Radon-209m1

Properties and data of the isotope ²⁰⁹Rn.

Content

General data

Name of the isotope:Radon-209m1; Rn-209m1Symbol:²⁰⁹Rn or 20986RnMass number A:209 (= number of nucleons)Atomic number Z:86 (= number of protons)Neutrons N:123Isotopic mass:208.990401(11) u (atomic weight of Radon-209m1)
Excitation energy: 1174.01(13) keVNuclide mass:208.9432288 u (calculated nuclear mass without electrons)Mass excess:-8.94141 MeVMass defect:1.74833642 u (per nucleus)Nuclear binding energy:1628.56488521 MeV (per nucleus)
7.79217648 MeV (average binding energy per nucleon)Half-life:13.4(13) μsDecay constant λ:51727.401534324 s^-1Specific activity α:1.497642780568 × 10⁺²⁶ Bq g^-1
4.047683190725 × 10⁺¹⁵ Ci g^-1Spin and parity:
(nuclear angular momentum)13/2+

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
²⁰⁹Rn		28.8(10) min	5/2-
^209m2Rn	3636.81(23) keV	3.0(3) μs	35/2+

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 123) and isobaric (same nucleon number A = 209) with Radon-209m1. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

OZ	Isotone N = 123	Isobar A = 209
74	¹⁹⁷W
75	¹⁹⁸Re
76	¹⁹⁹Os
77	²⁰⁰Ir
78	²⁰¹Pt
79	²⁰²Au	²⁰⁹Au
80	²⁰³Hg	²⁰⁹Hg
81	²⁰⁴Tl	²⁰⁹Tl
82	²⁰⁵Pb	²⁰⁹Pb
83	²⁰⁶Bi	²⁰⁹Bi
84	²⁰⁷Po	²⁰⁹Po
85	²⁰⁸At	²⁰⁹At
86	²⁰⁹Rn	²⁰⁹Rn
87	²¹⁰Fr	²⁰⁹Fr
88	²¹¹Ra	²⁰⁹Ra
89	²¹²Ac	²⁰⁹Ac
90	²¹³Th	²⁰⁹Th
91	²¹⁴Pa
92	²¹⁵U