Isotopes of mercury

There are seven stable isotopes of mercury (80Hg) with 202Hg being the most abundant (29.86%). The longest-lived radioisotopes are 194Hg with a half-life of 444 years, and 203Hg with a half-life of 46.612 days. Most of the remaining 40 radioisotopes have half-lives that are less than a day. 199Hg and 201Hg are the most often studied NMR-active nuclei, having spin quantum numbers of 1/2 and 3/2 respectively. All isotopes of mercury are either radioactive or observationally stable, meaning that they are predicted to be radioactive but no actual decay has been observed. These isotopes are predicted to undergo either alpha decay or double beta decay.

Isotopes of mercury (80Hg)
Main isotopes[1] Decay
abun­dance half-life (t1/2) mode pro­duct
194Hg synth 444 y ε 194Au
195Hg synth 9.9 h ε 195Au
196Hg 0.15% stable
197Hg synth 64.14 h ε 197Au
198Hg 10.0% stable
199Hg 16.9% stable
200Hg 23.1% stable
201Hg 13.2% stable
202Hg 29.7% stable
203Hg synth 46.612 d β 203Tl
204Hg 6.82% stable
Standard atomic weight Ar°(Hg)
  • 200.592±0.003
  • 200.59±0.01 (abridged)[2][3]

180Hg, producible from 180Tl, was found in 2010 to be capable of an unusual form of spontaneous fission.[4] The fission products are 80Kr and 100Ru.

List of isotopes


Nuclide
[n 1]
Z N Isotopic mass (Da)
[n 2][n 3]
Half-life
[n 4]
Decay
mode

[n 5]
Daughter
isotope

[n 6]
Spin and
parity
[n 7][n 4]
Natural abundance (mole fraction)
Excitation energy[n 4] Normal proportion Range of variation
170Hg[5] 80 90 80(+400-40) μs α 166Pt 0+
171Hg 80 91 171.00376(32)# 80(30) μs
[59(+36−16) μs]
α 167Pt 3/2−#
172Hg 80 92 171.99883(22) 420(240) μs
[0.25(+35−9) ms]
α 168Pt 0+
173Hg 80 93 172.99724(22)# 1.1(4) ms
[0.6(+5−2) ms]
α 169Pt 3/2−#
174Hg 80 94 173.992864(21) 2.0(4) ms
[2.1(+18−7) ms]
α 170Pt 0+
175Hg 80 95 174.99142(11) 10.8(4) ms α 171Pt 5/2−#
176Hg 80 96 175.987355(15) 20.4(15) ms α (98.6%) 172Pt 0+
β+ (1.4%) 176Au
177Hg 80 97 176.98628(8) 127.3(18) ms α (85%) 173Pt 5/2−#
β+ (15%) 177Au
178Hg 80 98 177.982483(14) 0.269(3) s α (70%) 174Pt 0+
β+ (30%) 178Au
179Hg 80 99 178.981834(29) 1.09(4) s α (53%) 175Pt 5/2−#
β+ (47%) 179Au
β+, p (.15%) 178Pt
180Hg[n 8] 80 100 179.978266(15) 2.58(1) s β+ (52%) 180Au 0+
α (48%) 176Pt
SF 100Ru, 80Kr
181Hg 80 101 180.977819(17) 3.6(1) s β+ (64%) 181Au 1/2(−)
α (36%) 177Pt
β+, p (.014%) 180Pt
β+, α (9×10−6%) 177Ir
181mHg 210(40)# keV 13/2+
182Hg 80 102 181.97469(1) 10.83(6) s β+ (84.8%) 182Au 0+
α (15.2%) 178Pt
β+, p (10−5%) 181Pt
183Hg 80 103 182.974450(9) 9.4(7) s β+ (74.5%) 183Au 1/2−
α (25.5%) 179Pt
β+, p (5.6×10−4%) 182Pt
183m1Hg 198(14) keV 13/2+#
183m2Hg 240(40)# keV 5# s β+ 183Au 13/2+#
184Hg 80 104 183.971713(11) 30.6(3) s β+ (98.89%) 184Au 0+
α (1.11%) 180Pt
185Hg 80 105 184.971899(17) 49.1(10) s β+ (94%) 185Au 1/2−
α (6%) 181Pt
185mHg 99.3(5) keV 21.6(15) s IT (54%) 185Hg 13/2+
β+ (46%) 185Au
α (.03%) 181Pt
186Hg 80 106 185.969362(12) 1.38(6) min β+ (99.92%) 186Au 0+
α (.016%) 182Pt
186mHg 2217.3(4) keV 82(5) μs (8−)
187Hg 80 107 186.969814(15) 1.9(3) min β+ 187Au 3/2−
α (1.2×10−4%) 183Pt
187mHg 59(16) keV 2.4(3) min β+ 187Au 13/2+
α (2.5×10−4%) 183Pt
188Hg 80 108 187.967577(12) 3.25(15) min β+ 188Au 0+
α (3.7×10−5%) 184Pt
188mHg 2724.3(4) keV 134(15) ns (12+)
189Hg 80 109 188.96819(4) 7.6(1) min β+ 189Au 3/2−
α (3×10−5%) 185Pt
189mHg 80(30) keV 8.6(1) min β+ 189Au 13/2+
α (3×10−5%) 185Pt
190Hg 80 110 189.966322(17) 20.0(5) min β+ 190Au 0+
α (5×10−5%) 186Pt
191Hg 80 111 190.967157(24) 49(10) min β+ 191Au 3/2(−)
191mHg 128(22) keV 50.8(15) min β+ 191Au 13/2+
192Hg 80 112 191.965634(17) 4.85(20) h EC 192Au 0+
α (4×10−6%) 188Pt
193Hg 80 113 192.966665(17) 3.80(15) h β+ 193Au 3/2−
193mHg 140.76(5) keV 11.8(2) h β+ (92.9%) 193Au 13/2+
IT (7.1%) 193Hg
194Hg 80 114 193.965439(13) 444(77) y EC 194Au 0+
195Hg 80 115 194.966720(25) 10.53(3) h β+ 195Au 1/2−
195mHg 176.07(4) keV 41.6(8) h IT (54.2%) 195Hg 13/2+
β+ (45.8%) 195Au
196Hg 80 116 195.965833(3) Observationally Stable[n 9] 0+ 0.0015(1)
197Hg 80 117 196.967213(3) 64.14(5) h EC 197Au 1/2−
197mHg 298.93(8) keV 23.8(1) h IT (91.4%) 197Hg 13/2+
EC (8.6%) 197Au
198Hg 80 118 197.9667690(4) Observationally Stable[n 10] 0+ 0.0997(20)
199Hg 80 119 198.9682799(4) Observationally Stable[n 11] 1/2− 0.1687(22)
199mHg 532.48(10) keV 42.66(8) min IT 199Hg 13/2+
200Hg 80 120 199.9683260(4) Observationally Stable[n 12] 0+ 0.2310(19)
201Hg 80 121 200.9703023(6) Observationally Stable[n 13] 3/2− 0.1318(9)
201mHg 766.22(15) keV 94(3) μs 13/2+
202Hg 80 122 201.9706430(6) Observationally Stable[n 14] 0+ 0.2986(26)
203Hg 80 123 202.9728725(18) 46.595(6) d β 203Tl 5/2−
203mHg 933.14(23) keV 24(4) μs (13/2+)
204Hg 80 124 203.9734939(4) Observationally Stable[n 15] 0+ 0.0687(15)
205Hg 80 125 204.976073(4) 5.14(9) min β 205Tl 1/2−
205mHg 1556.40(17) keV 1.09(4) ms IT 205Hg 13/2+
206Hg 80 126 205.977514(22) 8.15(10) min β 206Tl 0+ Trace[n 16]
207Hg 80 127 206.98259(16) 2.9(2) min β 207Tl (9/2+)
208Hg 80 128 207.98594(32)# 42(5) min
[41(+5−4) min]
β 208Tl 0+
209Hg 80 129 208.99104(21)# 37(8) s 9/2+#
210Hg 80 130 209.99451(32)# 10# min
[>300 ns]
0+
211Hg 80 131 210.99380(200)# 26(8) s 9/2+#
212Hg 80 132 212.02760(300)# 1# min
[>300 ns]
0+
213Hg 80 133 213.07670(300)# 1# s
[>300 ns]
5/2+#
214Hg 80 134 214.11180(400)# 1# s
[>300 ns]
0+
215Hg 80 135 215.16210(400)# 1# s
[>300 ns]
3/2+#
216Hg 80 136 216.19860(400)# 100# ms
[>300 ns]
0+
This table header & footer:
  1. mHg  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
    SF:Spontaneous fission
  6. Bold symbol as daughter  Daughter product is stable.
  7. () spin value  Indicates spin with weak assignment arguments.
  8. When produced from 180Tl can also undergo fission to 100Ru and 80Kr
  9. Believed to undergo β+β+ decay to 196Pt with a half-life over 2.5×1018 years
  10. Believed to undergo α decay to 194Pt
  11. Believed to undergo α decay to 195Pt
  12. Believed to undergo α decay to 196Pt
  13. Believed to undergo α decay to 197Pt
  14. Believed to undergo α decay to 198Pt
  15. Believed to undergo ββ decay to 204Pb
  16. Intermediate decay product of 238U

