Isotopes of gold

Gold (79Au) has one stable isotope, 197Au, and 37 radioisotopes, with 195Au being the most stable with a half-life of 186 days. Gold is currently considered the heaviest monoisotopic element. Bismuth formerly held that distinction until alpha-decay of the 209Bi isotope was observed. All isotopes of gold are either radioactive or, in the case of 197Au, observationally stable, meaning that 197Au is predicted to be radioactive but no actual decay has been observed.[4]

Isotopes of gold (79Au)
Main isotopes[1] Decay
abun­dance half-life (t1/2) mode pro­duct
195Au synth 186.01 d ε 195Pt
196Au synth 6.165 d β+ 196Pt
β− 196Hg
197Au 100% stable
198Au synth 2.69464 d β− 198Hg
199Au synth 3.139 d β− 199Hg
Standard atomic weight Ar°(Au)

List of isotopes
Nuclide
[n 1]		 Z N Isotopic mass (Da)[5]
[n 2][n 3]		 Half-life
[n 4]		 Decay
mode
[n 5]		 Daughter
isotope
[n 6][n 7]		 Spin and
parity
[n 8][n 4]		 Natural abundance (mole fraction)
Excitation energy[n 4] Normal proportion Range of variation
169Au[6] 79 90 168.99808(32)# 1.16+0.50
−0.47 μs		 p (~94%) 168Pt (11/2−)
α (~6%) 165mIr
170Au[7] 79 91 169.99602(22)# 286+50
−40 μs		 p (89%) 169Pt (2−)
α (11%) 166Ir
170mAu[7] 282(10) keV 617+50
−40 μs		 p (58%) 169Pt (9+)
α (42%) 166mIr
171Au 79 92 170.991882(22) 22+3
−2 μs[7]		 p (100%) 170Pt (1/2+)
α (rare) 167Ir
171mAu 258(13) keV 1.014(19) ms α (66%) 167mIr 11/2−
p (34%) 170Pt
172Au 79 93 171.99000(6) 4.7(11) ms α (98%) 168Ir high
p (2%) 171Pt
173Au 79 94 172.986224(24) 25(1) ms α 169Ir (1/2+)
β+ (rare) 173Pt
173mAu 214(23) keV 14.0(9) ms α (96%) 169Ir (11/2−)
β+ (4%) 173Pt
174Au 79 95 173.98491(11)# 139(3) ms α 170Ir low
β+ (rare) 174Pt
174mAu 360(70)# keV 171(29) ms high
175Au 79 96 174.98132(4) 100# ms α (82%) 171Ir 1/2+#
β+ (18%) 175Pt
175mAu 200(30)# keV 156(3) ms α 171Ir 11/2−#
β+ 175Pt
176Au 79 97 175.98012(4) 1.08(17) s
[0.84(+17−14) s]		 α (60%) 172Ir (5−)
β+ (40%) 176Pt
176mAu 150(100)# keV 860(160) ms (7+)
177Au 79 98 176.976870(11) 1.462(32) s β+ (60%) 177Pt (1/2+, 3/2+)
α (40%) 173Ir
177mAu 216(26) keV 1.180(12) s 11/2−
178Au 79 99 177.976057(11) 2.6(5) s β+ (60%) 178Pt
α (40%) 174Ir
179Au 79 100 178.973174(13) 7.1(3) s β+ (78%) 179Pt 5/2−#
α (22%) 175Ir
179mAu 99(16) keV (11/2−)
180Au 79 101 179.972490(5) 8.1(3) s β+ (98.2%) 180Pt
α (1.8%) 176Ir
181Au 79 102 180.970079(21) 13.7(14) s β+ (97.3%) 181Pt (3/2−)
α (2.7%) 177Ir
182Au 79 103 181.969614(20) 15.5(4) s β+ (99.87%) 182Pt (2+)
α (.13%) 178Ir
183Au 79 104 182.967588(10) 42.8(10) s β+ (99.2%) 183Pt (5/2)−
α (.8%) 179Ir
183m1Au 73.3(4) keV >1 μs (1/2)+
183m2Au 230.6(6) keV <1 μs (11/2)−
184Au 79 105 183.967452(24) 20.6(9) s β+ 184Pt 5+
184mAu 68.46(1) keV 47.6(14) s β+ (70%) 184Pt 2+
IT (30%) 184Au
α (.013%) 180Ir
185Au 79 106 184.9657989(28) 4.25(6) min β+ (99.74%) 185Pt 5/2−
