Tantalum-156m

Properties and data of the isotope ^156mTa.

Contents

General data

Name of the isotope:Tantalum-156m; Ta-156mSymbol:^156mTa or 156m73TaMass number A:156 (= number of nucleons)Atomic number Z:73 (= number of protons)Neutrons N:83Isotopic mass:155.97224(32) u (atomic weight of Tantalum-156m)
Excitation energy: 102(7) keVNuclide mass:155.9321976 u (calculated nuclear mass without electrons)Mass excess:-25.85827 MeVMass defect:1.318175364 u (per nucleus)Nuclear binding energy:1227.87244251 MeV (per nucleus)
7.8709772 MeV (average binding energy per nucleon)Half-life:0.36(4) sDecay constant λ:1.9254088348887 s^-1Specific activity α:7.480698849462 × 10⁺²¹ Bq g^-1
202181049985.47 Ci g^-1Spin and parity:
(nuclear angular momentum)9+

Radioactive Decay

Half-life T_½ = 0.36(4) s respectively 3.6 × 10^-1 seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
EC/β⁺	¹⁵⁶Hf	95.8(9) %
p	¹⁵⁵Hf	4.2(9) %

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
¹⁵⁶Ta		333 ms	(2-)

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 83) and isobaric (same nucleon number A = 156) with Tantalum-156m. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 83	Isobar A = 156
46	¹²⁹Pd
47	¹³⁰Ag
48	¹³¹Cd
49	¹³²In
50	¹³³Sn
51	¹³⁴Sb
52	¹³⁵Te
53	¹³⁶I
54	¹³⁷Xe
55	¹³⁸Cs
56	¹³⁹Ba
57	¹⁴⁰La	¹⁵⁶La
58	¹⁴¹Ce	¹⁵⁶Ce
59	¹⁴²Pr	¹⁵⁶Pr
60	¹⁴³Nd	¹⁵⁶Nd
61	¹⁴⁴Pm	¹⁵⁶Pm
62	¹⁴⁵Sm	¹⁵⁶Sm
63	¹⁴⁶Eu	¹⁵⁶Eu
64	¹⁴⁷Gd	¹⁵⁶Gd
65	¹⁴⁸Tb	¹⁵⁶Tb
66	¹⁴⁹Dy	¹⁵⁶Dy
67	¹⁵⁰Ho	¹⁵⁶Ho
68	¹⁵¹Er	¹⁵⁶Er
69	¹⁵²Tm	¹⁵⁶Tm
70	¹⁵³Yb	¹⁵⁶Yb
71	¹⁵⁴Lu	¹⁵⁶Lu
72	¹⁵⁵Hf	¹⁵⁶Hf
73	¹⁵⁶Ta	¹⁵⁶Ta
74	¹⁵⁷W	¹⁵⁶W