Mercury-209

Properties and data of the isotope ²⁰⁹Hg.

Contents

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

General data

Name of the isotope:Mercury-209; Hg-209Symbol:²⁰⁹Hg or 20980HgMass number A:209 (= number of nucleons)Atomic number Z:80 (= number of protons)Neutrons N:129Isotopic mass:208.99072(16) u (atomic weight of Mercury-209)Nuclide mass:208.9468384 u (calculated nuclear mass without electrons)Mass excess:-8.64426 MeVMass defect:1.753056724 u (per nucleus)Nuclear binding energy:1632.96182007 MeV (per nucleus)
7.81321445 MeV (average binding energy per nucleon)Separation energy:S_N = 3.45(15) MeV (first neutron)
S_P = 9.83(33) MeV (first proton)Half-life:36 sDecay constant λ:0.019254088348887 s^-1Specific activity α:5.574559238782 × 10⁺¹⁹ Bq g^-1
1506637632.1033 Ci g^-1Spin and parity:
(nuclear angular momentum)(9/2+)Year of discovery:1998

Radioactive Decay

Half-life T_½ = 36 s respectively 3.6 × 10¹ seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
β^-	²⁰⁹Tl	100 %	5.00(15) MeV

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 129) and isobaric (same nucleon number A = 209) with Mercury-209. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 129	Isobar A = 209
78	²⁰⁷Pt
79	²⁰⁸Au	²⁰⁹Au
80	²⁰⁹Hg	²⁰⁹Hg
81	²¹⁰Tl	²⁰⁹Tl
82	²¹¹Pb	²⁰⁹Pb
83	²¹²Bi	²⁰⁹Bi
84	²¹³Po	²⁰⁹Po
85	²¹⁴At	²⁰⁹At
86	²¹⁵Rn	²⁰⁹Rn
87	²¹⁶Fr	²⁰⁹Fr
88	²¹⁷Ra	²⁰⁹Ra
89	²¹⁸Ac	²⁰⁹Ac
90	²¹⁹Th	²⁰⁹Th
91	²²⁰Pa
92	²²¹U