Radon-199m

Properties and data of the isotope ^199mRn.

Contents

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

General data

Name of the isotope:Radon-199m; Rn-199mSymbol:^199mRn or 199m86RnMass number A:199 (= number of nucleons)Atomic number Z:86 (= number of protons)Neutrons N:113Nucleon pairing (Z - N):even - oddNuclear ratio (N/Z ratio):1.3139534883721 (= neutron-proton ratio)Neutron excess (N-Z):27Excitation energy:180(70) keVIsotopic mass:198.99839(4) u (atomic weight of Radon-199m)Nuclide mass:198.9512178 u (calculated nuclear mass without electrons)Mass excess:-1.49971 MeVMass defect:1.65369826 u (per nucleus)Nuclear binding energy:1540.410007 MeV (per nucleus)
7.7407538 MeV (average binding energy per nucleon)Half-life:0.31(2) sDecay constant λ:2.2359586469676 s^-1Specific activity α:6.800635317693 × 10⁺²¹ Bq g^-1
183800954532.25 Ci g^-1Spin and parity:
(nuclear angular momentum)(13/2+)

Radioactive Decay

Half-life T_½ = 0.31(2) s respectively 3.1 × 10^-1 seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
α	¹⁹⁵Po	97 %
EC/β⁺	¹⁹⁹At	3 %

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
¹⁹⁹Rn		0.59(3) s	(3/2-)

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 113) and isobaric (same nucleon number A = 199) with Radon-199m. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 113	Isobar A = 199
70	¹⁸³Yb
71	¹⁸⁴Lu
72	¹⁸⁵Hf
73	¹⁸⁶Ta
74	¹⁸⁷W
75	¹⁸⁸Re	¹⁹⁹Re
76	¹⁸⁹Os	¹⁹⁹Os
77	¹⁹⁰Ir	¹⁹⁹Ir
78	¹⁹¹Pt	¹⁹⁹Pt
79	¹⁹²Au	¹⁹⁹Au
80	¹⁹³Hg	¹⁹⁹Hg
81	¹⁹⁴Tl	¹⁹⁹Tl
82	¹⁹⁵Pb	¹⁹⁹Pb
83	¹⁹⁶Bi	¹⁹⁹Bi
84	¹⁹⁷Po	¹⁹⁹Po
85	¹⁹⁸At	¹⁹⁹At
86	¹⁹⁹Rn	¹⁹⁹Rn
87	²⁰⁰Fr	¹⁹⁹Fr
88	²⁰¹Ra