α (.26%) 181Ir
185mAu 100(100)# keV 6.8(3) min 1/2+#
186Au 79 107 185.965953(23) 10.7(5) min β+ (99.9992%) 186Pt 3−
α (8×10−4%) 182Ir
186mAu 227.77(7) keV 110(10) ns 2+
187Au 79 108 186.964542(24) 8.4(3) min β+ (99.997%) 187Pt 1/2+
α (.003%) 183Ir
187mAu 120.51(16) keV 2.3(1) s IT 187Au 9/2−
188Au 79 109 187.9652480(29) 8.84(6) min β+ 188Pt 1(−)
189Au 79 110 188.963948(22) 28.7(3) min β+ (99.9997%) 189Pt 1/2+
α (3×10−4%) 185Ir
189m1Au 247.23(16) keV 4.59(11) min β+ 189Pt 11/2−
IT (rare) 189Au
189m2Au 325.11(16) keV 190(15) ns 9/2−
189m3Au 2554.7(12) keV 242(10) ns 31/2+
190Au 79 111 189.964752(4) 42.8(10) min β+ 190Pt 1−
α (<10−6%) 186Ir
190mAu 200(150)# keV 125(20) ms IT 190Au 11−#
β+ (rare) 190Pt
191Au 79 112 190.963716(5) 3.18(8) h β+ 191Pt 3/2+
191m1Au 266.2(5) keV 920(110) ms IT 191Au (11/2−)
191m2Au 2490(1) keV >400 ns
192Au 79 113 191.964818(17) 4.94(9) h β+ 192Pt 1−
192m1Au 135.41(25) keV 29 ms IT 192Au (5#)+
192m2Au 431.6(5) keV 160(20) ms (11−)
193Au 79 114 192.964138(9) 17.65(15) h β+[n 9] 193Pt 3/2+
193m1Au 290.19(3) keV 3.9(3) s IT (99.97%) 193Au 11/2−
β+ (.03%) 193Pt
193m2Au 2486.5(6) keV 150(50) ns (31/2+)
194Au 79 115 193.9654191(23) 38.02(10) h β+ 194Pt 1−
194m1Au 107.4(5) keV 600(8) ms IT 194Au (5+)
194m2Au 475.8(6) keV 420(10) ms (11−)
195Au 79 116 194.9650378(12) 186.098(47) d EC 195Pt 3/2+
195mAu 318.58(4) keV 30.5(2) s IT 195Au 11/2−
196Au 79 117 195.966571(3) 6.1669(6) d β+ (93.05%) 196Pt 2−
β− (6.95%) 196Hg
196m1Au 84.660(20) keV 8.1(2) s IT 196Au 5+
196m2Au 595.66(4) keV 9.6(1) h 12−
197Au[n 10] 79 118 196.9665701(6) Observationally Stable[n 11] 3/2+ 1.0000
197mAu 409.15(8) keV 7.73(6) s IT 197Au 11/2−
198Au 79 119 197.9682437(6) 2.69517(21) d β− 198Hg 2−
198m1Au 312.2200(20) keV 124(4) ns 5+
198m2Au 811.7(15) keV 2.27(2) d IT 198Au (12−)
199Au 79 120 198.9687666(6) 3.139(7) d β− 199Hg 3/2+
199mAu 548.9368(21) keV 440(30) μs (11/2)−
200Au 79 121 199.970757(29) 48.4(3) min β− 200Hg 1(−)
200mAu 970(70) keV 18.7(5) h β− (82%) 200Hg 12−
IT (18%) 200Au
201Au 79 122 200.971658(3) 26(1) min β− 201Hg 3/2+
201m1Au 594(5) keV 730(630) μs (11/2-)
201m2Au 1610(5) keV 5.6(2.4) μs (11/2-)
202Au 79 123 201.973856(25) 28.8(19) s β− 202Hg (1−)
203Au 79 124 202.975154(3) 60(6) s β− 203Hg 3/2+
203mAu 641(3) keV 140(44) μs IT 203Au 11/2−#
204Au 79 125 203.97811(22)# 38.3(1.3) s β− 204Hg (2−)
204mAu 3816(1000)# keV 2.1(0.3) μs IT 204Au 16+#
205Au 79 126 204.98006(22)# 32.5(1.4) s β− 205Hg 3/2+#
205m1Au 907(5) keV 6(2) s 11/2−#
205m2Au 2850(5) keV 163(5) ns 19/2+#
206Au 79 127 205.98477(32)# 47(11) s β− 206Hg (5+, 6+)
207Au 79 128 206.98858(32)# 3# s 3/2+#
208Au 79 129 207.99366(32)# 20# s 6+#
209Au 79 130 208.99761(43)# 1# s 3/2+#
210Au 79 131 210.00288(43)# 10# s 6+#
This table header & footer:
  1. mAu – Excited nuclear isomer.
