Mercury-205

Properties and data of the isotope ²⁰⁵Hg.

Contents

General Data

Radioactive Decay

Parent Nuclides

Isotones und Isobares

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

General data

Name of the isotope:Mercury-205; Hg-205Symbol:²⁰⁵Hg or 20580HgMass number A:205 (= number of nucleons)Atomic number Z:80 (= number of protons)Neutrons N:125Isotopic mass:204.976073(4) u (atomic weight of Mercury-205)Nuclide mass:204.9321914 u (calculated nuclear mass without electrons)Mass excess:-22.28786 MeVMass defect:1.73304406 u (per nucleus)Nuclear binding energy:1614.32014363 MeV (per nucleus)
7.87473241 MeV (average binding energy per nucleon)Separation energy:S_N = 5.669(4) MeV (first neutron)
S_P = 8.93(20) MeV (first proton)Half-life:5.14(9) minDecay constant λ:0.002247558951232 s^-1Specific activity α:6.634861076142 × 10⁺¹⁸ Bq g^-1
179320569.62547 Ci g^-1Spin and parity:
(nuclear angular momentum)1/2-Charge radius:5.4776(38) femtometer fmYear of discovery:1940

Radioactive Decay

Half-life T_½ = 5.14(9) min (minutes) respectively 3.084 × 10² seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
β^-	²⁰⁵Tl	100 %	1.533(4) MeV

Parent Nuclides

Direct parent isotope is: ²⁰⁵Au.

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
^205mHg	1556.40(17) keV	1.09(4) ms	13/2+

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 125) and isobaric (same nucleon number A = 205) with Mercury-205. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 125	Isobar A = 205
76	²⁰¹Os
77	²⁰²Ir	²⁰⁵Ir
78	²⁰³Pt	²⁰⁵Pt
79	²⁰⁴Au	²⁰⁵Au
80	²⁰⁵Hg	²⁰⁵Hg
81	²⁰⁶Tl	²⁰⁵Tl
82	²⁰⁷Pb	²⁰⁵Pb
83	²⁰⁸Bi	²⁰⁵Bi
84	²⁰⁹Po	²⁰⁵Po
85	²¹⁰At	²⁰⁵At
86	²¹¹Rn	²⁰⁵Rn
87	²¹²Fr	²⁰⁵Fr
88	²¹³Ra	²⁰⁵Ra
89	²¹⁴Ac	²⁰⁵Ac
90	²¹⁵Th
91	²¹⁶Pa
92	²¹⁷U