Astatine-196m

Properties and data of the isotope ¹⁹⁶At.

Content

General data

Name of the isotope:Astatine-196m; At-196mSymbol:¹⁹⁶At or 19685AtMass number A:196 (= number of nucleons)Atomic number Z:85 (= number of protons)Neutrons N:111Isotopic mass:195.99580(3) u (atomic weight of Astatine-196m)
Excitation energy: 157.9(1) keVNuclide mass:195.9491763 u (calculated nuclear mass without electrons)Mass excess:-3.91227 MeVMass defect:1.631133396 u (per nucleus)Nuclear binding energy:1519.39097157 MeV (per nucleus)
7.75199475 MeV (average binding energy per nucleon)Half-life:11(2) μsDecay constant λ:63013.380050904 s^-1Specific activity α:1.946027952447 × 10⁺²⁶ Bq g^-1
5.259535006615 × 10⁺¹⁵ Ci g^-1Spin and parity:
(nuclear angular momentum)(5+)

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
¹⁹⁶At		388(7) ms	(3+)

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 111) and isobaric (same nucleon number A = 196) with Astatine-196m. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

OZ	Isotone N = 111	Isobar A = 196
70	¹⁸¹Yb
71	¹⁸²Lu
72	¹⁸³Hf
73	¹⁸⁴Ta
74	¹⁸⁵W	¹⁹⁶W
75	¹⁸⁶Re	¹⁹⁶Re
76	¹⁸⁷Os	¹⁹⁶Os
77	¹⁸⁸Ir	¹⁹⁶Ir
78	¹⁸⁹Pt	¹⁹⁶Pt
79	¹⁹⁰Au	¹⁹⁶Au
80	¹⁹¹Hg	¹⁹⁶Hg
81	¹⁹²Tl	¹⁹⁶Tl
82	¹⁹³Pb	¹⁹⁶Pb
83	¹⁹⁴Bi	¹⁹⁶Bi
84	¹⁹⁵Po	¹⁹⁶Po
85	¹⁹⁶At	¹⁹⁶At
86	¹⁹⁷Rn	¹⁹⁶Rn