Polonium-209

Properties and data of the isotope ²⁰⁹Po.

Contents

General Data

Radioactive Decay

Parent Nuclides

NMR Data

Isotones und Isobares

General data

Name of the isotope:Polonium-209; Po-209Symbol:²⁰⁹Po or 20984PoMass number A:209 (= number of nucleons)Atomic number Z:84 (= number of protons)Neutrons N:125Isotopic mass:208.9824304(19) u (atomic weight of Polonium-209)Nuclide mass:208.9363551 u (calculated nuclear mass without electrons)Mass excess:-16.36598 MeVMass defect:1.757986788 u (per nucleus)Nuclear binding energy:1637.5541451 MeV (per nucleus)
7.8351873 MeV (average binding energy per nucleon)Separation energy:S_N = 6.9681(19) MeV (first neutron)
S_P = 4.7848(24) MeV (first proton)Half-life:124(3) aDecay constant λ:1.772754937493 × 10^-10 s^-1Specific activity α:513258651141.06 Bq g^-1
13.871855436245 Ci g^-1Spin and parity:
(nuclear angular momentum)1/2-Magnetic dipole moment:μ(μ_N) = + 0.68(8)Charge radius:5.5628(176) femtometer fmYear of discovery:1949

Radioactive Decay

Half-life T_½ = 124(3) a respectively 3.91 × 10⁹ seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
α	²⁰⁵Pb	99.546(7) %	4.9792(14) MeV
EC/β⁺	²⁰⁹Bi	0.454(7) %	1.8926(22) MeV

Parent Nuclides

Direct parent isotopes are: ²¹³Rn, ²⁰⁹At.

NMR data

Nuclear magnetic properties of the NMR active Nuclide ²⁰⁹Po

Isotope:²⁰⁹Po-NMRQuantity:SpurenSpin:1/2-Nuclearmagnetic moment
μ/μ_N:+ 0.68(8)Gyromagnetic ratio γ:7.4 · 10⁷ rad T^-1 s^-1Nuclear g-factor:g_l = 1.36Resonance frequency:v₀ = 11.7 at 1 TRelative Sensitivity:0.02096 (H₀ = const.)
0.2757 (v₀ = const.)
[related to ¹H = 1.000]

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
^209mPo		119(4) ns	31/2-

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 125) and isobaric (same nucleon number A = 209) with Polonium-209. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 125	Isobar A = 209
76	²⁰¹Os
77	²⁰²Ir
78	²⁰³Pt
79	²⁰⁴Au	²⁰⁹Au
80	²⁰⁵Hg	²⁰⁹Hg
81	²⁰⁶Tl	²⁰⁹Tl
82	²⁰⁷Pb	²⁰⁹Pb
83	²⁰⁸Bi	²⁰⁹Bi
84	²⁰⁹Po	²⁰⁹Po
85	²¹⁰At	²⁰⁹At
86	²¹¹Rn	²⁰⁹Rn
87	²¹²Fr	²⁰⁹Fr
88	²¹³Ra	²⁰⁹Ra
89	²¹⁴Ac	²⁰⁹Ac
90	²¹⁵Th	²⁰⁹Th
91	²¹⁶Pa
92	²¹⁷U