Gold-205

Properties and data of the isotope ²⁰⁵Au.

Content

General data

Name of the isotope:Gold-205; Au-205Symbol:²⁰⁵Au or 20579AuMass number A:205 (= number of nucleons)Atomic number Z:79 (= number of protons)Neutrons N:126Isotopic mass:204.97985(21) u (atomic weight of Gold-205)Nuclide mass:204.9365169 u (calculated nuclear mass without electrons)Mass excess:-18.7696 MeVMass defect:1.730106944 u (per nucleus)Nuclear binding energy:1611.58423769 MeV (per nucleus)
7.86138653 MeV (average binding energy per nucleon)Separation energy:S_N = 6.19(28) MeV (first neutron)
S_P = 8.14(28) MeV (first proton)Half-life:31(2) sDecay constant λ:0.022359586469676 s^-1Specific activity α:6.600616631878 × 10⁺¹⁹ Bq g^-1
1783950441.0483 Ci g^-1Spin and parity:
(nuclear angular momentum)(3/2+)Year of discovery:1994

Radioactive Decay

Half-life T_½ = 31(2) s respectively 3.1 × 10¹ seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
β^-	²⁰⁵Hg	100 %	3.52(20) MeV

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 126) and isobaric (same nucleon number A = 205) with Gold-205. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

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