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Isotopes of lead

(Redirected from Lead-208)

Lead (82Pb) has four observationally stable isotopes: 204Pb, 206Pb, 207Pb, 208Pb. Lead-204 is entirely a primordial nuclide and is not a radiogenic nuclide. The three isotopes lead-206, lead-207, and lead-208 represent the ends of three decay chains: the uranium series (or radium series), the actinium series, and the thorium series, respectively; a fourth decay chain, the neptunium series, terminates with the thallium isotope 205Tl. The three series terminating in lead represent the decay chain products of long-lived primordial 238U, 235U, and 232Th. Each isotope also occurs, to some extent, as primordial isotopes that were made in supernovae, rather than radiogenically as daughter products. The fixed ratio of lead-204 to the primordial amounts of the other lead isotopes may be used as the baseline to estimate the extra amounts of radiogenic lead present in rocks as a result of decay from uranium and thorium. (See lead–lead dating and uranium–lead dating.)

Isotopes of lead (82Pb)
Main isotopes[1] Decay
abun­dance half-life (t1/2) mode pro­duct
202Pb synth 5.25×104 y ε 202Tl
204Pb 1.40% stable
205Pb trace 1.73×107 y ε 205Tl
206Pb 24.1% stable
207Pb 22.1% stable
208Pb 52.4% stable
209Pb trace 3.253 h β− 209Bi
210Pb trace 22.20 y β− 210Bi
211Pb trace 36.1 min β− 211Bi
212Pb trace 10.64 h β− 212Bi
214Pb trace 26.8 min β− 214Bi
Isotopic abundances vary greatly by sample[2]
Standard atomic weight Ar°(Pb)

The longest-lived radioisotopes are 205Pb with a half-life of 17.3 million years and 202Pb with a half-life of 52,500 years. A shorter-lived naturally occurring radioisotope, 210Pb with a half-life of 22.2 years, is useful for studying the sedimentation chronology of environmental samples on time scales shorter than 100 years.[5]

The relative abundances of the four stable isotopes are approximately 1.5%, 24%, 22%, and 52.5%, combining to give a standard atomic weight (abundance-weighted average of the stable isotopes) of 207.2(1). Lead is the element with the heaviest stable isotope, 208Pb. (The more massive 209Bi, long considered to be stable, actually has a half-life of 2.01×1019 years.) 208Pb is also a doubly magic isotope, as it has 82 protons and 126 neutrons.[6] It is the heaviest doubly magic nuclide known. A total of 43 lead isotopes are now known, including very unstable synthetic species.

The four primordial isotopes of lead are all observationally stable, meaning that they are predicted to undergo radioactive decay but no decay has been observed yet. These four isotopes are predicted to undergo alpha decay and become isotopes of mercury which are themselves radioactive or observationally stable.

In its fully ionized state, the beta decay of isotope 210Pb does not release a free electron; the generated electron is instead captured by the atom's empty orbitals.[7]

