Polonium-220

Properties and data of the isotope ²²⁰Po.

Contents

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

General data

Name of the isotope:Polonium-220; Po-220Symbol:²²⁰Po or 22084PoMass number A:220 (= number of nucleons)Atomic number Z:84 (= number of protons)Neutrons N:136Nucleon pairing (Z - N):even - evenNuclear ratio (N/Z ratio):1.6190476190476 (= neutron-proton ratio)Neutron excess (N-Z):52Isotopic mass:220.016386(19) u (atomic weight of Polonium-220)Nuclide mass:219.9703107 u (calculated nuclear mass without electrons)Mass excess:15.26346 MeVMass defect:1.819345264 u (per nucleus)Nuclear binding energy:1694.70919734 MeV (per nucleus)
7.70322362 MeV (average binding energy per nucleon)Separation energy:S_N = 5.489(24) MeV (first neutron)
S_P = 8.31(20) MeV (first proton)Half-life:300 nsDecay constant λ:2310490.6018665 s^-1Specific activity α:6.324590845454 × 10⁺²⁷ Bq g^-1
1.709348877149 × 10⁺¹⁷ Ci g^-1Spin and parity:
(nuclear angular momentum)0+Year of discovery:1998

Radioactive Decay

Half-life T_½ = 300 ns respectively 3.0 × 10^-7 seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
β^-	²²⁰At	?	0.888(23) MeV

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 136) and isobaric (same nucleon number A = 220) with Polonium-220. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 136	Isobar A = 220
80	²¹⁶Hg
81	²¹⁷Tl
82	²¹⁸Pb	²²⁰Pb
83	²¹⁹Bi	²²⁰Bi
84	²²⁰Po	²²⁰Po
85	²²¹At	²²⁰At
86	²²²Rn	²²⁰Rn
87	²²³Fr	²²⁰Fr
88	²²⁴Ra	²²⁰Ra
89	²²⁵Ac	²²⁰Ac
90	²²⁶Th	²²⁰Th
91	²²⁷Pa	²²⁰Pa
92	²²⁸U	²²⁰U
93	²²⁹Np	²²⁰Np
94	²³⁰Pu
95	²³¹Am
96	²³²Cm
97	²³³Bk