Xenon-138

Properties and data of the isotope ¹³⁸Xe.

Content

General data

Name of the isotope:Xenon-138; Xe-138Symbol:¹³⁸Xe or 13854XeMass number A:138 (= number of nucleons)Atomic number Z:54 (= number of protons)Neutrons N:84Isotopic mass:137.914146(3) u (atomic weight of Xenon-138)Nuclide mass:137.8845246 u (calculated nuclear mass without electrons)Mass excess:-79.97249 MeVMass defect:1.236258672 u (per nucleus)Nuclear binding energy:1151.56753542 MeV (per nucleus)
8.34469229 MeV (average binding energy per nucleon)Separation energy:S_N = 5.6601(28) MeV (first neutron)
S_P = 10.905(9) MeV (first proton)Half-life:14.14(7) minDecay constant λ:0.00081700516331912 s^-1Specific activity α:3.591328596206 × 10⁺¹⁸ Bq g^-1
97062935.032619 Ci g^-1Spin and parity:
(nuclear angular momentum)0+Charge radius:4.8279(79) femtometer fmYear of discovery:1943

Radioactive Decay

Half-life T_½ = 14.14(7) min (minutes) respectively 8.484 × 10² seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
β^-	¹³⁸Cs	100 %	2.915(10) MeV

Parent Nuclides

Direct parent isotopes are: ¹³⁸I, ¹³⁹I, ²⁴⁸Cm, ²⁵²Cf.

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 84) and isobaric (same nucleon number A = 138) with Xenon-138. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

OZ	Isotone N = 84	Isobar A = 138
47	¹³¹Ag
48	¹³²Cd
49	¹³³In
50	¹³⁴Sn	¹³⁸Sn
51	¹³⁵Sb	¹³⁸Sb
52	¹³⁶Te	¹³⁸Te
53	¹³⁷I	¹³⁸I
54	¹³⁸Xe	¹³⁸Xe
55	¹³⁹Cs	¹³⁸Cs
56	¹⁴⁰Ba	¹³⁸Ba
57	¹⁴¹La	¹³⁸La
58	¹⁴²Ce	¹³⁸Ce
59	¹⁴³Pr	¹³⁸Pr
60	¹⁴⁴Nd	¹³⁸Nd
61	¹⁴⁵Pm	¹³⁸Pm
62	¹⁴⁶Sm	¹³⁸Sm
63	¹⁴⁷Eu	¹³⁸Eu
64	¹⁴⁸Gd	¹³⁸Gd
65	¹⁴⁹Tb	¹³⁸Tb
66	¹⁵⁰Dy	¹³⁸Dy
67	¹⁵¹Ho
68	¹⁵²Er
69	¹⁵³Tm
70	¹⁵⁴Yb
71	¹⁵⁵Lu
72	¹⁵⁶Hf
73	¹⁵⁷Ta
74	¹⁵⁸W
75	¹⁵⁹Re