Polonium-207

Properties and data of the isotope ²⁰⁷Po.

Content

General data

Name of the isotope:Polonium-207; Po-207Symbol: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-207)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)Separation energy:S_N = 7.028(8) MeV (first neutron)
S_P = 4.406(10) MeV (first proton)Half-life:5.80(2) hDecay constant λ:3.319670404980 × 10^-5 s^-1Specific activity α:9.704622712308 × 10⁺¹⁶ Bq g^-1
2622871.0033267 Ci g^-1Spin and parity:
(nuclear angular momentum)5/2-Magnetic dipole moment:μ(μ_N) = + 0.79(6)Quadrupole moment Q:+ 0.28 barn (100 fm²)Nuclear g-factor:g_l = 0.316Charge radius:5.5501(177) femtometer fmYear of discovery:1947

Radioactive Decay

Half-life T_½ = 5.80(2) h (hours) respectively 2.088 × 10⁴ seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
α	²⁰³Pb	0.021(2) %	5.2159(25) MeV
EE/β⁺	²⁰⁷Bi	99.979(2) %	2.909(7) MeV

Parent Nuclides

Direct parent isotopes are: ²¹¹Rn, ²⁰⁷At.

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
^207m1Po	68.557(14) keV	205(10) ns	1/2-
^207m2Po	1115.076(17) keV	49(4) μs	13/2+
^207m3Po		2.79(8) s	19/2-

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-207. 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