Gold-208

Properties and data of the isotope ²⁰⁸Au.

Content

General data

Name of the isotope:Gold-208; Au-208Symbol:²⁰⁸Au or 20879AuMass number A:208 (= number of nucleons)Atomic number Z:79 (= number of protons)Neutrons N:129Isotopic mass:207.99345(32) u (atomic weight of Gold-208)Nuclide mass:207.9501169 u (calculated nuclear mass without electrons)Mass excess:-6.10129 MeVMass defect:1.742501692 u (per nucleus)Nuclear binding energy:1623.12987109 MeV (per nucleus)
7.803509 MeV (average binding energy per nucleon)Separation energy:S_N = 3.36(42) MeV (first neutron)
S_P = 8.85(50) MeV (first proton)Half-life:300 nsDecay constant λ:2310490.6018665 s^-1Specific activity α:6.721787371980 × 10⁺²⁷ Bq g^-1
1.816699289724 × 10⁺¹⁷ Ci g^-1Spin and parity:
(nuclear angular momentum)Year of discovery:2010

Radioactive Decay

Half-life T_½ = 300 ns respectively 3.0 × 10^-7 seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
β^-	²⁰⁸Hg	?	7.16(30) MeV
β^-, n	²⁰⁷Hg	?	2.31(30) 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 = 208) with Gold-208. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

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