  2. ( ) – Uncertainty (1σ) is given in concise form in parentheses after the corresponding last digits.
  3. # – Atomic mass marked #: value and uncertainty derived not from purely experimental data, but at least partly from trends from the Mass Surface (TMS).
  4. # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
  5. Modes of decay:
    EC:Electron capture
    IT:Isomeric transition
    p:Proton emission
  6. Bold italics symbol as daughter – Daughter product is nearly stable.
  7. Bold symbol as daughter – Daughter product is stable.
  8. ( ) spin value – Indicates spin with weak assignment arguments.
  9. Theoretically capable of α decay to 189Ir[1]
  10. Potential material for salted bombs
  11. Theoretically predicted to undergo α decay to 193Ir

References
  1. Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S.; Audi, G. (2021). "The NUBASE2020 evaluation of nuclear properties" (PDF). Chinese Physics C. 45 (3): 030001. doi:10.1088/1674-1137/abddae.
  2. "Standard Atomic Weights: Gold". CIAAW. 2017.
  3. Prohaska, Thomas; Irrgeher, Johanna; Benefield, Jacqueline; Böhlke, John K.; Chesson, Lesley A.; Coplen, Tyler B.; Ding, Tiping; Dunn, Philip J. H.; Gröning, Manfred; Holden, Norman E.; Meijer, Harro A. J. (2022-05-04). "Standard atomic weights of the elements 2021 (IUPAC Technical Report)". Pure and Applied Chemistry. doi:10.1515/pac-2019-0603. ISSN 1365-3075.
  4. Belli, P.; Bernabei, R.; Danevich, F. A.; et al. (2019). "Experimental searches for rare alpha and beta decays". European Physical Journal A. 55 (8): 140–1–140–7. arXiv:1908.11458. Bibcode:2019EPJA...55..140B. doi:10.1140/epja/i2019-12823-2. ISSN 1434-601X. S2CID 201664098.
  5. Wang, Meng; Huang, W.J.; Kondev, F.G.; Audi, G.; Naimi, S. (2021). "The AME 2020 atomic mass evaluation (II). Tables, graphs and references*". Chinese Physics C. 45 (3): 030003. doi:10.1088/1674-1137/abddaf.
  6. Hilton, Joshua Ben. "Decays of new nuclides 169Au, 170Hg, 165Pt and the ground state of 165Ir discovered using MARA" (PDF). University of Liverpool. Retrieved 11 June 2023.
  7. Kettunen, H.; Enqvist, T.; Grahn, T.; Greenlees, P. T.; Jones, P.; Julin, R.; Juutinen, S.; Keenan, A.; Kuusiniemi, P.; Leino, M.; Leppänen, A.-P.; Nieminen, P.; Pakarinen, J.; Rahkila, P.; Uusitalo, J. (28 May 2004). "Decay studies of Au 170 , 171 , Hg 171 – 173 , and Tl 176". Physical Review C. 69 (5): 054323. doi:10.1103/PhysRevC.69.054323. ISSN 0556-2813. Retrieved 11 June 2023.
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