Iodine-138

Properties and data of the isotope ¹³⁸I.

Content

General Data

Radioactive Decay

Parent Nuclides

Isotones und Isobares

Literature

General data

Name of the isotope:Iodine-138; I-138Other names:Jod-138Symbol:¹³⁸I or 13853IMass number A:138 (= number of nucleons)Atomic number Z:53 (= number of protons)Neutrons N:85Isotopic mass:137.922726(6) u (atomic weight of Iodine-138)Nuclide mass:137.8936531 u (calculated nuclear mass without electrons)Mass excess:-71.98027 MeVMass defect:1.228518556 u (per nucleus)Nuclear binding energy:1144.3576638 MeV (per nucleus)
8.29244684 MeV (average binding energy per nucleon)Separation energy:S_N = 3.695(10) MeV (first neutron)
S_P = 9.965(6) MeV (first proton)Half-life:6.26(3) sDecay constant λ:0.11072638667092 s^-1Specific activity α:4.86722552878 × 10⁺²⁰ Bq g^-1
13154663591.322 Ci g^-1Spin and parity:
(nuclear angular momentum)(1-)Year of discovery:1949

Radioactive Decay

Half-life T_½ = 6.26(3) s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
β^-	¹³⁸Xe	94.54 %	7.992(7) MeV
β^-, n	¹³⁷Xe	5.46 %	2.332(6) MeV

Parent Nuclides

Direct parent isotope is: ¹³⁸Te.

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
^138mI	67.9(3) keV	1.26(16) μs	(3-)

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 85) and isobaric (same nucleon number A = 138) with Iodine-138. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

OZ	Isotone N = 85	Isobar A = 138
47	¹³²Ag
48	¹³³Cd
49	¹³⁴In
50	¹³⁵Sn	¹³⁸Sn
51	¹³⁶Sb	¹³⁸Sb
52	¹³⁷Te	¹³⁸Te
53	¹³⁸I	¹³⁸I
54	¹³⁹Xe	¹³⁸Xe
55	¹⁴⁰Cs	¹³⁸Cs
56	¹⁴¹Ba	¹³⁸Ba
57	¹⁴²La	¹³⁸La
58	¹⁴³Ce	¹³⁸Ce
59	¹⁴⁴Pr	¹³⁸Pr
60	¹⁴⁵Nd	¹³⁸Nd
61	¹⁴⁶Pm	¹³⁸Pm
62	¹⁴⁷Sm	¹³⁸Sm
63	¹⁴⁸Eu	¹³⁸Eu
64	¹⁴⁹Gd	¹³⁸Gd
65	¹⁵⁰Tb	¹³⁸Tb
66	¹⁵¹Dy	¹³⁸Dy
67	¹⁵²Ho
68	¹⁵³Er
69	¹⁵⁴Tm
70	¹⁵⁵Yb
71	¹⁵⁶Lu
72	¹⁵⁷Hf
73	¹⁵⁸Ta
74	¹⁵⁹W
75	¹⁶⁰Re
76	¹⁶¹Os