Gadolinium-138

Properties and data of the isotope ¹³⁸Gd.

Content

General data

Name of the isotope:Gadolinium-138; Gd-138Symbol:¹³⁸Gd or 13864GdMass number A:138 (= number of nucleons)Atomic number Z:64 (= number of protons)Neutrons N:74Isotopic mass:137.94010(21) u (atomic weight of Gadolinium-138)Nuclide mass:137.9049937 u (calculated nuclear mass without electrons)Mass excess:-55.79649 MeVMass defect:1.201905832 u (per nucleus)Nuclear binding energy:1119.56807107 MeV (per nucleus)
8.11281211 MeV (average binding energy per nucleon)Separation energy:S_N = 12.66(36) MeV (first neutron)
S_P = 2.94(20) MeV (first proton)Half-life:4.7(9) sDecay constant λ:0.14747812352339 s^-1Specific activity α:6.48273017238 × 10⁺²⁰ Bq g^-1
17520892357.803 Ci g^-1Spin and parity:
(nuclear angular momentum)0+Year of discovery:1985

Radioactive Decay

Half-life T_½ = 4.7(9) s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
EE β⁺	¹³⁸Eu	100 %	5.95(20) MeV

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 74) and isobaric (same nucleon number A = 138) with Gadolinium-138. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

OZ	Isotone N = 74	Isobar A = 138
41	¹¹⁵Nb
42	¹¹⁶Mo
43	¹¹⁷Tc
44	¹¹⁸Ru
45	¹¹⁹Rh
46	¹²⁰Pd
47	¹²¹Ag
48	¹²²Cd
49	¹²³In
50	¹²⁴Sn	¹³⁸Sn
51	¹²⁵Sb	¹³⁸Sb
52	¹²⁶Te	¹³⁸Te
53	¹²⁷I	¹³⁸I
54	¹²⁸Xe	¹³⁸Xe
55	¹²⁹Cs	¹³⁸Cs
56	¹³⁰Ba	¹³⁸Ba
57	¹³¹La	¹³⁸La
58	¹³²Ce	¹³⁸Ce
59	¹³³Pr	¹³⁸Pr
60	¹³⁴Nd	¹³⁸Nd
61	¹³⁵Pm	¹³⁸Pm
62	¹³⁶Sm	¹³⁸Sm
63	¹³⁷Eu	¹³⁸Eu
64	¹³⁸Gd	¹³⁸Gd
65	¹³⁹Tb	¹³⁸Tb
66	¹⁴⁰Dy	¹³⁸Dy
67	¹⁴¹Ho