Barium-137m2

Properties and data of the isotope ^137m2Ba.

Contents

See also: List of individual Barium isotopes (and general data sources).

General data

Name of the isotope:Barium-137m2; Ba-137m2Symbol:^137m2Ba or 137m256BaMass number A:137 (= number of nucleons)Atomic number Z:56 (= number of protons)Neutrons N:81Nucleon pairing (Z - N):even - oddNuclear ratio (N/Z ratio):1.4464285714286 (= neutron-proton ratio)Neutron excess (N-Z):25Excitation energy:2349.1(5) keVIsotopic mass:136.905827(2) u (atomic weight of Barium-137m2)Nuclide mass:136.8751086 u (calculated nuclear mass without electrons)Mass excess:-87.72158 MeVMass defect:1.234232988 u (per nucleus)Nuclear binding energy:1149.68062292 MeV (per nucleus)
8.39182936 MeV (average binding energy per nucleon)Half-life:0.59(10) μsDecay constant λ:1174825.7297626 s^-1Specific activity α:5.202180904785 × 10⁺²⁷ Bq g^-1
1.405994839131 × 10⁺¹⁷ Ci g^-1Spin and parity:
(nuclear angular momentum)(17/2-)

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
¹³⁷Ba		stable	3/2+
^137mBa	661.659(3) keV	2.552(1) min	11/2-

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 81) and isobaric (same nucleon number A = 137) with Barium-137m2. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 81	Isobar A = 137
45	¹²⁶Rh
46	¹²⁷Pd
47	¹²⁸Ag
48	¹²⁹Cd
49	¹³⁰In	¹³⁷In
50	¹³¹Sn	¹³⁷Sn
51	¹³²Sb	¹³⁷Sb
52	¹³³Te	¹³⁷Te
53	¹³⁴I	¹³⁷I
54	¹³⁵Xe	¹³⁷Xe
55	¹³⁶Cs	¹³⁷Cs
56	¹³⁷Ba	¹³⁷Ba
57	¹³⁸La	¹³⁷La
58	¹³⁹Ce	¹³⁷Ce
59	¹⁴⁰Pr	¹³⁷Pr
60	¹⁴¹Nd	¹³⁷Nd
61	¹⁴²Pm	¹³⁷Pm
62	¹⁴³Sm	¹³⁷Sm
63	¹⁴⁴Eu	¹³⁷Eu
64	¹⁴⁵Gd	¹³⁷Gd
65	¹⁴⁶Tb	¹³⁷Tb
66	¹⁴⁷Dy
67	¹⁴⁸Ho
68	¹⁴⁹Er
69	¹⁵⁰Tm
70	¹⁵¹Yb
71	¹⁵²Lu
72	¹⁵³Hf