Polonium-207m3

Properties and data of the isotope ²⁰⁷Po.

Content

General data

Name of the isotope:Polonium-207m3; Po-207m3Symbol:²⁰⁷Po or 20784PoMass number A:207 (= number of nucleons)Atomic number Z:84 (= number of protons)Neutrons N:123Isotopic mass:206.981593(7) u (atomic weight of Polonium-207m3)Nuclide mass:206.9355177 u (calculated nuclear mass without electrons)Mass excess:-17.14601 MeVMass defect:1.741494356 u (per nucleus)Nuclear binding energy:1622.19154365 MeV (per nucleus)
7.83667412 MeV (average binding energy per nucleon)Half-life:2.79(8) sDecay constant λ:0.24843984966306 s^-1Specific activity α:7.262814416953 × 10⁺²⁰ Bq g^-1
19629228153.929 Ci g^-1Spin and parity:
(nuclear angular momentum)19/2-

Radioactive Decay

Half-life T_½ = 2.79(8) s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
Iso	²⁰⁷Po	100 %

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
²⁰⁷Po		5.80(2) h	5/2-
^207m1Po	68.557(14) keV	205(10) ns	1/2-
^207m2Po	1115.076(17) keV	49(4) μs	13/2+

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 123) and isobaric (same nucleon number A = 207) with Polonium-207m3. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

OZ	Isotone N = 123	Isobar A = 207
74	¹⁹⁷W
75	¹⁹⁸Re
76	¹⁹⁹Os
77	²⁰⁰Ir
78	²⁰¹Pt	²⁰⁷Pt
79	²⁰²Au	²⁰⁷Au
80	²⁰³Hg	²⁰⁷Hg
81	²⁰⁴Tl	²⁰⁷Tl
82	²⁰⁵Pb	²⁰⁷Pb
83	²⁰⁶Bi	²⁰⁷Bi
84	²⁰⁷Po	²⁰⁷Po
85	²⁰⁸At	²⁰⁷At
86	²⁰⁹Rn	²⁰⁷Rn
87	²¹⁰Fr	²⁰⁷Fr
88	²¹¹Ra	²⁰⁷Ra
89	²¹²Ac	²⁰⁷Ac
90	²¹³Th	²⁰⁷Th
91	²¹⁴Pa
92	²¹⁵U