Radon-220

Properties and data of the isotope ²²⁰Rn.

Contents

General Data

Radioactive Decay

Radiation emissions

Parent Nuclides

Isotones und Isobares

Literature

Radon-220 is a radioisotopüe of the element radon with mass number 220. The nuclide decays to Polonium-216 with a half-life of 55.6 seconds. Historical names of the radioisotope discovered in 1900 are thoron (symbol Tn) and emanation of thorium. The longest-lived decay product - Lead-212 - has a half-life of 10.6 hours, so any radon-220 contamination will be broken down within a week. The stable end product is Lead-208.

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

General data

Name of the isotope:Radon-220; Rn-220Other names:ThoronSymbol:²²⁰Rn or 22086RnMass number A:220 (= number of nucleons)Atomic number Z:86 (= number of protons)Neutrons N:134Nucleon pairing (Z - N):even - evenNuclear ratio (N/Z ratio):1.5581395348837 (= neutron-proton ratio)Neutron excess (N-Z):48Isotopic mass:220.0113925(19) u (atomic weight of Radon-220)Nuclide mass:219.9642203 u (calculated nuclear mass without electrons)Mass excess:10.61205 MeVMass defect:1.822658996 u (per nucleus)Nuclear binding energy:1697.79591882 MeV (per nucleus)
7.71725418 MeV (average binding energy per nucleon)Separation energy:S_N = 6.2886(23) MeV (first neutron)
S_P = 7.073(3) MeV (first proton)Cross section:σ(n.γ) = < 0.2 barn (thermal neutron capture cross-section)Half-life:55.6(1) sDecay constant λ:0.012466675909352 s^-1Specific activity α:3.412549017331 × 10⁺¹⁹ Bq g^-1
922310545.22476 Ci g^-1Spin and parity:
(nuclear angular momentum)0+Charge radius:5.6731(194) femtometer fmYear of discovery:1900

Radioactive Decay

Half-life T_½ = 55.6(1) s respectively 5.56 × 10¹ seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
α	²¹⁶Po	100 %	6.40474(10) MeV	0.54973(5) MeV 0.115 % 0.00063 MeV/Bq-s

Radon-220 alpha radiaton

E_α	I_α	dose (MeV/Bq-s)
5,747 MeV	0,114(17) %	0,0066(10)
6,28808(10) MeV	99,886(17) %	6,2809(11)

Parent Nuclides

Direct parent isotopes are: ²²⁴Ra, ²²⁰At.

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 134) and isobaric (same nucleon number A = 220) with Radon-220. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 134	Isobar A = 220
80	²¹⁴Hg
81	²¹⁵Tl
82	²¹⁶Pb	²²⁰Pb
83	²¹⁷Bi	²²⁰Bi
84	²¹⁸Po	²²⁰Po
85	²¹⁹At	²²⁰At
86	²²⁰Rn	²²⁰Rn
87	²²¹Fr	²²⁰Fr
88	²²²Ra	²²⁰Ra
89	²²³Ac	²²⁰Ac
90	²²⁴Th	²²⁰Th
91	²²⁵Pa	²²⁰Pa
92	²²⁶U	²²⁰U
93	²²⁷Np	²²⁰Np
94	²²⁸Pu
95	²²⁹Am

External data and identifiers

CAS:22481-48-7InChI Key:SYUHGPGVQRZVTB-YPZZEJLDSA-NSMILES:[220Rn]PubChem:ID 62761Adopted Levels, Gammas:NuDat 220Rn

Literature and References

[1] - Shinji Tokonami:
Characteristics of Thoron (²²⁰Rn) and Its Progeny in the Indoor Environment.
In: International Journal of Environmental Research and Public Health, 17(23), 8769, (2020), DOI 10.3390/ijerph17238769.