Polonium-211

Properties and data of the isotope ²¹¹Po.

Contents

General Data

Radioactive Decay

Parent Nuclides

Isotones und Isobares

Literature

Polonium-211 is a radioisotope of the chemical element polonium, which has 127 neutrons in its atomic nucleus in addition to the element-specific 84 protons; the sum of the number of these atomic nucleus building blocks results in a mass number of 211. The very short-lived, only artificially produced, unstable and thus radioactive nuclide has no practical significance; the study of ²¹¹Po is exclusively for academic purposes.

Polonium-211 was discovered in 1913 as a radioactive decay product of the isotope bismuth-211, then known as actinium C [1].

See also: List of individual Polonium isotopes (and general data sources).

General data

Name of the isotope:Polonium-211; Po-211Other names:Actinium C´Symbol:²¹¹Po or 21184PoMass number A:211 (= number of nucleons)Atomic number Z:84 (= number of protons)Neutrons N:127Nucleon pairing (Z - N):even - oddNuclear ratio (N/Z ratio):1.5119047619048 (= neutron-proton ratio)Neutron excess (N-Z):43Isotopic mass:210.9866532(13) u (atomic weight of Polonium-211)Nuclide mass:210.9405779 u (calculated nuclear mass without electrons)Mass excess:-12.43246 MeVMass defect:1.77109382 u (per nucleus)Nuclear binding energy:1649.76326677 MeV (per nucleus)
7.81878325 MeV (average binding energy per nucleon)Separation energy:S_N = 4.5508(5) MeV (first neutron)
S_P = 4.9296(9) MeV (first proton)Half-life:0.516(3) sDecay constant λ:1.3433084894573 s^-1Specific activity α:3.852187115171 × 10⁺²¹ Bq g^-1
104113165274.91 Ci g^-1Spin and parity:
(nuclear angular momentum)9/2+Magnetic dipole moment:μ(μ_N) = -1.197(85)Quadrupole moment Q:-0.77(8) barn (100 fm²)Nuclear g-factor:g_l = -0.266Year of discovery:1913

Radioactive Decay

Half-life T_½ = 0.516(3) s respectively 5.16 × 10^-1 seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
α	²⁰⁷Pb	100 %	7.5946(5) MeV	0.8978(1) MeV [0.551(23) %] 0.56965(10) MeV [0.535(20) %]

Formation and radioactive decay of polonium-211

Parent Nuclides

Direct parent isotopes are: ²¹⁵Rn, ²¹¹At, ²¹¹Bi.

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
^211m1Po	1462(5) keV	25.2(6) s	(25/2+)
^211m2Po	2135(5) keV	243(21) ns	(31/2-)
^211m3Po	4872(6) keV	2.8(7) μs	(43/2+)

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 127) and isobaric (same nucleon number A = 211) with Polonium-211. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 127	Isobar A = 211
76	²⁰³Os
77	²⁰⁴Ir
78	²⁰⁵Pt
79	²⁰⁶Au
80	²⁰⁷Hg	²¹¹Hg
81	²⁰⁸Tl	²¹¹Tl
82	²⁰⁹Pb	²¹¹Pb
83	²¹⁰Bi	²¹¹Bi
84	²¹¹Po	²¹¹Po
85	²¹²At	²¹¹At
86	²¹³Rn	²¹¹Rn
87	²¹⁴Fr	²¹¹Fr
88	²¹⁵Ra	²¹¹Ra
89	²¹⁶Ac	²¹¹Ac
90	²¹⁷Th	²¹¹Th
91	²¹⁸Pa
92	²¹⁹U
93	²²⁰Np

External data and identifiers

CAS:15735-83-8InChI Key:HZEBHPIOVYHPMT-NJFSPNSNSA-NSMILES:[211Po]PubChem:ID 6337588Adopted Levels, Gammas:NuDat 211Po

Literature and References

[1] - E. Marsden, R. H. Wilson:
Branch Product in Actinium C.
In: Nature, 92, 29, (1913), DOI 10.1038/092029b0.

[2] - J. R. Cottle, Vandana Tripathi, B. A. Brown et al.:
Complete spectroscopy of ²¹¹Po below 2.0 MeV via the (α,n) reaction.
In: Physical Review C, 95, 064323, (2017), DOI 10.1103/PhysRevC.95.064323.