Gold-199

Properties and data of the isotope ¹⁹⁹Au.

Content

General data

Name of the isotope:Gold-199; Au-199Symbol:¹⁹⁹Au or 19979AuMass number A:199 (= number of nucleons)Atomic number Z:79 (= number of protons)Neutrons N:120Isotopic mass:198.9687666(6) u (atomic weight of Gold-199)Nuclide mass:198.9254335 u (calculated nuclear mass without electrons)Mass excess:-29.09372 MeVMass defect:1.689200848 u (per nucleus)Nuclear binding energy:1573.48045471 MeV (per nucleus)
7.90693696 MeV (average binding energy per nucleon)Separation energy:S_N = 7.58428(6) MeV (first neutron)
S_P = 6.4787(21) MeV (first proton)Half-life:3.139(7) dDecay constant λ:2.555758196821 × 10^-9 s^-1Specific activity α:7773300942018.5 Bq g^-1
210.08921464915 Ci g^-1Spin and parity:
(nuclear angular momentum)3/2+Magnetic dipole moment:μ(μ_N) = + 0.2715(7)Quadrupole moment Q:+ 0.510(16) barn (100 fm²)Nuclear g-factor:g_l = 0.181Charge radius:5.4454(39) femtometer fmYear of discovery:1937

Radioactive Decay

Half-life T_½ = 3.139(7) d respectively 2.7121 × 10⁸ seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
β^-	¹⁹⁹Hg	100 %	0.4523(6) MeV

Parent Nuclides

Direct parent isotope is: ¹⁹⁹Pt.

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
^199mAu	548.9405(21) keV	0.44(3) ms	(11/2)-

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 120) and isobaric (same nucleon number A = 199) with Gold-199. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

OZ	Isotone N = 120	Isobar A = 199
73	¹⁹³Ta
74	¹⁹⁴W
75	¹⁹⁵Re	¹⁹⁹Re
76	¹⁹⁶Os	¹⁹⁹Os
77	¹⁹⁷Ir	¹⁹⁹Ir
78	¹⁹⁸Pt	¹⁹⁹Pt
79	¹⁹⁹Au	¹⁹⁹Au
80	²⁰⁰Hg	¹⁹⁹Hg
81	²⁰¹Tl	¹⁹⁹Tl
82	²⁰²Pb	¹⁹⁹Pb
83	²⁰³Bi	¹⁹⁹Bi
84	²⁰⁴Po	¹⁹⁹Po
85	²⁰⁵At	¹⁹⁹At
86	²⁰⁶Rn	¹⁹⁹Rn
87	²⁰⁷Fr	¹⁹⁹Fr
88	²⁰⁸Ra
89	²⁰⁹Ac
90	²¹⁰Th