Radon-218

Properties and data of the isotope ²¹⁸Rn.

Contents

General Data

Radioactive Decay

Parent Nuclides

Isotones und Isobares

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

General data

Name of the isotope:Radon-218; Rn-218Symbol:²¹⁸Rn or 21886RnMass number A:218 (= number of nucleons)Atomic number Z:86 (= number of protons)Neutrons N:132Nucleon pairing (Z - N):even - evenNuclear ratio (N/Z ratio):1.5348837209302 (= neutron-proton ratio)Neutron excess (N-Z):46Isotopic mass:218.0056011(25) u (atomic weight of Radon-218)Nuclide mass:217.9584289 u (calculated nuclear mass without electrons)Mass excess:5.21739 MeVMass defect:1.811120564 u (per nucleus)Nuclear binding energy:1687.04793864 MeV (per nucleus)
7.73875201 MeV (average binding energy per nucleon)Separation energy:S_N = 6.512(4) MeV (first neutron)
S_P = 6.466(5) MeV (first proton)Half-life:35(5) msDecay constant λ:19.804205158856 s^-1Specific activity α:5.470812526867 × 10⁺²² Bq g^-1
1478597980234.5 Ci g^-1Spin and parity:
(nuclear angular momentum)0+Charge radius:5.6540(187) femtometer fmYear of discovery:1948

Radioactive Decay

Half-life T_½ = 35(5) ms respectively 3.5 × 10^-2 seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
α	²¹⁴Po	100 %	7.2625(18) MeV

Parent Nuclides

Direct parent isotopes are: ²²²Ra, ²¹⁸At.

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 132) and isobaric (same nucleon number A = 218) with Radon-218. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 132	Isobar A = 218
80	²¹²Hg
81	²¹³Tl
82	²¹⁴Pb	²¹⁸Pb
83	²¹⁵Bi	²¹⁸Bi
84	²¹⁶Po	²¹⁸Po
85	²¹⁷At	²¹⁸At
86	²¹⁸Rn	²¹⁸Rn
87	²¹⁹Fr	²¹⁸Fr
88	²²⁰Ra	²¹⁸Ra
89	²²¹Ac	²¹⁸Ac
90	²²²Th	²¹⁸Th
91	²²³Pa	²¹⁸Pa
92	²²⁴U	²¹⁸U
93	²²⁵Np