹⁵⁵Ta
74	¹⁵⁶W