List of isotopes

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Nuclide
[n 1] 		Historic
name 		Z N Isotopic mass (Da)[8]
[n 2][n 3] 		Half-life[1]
 Decay
mode[1]
[n 4] 		Daughter
isotope
[n 5][n 6] 		Spin and
parity[1]
[n 7][n 8] 		Natural abundance (mole fraction)
Excitation energy[n 8] Normal proportion[1] Range of variation
178Pb 82 96 178.003836(25) 250(80) μs α 174Hg 0+
β+? 178Tl
179Pb 82 97 179.002(87) 2.7(2) ms α 175Hg (9/2−)
180Pb 82 98 179.997916(13) 4.1(3) ms α 176Hg 0+
181Pb 82 99 180.996661(91) 39.0(8) ms α 177Hg (9/2−)
β+? 181Tl
182Pb 82 100 181.992674(13) 55(5) ms α 178Hg 0+
β+? 182Tl
183Pb 82 101 182.991863(31) 535(30) ms α 179Hg 3/2−
β+? 183Tl
183mPb 94(8) keV 415(20) ms α 179Hg 13/2+
β+? 183Tl
IT? 183Pb
184Pb 82 102 183.988136(14) 490(25) ms α (80%) 180Hg 0+
β+? (20%) 184Tl
185Pb 82 103 184.987610(17) 6.3(4) s β+ (66%) 185Tl 3/2−
α (34%) 181Hg
185mPb[n 9] 70(50) keV 4.07(15) s α (50%) 181Hg 13/2+
β+? (50%) 185Tl
186Pb 82 104 185.984239(12) 4.82(3) s β+? (60%) 186Tl 0+
α (40%) 182Hg
187Pb 82 105 186.9839108(55) 15.2(3) s β+ (90.5%) 187Tl 3/2−
α (9.5%) 183Hg
187mPb[n 9] 19(10) keV 18.3(3) s β+ (88%) 187Tl 13/2+
α (12%) 183Hg
188Pb 82 106 187.980879(11) 25.1(1) s β+ (91.5%) 188Tl 0+
α (8.5%) 184Hg
188m1Pb 2577.2(4) keV 800(20) ns IT 188Pb 8−
188m2Pb 2709.8(5) keV 94(12) ns IT 188Pb 12+
188m3Pb 4783.4(7) keV 440(60) ns IT 188Pb (19−)
189Pb 82 107 188.980844(15) 39(8) s β+ (99.58%) 189Tl 3/2−
α (0.42%) 185Hg
189m1Pb 40(4) keV 50.5(21) s β+ (99.6%) 189Tl 13/2+
α (0.4%) 185Hg
IT? 189Pb
189m2Pb 2475(4) keV 26(5) μs IT 189Pb 31/2−
190Pb 82 108 189.978082(13) 71(1) s β+ (99.60%) 190Tl 0+
α (0.40%) 186Hg
190m1Pb 2614.8(8) keV 150(14) ns IT 190Pb 10+
190m2Pb 2665(50)# keV 24.3(21) μs IT 190Pb (12+)
190m3Pb 2658.2(8) keV 7.7(3) μs IT 190Pb 11−
191Pb 82 109 190.9782165(71) 1.33(8) min β+ (99.49%) 191Tl 3/2−
α (0.51%) 187Hg
191m1Pb 58(10) keV 2.18(8) min β+ (99.98%) 191Tl 13/2+
α (0.02%) 187Hg
191m2Pb 2659(10) keV 180(80) ns IT 191Pb 33/2+
192Pb 82 110 191.9757896(61) 3.5(1) min β+ (99.99%) 192Tl 0+
α (0.0059%) 188Hg
192m1Pb 2581.1(1) keV 166(6) ns IT 192Pb 10+
192m2Pb 2625.1(11) keV 1.09(4) μs IT 192Pb 12+
192m3Pb 2743.5(4) keV 756(14) ns IT 192Pb 11−
193Pb 82 111 192.976136(11) 4# min β+? 193Tl 3/2−#
193m1Pb 93(12) keV 5.8(2) min β+ 193Tl 13/2+
193m2Pb 2707(13) keV 180(15) ns IT 193Pb 33/2+
194Pb 82 112 193.974012(19) 10.7(6) min β+ 194Tl 0+
α (7.3×10−6%) 190Hg
194m1Pb 2628.1(4) keV 370(13) ns IT 194Pb 12+
194m2Pb 2933.0(4) keV 133(7) ns IT 194Pb 11−
195Pb 82 113 194.9745162(55) 15.0(14) min β+ 195Tl 3/2-
195m1Pb 202.9(7) keV 15.0(12) min β+ 195Tl 13/2+
IT? 195Pb
195m2Pb 1759.0(7) keV 10.0(7) μs IT 195Pb 21/2−
195m3Pb 2901.7(8) keV 95(20) ns IT 195Pb 33/2+
196Pb 82 114 195.9727876(83) 37(3) min β+ 196Tl 0+
α (<3×10−5%) 192Hg
196m1Pb 1797.51(14) keV 140(14) ns IT 196Pb 5−
196m2Pb 2694.6(3) keV 270(4) ns IT 196Pb 12+
197Pb 82 115 196.9734347(52) 8.1(17) min β+ 197Tl 3/2−
197m1Pb 319.31(11) keV 42.9(9) min β+ (81%) 197Tl 13/2+
IT (19%) 197Pb
197m2Pb 1914.10(25) keV 1.15(20) μs IT 197Pb 21/2−
198Pb 82 116 197.9720155(94) 2.4(1) h β+ 198Tl 0+
198m1Pb 2141.4(4) keV 4.12(7) μs IT 198Pb 7−
198m2Pb 2231.4(5) keV 137(10) ns IT 198Pb 9−
198m3Pb 2821.7(6) keV 212(4) ns IT 198Pb 12+
199Pb 82 117 198.9729126(73) 90(10) min β+ 199Tl 3/2−
199m1Pb 429.5(27) keV 12.2(3) min IT 199Pb (13/2+)
β+? 199Tl
199m2Pb 2563.8(27) keV 10.1(2) μs IT 199Pb (29/2−)
200Pb 82 118 199.971819(11) 21.5(4) h EC 200Tl 0+
200m1Pb 2183.3(11) keV 456(6) ns IT 200Pb (9−)
200m2Pb 3005.8(12) keV 198(3) ns IT 200Pb 12+)
201Pb 82 119 200.972870(15) 9.33(3) h β+ 201Tl 5/2−
201m1Pb 629.1(3) keV 60.8(18) s IT 201Pb 13/2+
