Radon-212

Properties and data of the isotope ²¹²Rn.

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-212; Rn-212Symbol:²¹²Rn or 21286RnMass number A:212 (= number of nucleons)Atomic number Z:86 (= number of protons)Neutrons N:126Nucleon pairing (Z - N):even - evenNuclear ratio (N/Z ratio):1.4651162790698 (= neutron-proton ratio)Neutron excess (N-Z):40Isotopic mass:211.990704(4) u (atomic weight of Radon-212)Nuclide mass:211.9435318 u (calculated nuclear mass without electrons)Mass excess:-8.65917 MeVMass defect:1.774028168 u (per nucleus)Nuclear binding energy:1652.49659432 MeV (per nucleus)
7.79479526 MeV (average binding energy per nucleon)Separation energy:S_N = 7.976(7) MeV (first neutron)
S_P = 4.301(4) MeV (first proton)Half-life:23.9(12) msDecay constant λ:29.001974082006 s^-1Specific activity α:8.277439485216 × 10⁺²² Bq g^-1
2237145806815.4 Ci g^-1Spin and parity:
(nuclear angular momentum)0+Charge radius:5.5915(176) femtometer fmYear of discovery:1950

Radioactive Decay

Half-life T_½ = 23.9(12) ms respectively 2.39 × 10^-2 seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
α	²⁰⁸Po	100 %	6.3851(26) MeV

Parent Nuclides

Direct parent isotopes are: ²¹⁶Ra, ²¹²Fr.

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
^212m1Rn	1639.68(15) keV	118(14) ns	6+

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 126) and isobaric (same nucleon number A = 212) with Radon-212. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 126	Isobar A = 212
76	²⁰²Os
77	²⁰³Ir
78	²⁰⁴Pt
79	²⁰⁵Au
80	²⁰⁶Hg	²¹²Hg
81	²⁰⁷Tl	²¹²Tl
82	²⁰⁸Pb	²¹²Pb
83	²⁰⁹Bi	²¹²Bi
84	²¹⁰Po	²¹²Po
85	²¹¹At	²¹²At
86	²¹²Rn	²¹²Rn
87	²¹³Fr	²¹²Fr
88	²¹⁴Ra	²¹²Ra
89	²¹⁵Ac	²¹²Ac
90	²¹⁶Th	²¹²Th
91	²¹⁷Pa	²¹²Pa
92	²¹⁸U
93	²¹⁹Np