Particular Isotopes

Hg-196

While it is the rarest stable isotope of Mercury, at a proportion lower than that of 235
U
in natural uranium, Hg-196 is of some theoretical interest in the synthesis of precious metals via nuclear transmutation since it could - in theory - be transmutated into the only stable gold isotope 197
Au
via neutron absorption and subsequent decay via electron capture. However, given that a costly step of isotope separation would have to precede the already costly process of transmutation, this has (as of 2022) mostly remained a theoretical curiosity rather than an actual area of research.

Hg-198

At roughly 10% of natural Mercury, Hg-198 is neither particularly abundant nor particularly rare. It has a non-negligible gamma ray cross section for the (γ, n) reaction with 10 Mega-Electronvolt Gamma Rays. This reaction, in addition to serving as a potential neutron source could also be used to produce Hg-197 and via electron capture produce 197
Au
- stable gold. Given that it is roughly two orders of magnitude more abundant that Hg-196, the required isotopic separation, even it required a further step of separating the lighter Hg-196 from the heavier Hg-198 could be achieved with a better yield for any given effort than for Hg-196.

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: Mercury". CIAAW. 2011.
  3. Prohaska, Thomas; Irrgeher, Johanna; Benefield, Jacqueline; et al. (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. Eugenie Samuel Reich (December 1, 2010). "Mercury serves up a nuclear surprise: a new type of fission". Scientific American.
  5. Hilton, J.; et al. (2019). "α-spectroscopy studies of the new nuclides 165Pt and 170Hg". Physical Review C. 100 (1): 014305. Bibcode:2019PhRvC.100a4305H. doi:10.1103/PhysRevC.100.014305. S2CID 199118719.
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