Europium-137

Properties and data of the isotope ¹³⁷Eu.

Contents

General data

Name of the isotope:Europium-137; Eu-137Symbol:¹³⁷Eu or 13763EuMass number A:137 (= number of nucleons)Atomic number Z:63 (= number of protons)Neutrons N:74Isotopic mass:136.935431(5) u (atomic weight of Europium-137)Nuclide mass:136.9008732 u (calculated nuclear mass without electrons)Mass excess:-60.14564 MeVMass defect:1.1987498 u (per nucleus)Nuclear binding energy:1116.6282462 MeV (per nucleus)
8.15057114 MeV (average binding energy per nucleon)Separation energy:S_N = 11.97(20) MeV (first neutron)
S_P = 0.624(13) MeV (first proton)Half-life:11(2) sDecay constant λ:0.063013380050904 s^-1Specific activity α:2.790260667112 × 10⁺²⁰ Bq g^-1
7541245046.2495 Ci g^-1Spin and parity:
(nuclear angular momentum)(11/2-)Charge radius:4.9762(95) femtometer fmYear of discovery:1982

Radioactive Decay

Half-life T_½ = 11(2) s respectively 1.1 × 10¹ seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
EE/β⁺	¹³⁷Sm	100 %	7.88(4) 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 = 137) with Europium-137. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

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