Gold-185

Properties and data of the isotope ¹⁸⁵Au.

Content

General data

Name of the isotope:Gold-185; Au-185Symbol:¹⁸⁵Au or 18579AuMass number A:185 (= number of nucleons)Atomic number Z:79 (= number of protons)Neutrons N:106Isotopic mass:184.9657989(28) u (atomic weight of Gold-185)Nuclide mass:184.9224658 u (calculated nuclear mass without electrons)Mass excess:-31.85812 MeVMass defect:1.570859724 u (per nucleus)Nuclear binding energy:1463.24640775 MeV (per nucleus)
7.90944004 MeV (average binding energy per nucleon)Separation energy:S_N = 9.611(22) MeV (first neutron)
S_P = 1.813(16) MeV (first proton)Half-life:4.25(6) minDecay constant λ:0.00271822423749 s^-1Specific activity α:8.89648328644 × 10⁺¹⁸ Bq g^-1
240445494.22824 Ci g^-1Spin and parity:
(nuclear angular momentum)5/2-Magnetic dipole moment:μ(μ_N) = + 2.170(17)Nuclear g-factor:g_l = 0.868Charge radius:5.4296(41) femtometer fmYear of discovery:1960

Radioactive Decay

Half-life T_½ = 4.25(6) min (minutes) respectively 2.55 × 10² seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
α	¹⁸¹Ir	0.26(6) %	5.180(5) MeV
EE/β⁺	¹⁸⁵Pt	99.74(6) %	4.830(26) MeV

Parent Nuclides

Direct parent isotope is: ¹⁸⁵Hg.

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
^185mAu	+x keV	6.8(3) min	5/2-

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 106) and isobaric (same nucleon number A = 185) with Gold-185. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

OZ	Isotone N = 106	Isobar A = 185
64	¹⁷⁰Gd
65	¹⁷¹Tb
66	¹⁷²Dy
67	¹⁷³Ho
68	¹⁷⁴Er
69	¹⁷⁵Tm
70	¹⁷⁶Yb	¹⁸⁵Yb
71	¹⁷⁷Lu	¹⁸⁵Lu
72	¹⁷⁸Hf	¹⁸⁵Hf
73	¹⁷⁹Ta	¹⁸⁵Ta
74	¹⁸⁰W	¹⁸⁵W
75	¹⁸¹Re	¹⁸⁵Re
76	¹⁸²Os	¹⁸⁵Os
77	¹⁸³Ir	¹⁸⁵Ir
78	¹⁸⁴Pt	¹⁸⁵Pt
79	¹⁸⁵Au	¹⁸⁵Au
80	¹⁸⁶Hg	¹⁸⁵Hg
81	¹⁸⁷Tl	¹⁸⁵Tl
82	¹⁸⁸Pb	¹⁸⁵Pb
83	¹⁸⁹Bi	¹⁸⁵Bi
84	¹⁹⁰Po
85	¹⁹¹At