β+? 201Tl
201m2Pb 2953(20) keV 508(3) ns IT 201Pb (29/2−)
202Pb 82 120 201.9721516(41) 5.25(28)×104 y EC 202Tl 0+
202m1Pb 2169.85(8) keV 3.54(2) h IT (90.5%) 202Pb 9−
β+ (9.5%) 202Tl
202m2Pb 4140(50)# keV 100(3) ns IT 202Pb 16+
202m3Pb 5300(50)# keV 108(3) ns IT 202Pb 19−
203Pb 82 121 202.9733906(70) 51.924(15) h EC 203Tl 5/2−
203m1Pb 825.2(3) keV 6.21(8) s IT 203Pb 13/2+
203m2Pb 2949.2(4) keV 480(7) ms IT 203Pb 29/2−
203m3Pb 2970(50)# keV 122(4) ns IT 203Pb 25/2−#
204Pb[n 10] 82 122 203.9730435(12) Observationally stable[n 11] 0+ 0.014(6) 0.0000–0.0158[10]
204m1Pb 1274.13(5) keV 265(6) ns IT 204Pb 4+
204m2Pb 2185.88(8) keV 66.93(10) min IT 204Pb 9−
204m3Pb 2264.42(6) keV 490(70) ns IT 204Pb 7−
205Pb 82 123 204.9744817(12) 17.0(9)×107 y EC 205Tl 5/2−
205m1Pb 2.329(7) keV 24.2(4) μs IT 205Pb 1/2−
205m2Pb 1013.85(3) keV 5.55(2) ms IT 205Pb 13/2+
205m3Pb 3195.8(6) keV 217(5) ns IT 205Pb 25/2−
206Pb[n 10][n 12] Radium G[11] 82 124 205.9744652(12) Observationally stable[n 13] 0+ 0.241(30) 0.0190–0.8673[10]
206m1Pb 2200.16(4) keV 125(2) μs IT 206Pb 7−
206m2Pb 4027.3(7) keV 202(3) ns IT 206Pb 12+
207Pb[n 10][n 14] Actinium D 82 125 206.9758968(12) Observationally stable[n 15] 1/2− 0.221(50) 0.0035–0.2351[10]
207mPb 1633.356(4) keV 806(5) ms IT 207Pb 13/2+
208Pb[n 16] Thorium D 82 126 207.9766520(12) Observationally stable[n 17] 0+ 0.524(70) 0.0338–0.9775[10]
208mPb 4895.23(5) keV 535(35) ns IT 208Pb 10+
209Pb 82 127 208.9810900(19) 3.235(5) h β− 209Bi 9/2+ Trace[n 18]
210Pb Radium D
Radiolead
Radio-lead 		82 128 209.9841884(16) 22.20(22) y β− (100%) 210Bi 0+ Trace[n 19]
α (1.9×10−6%) 206Hg
210m1Pb 1194.61(18) keV 92(10) ns IT 210Pb 6+
210m2Pb 1274.8(3) keV 201(17) ns IT 210Pb 8+
211Pb Actinium B 82 129 210.9887353(24) 36.1628(25) min β− 211Bi 9/2+ Trace[n 20]
211mPb 1719(23) keV 159(28) ns IT 211Pb (27/2+)
212Pb Thorium B 82 130 211.9918959(20) 10.627(6) h β− 212Bi 0+ Trace[n 21]
212mPb 1335(2) keV 6.0(8) μs IT 212Pb 8+#
213Pb 82 131 212.9965608(75) 10.2(3) min β− 213Bi (9/2+) Trace[n 18]
213mPb 1331.0(17) keV 260(20) ns IT 213Pb (21/2+)
214Pb Radium B 82 132 213.9998035(21) 27.06(7) min β− 214Bi 0+ Trace[n 19]
214mPb 1420(20) keV 6.2(3) μs IT 214Pb 8+#
215Pb 82 133 215.004662(57) 142(11) s β− 215Bi 9/2+#
216Pb 82 134 216.00806(22)# 1.66(20) min β− 216Bi 0+
216mPb 1514(20) keV 400(40) ns IT 216Pb 8+#
217Pb 82 135 217.01316(32)# 19.9(53) s β− 217Bi 9/2+#
218Pb 82 136 218.01678(32)# 14.8(68) s β− 218Bi 0+
219Pb 82 137 219.02214(43)# 3# s
[>300 ns] 		β−? 219Bi 11/2+#
220Pb 82 138 220.02591(43)# 1# s
[>300 ns] 		β−? 220Bi 0+
This table header & footer:
  1. ^ mPb – 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. ^ Modes of decay:
    EC: Electron capture
    IT: Isomeric transition
  5. ^ Bold italics symbol as daughter – Daughter product is nearly stable.
  6. ^ Bold symbol as daughter – Daughter product is stable.
  7. ^ ( ) spin value – Indicates spin with weak assignment arguments.
  8. ^ a b # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
  9. ^ a b Order of ground state and isomer is uncertain.
  10. ^ a b c Used in lead–lead dating
  11. ^ Believed to undergo α decay to 200Hg with a half-life over 1.4×1020 years; the theoretical lifetime is around ~1035–37 years.[9]
  12. ^ Final decay product of 4n+2 decay chain (the Radium or Uranium series)
  13. ^ Believed to undergo α decay to 202Hg with a half-life over 2.5×1021 years; the theoretical lifetime is ~1065–68 years.[9]
  14. ^ Final decay product of 4n+3 decay chain (the Actinium series)
  15. ^ Believed to undergo α decay to 203Hg with a half-life over 1.9×1021 years; the theoretical lifetime is ~10152–189 years.[9]
  16. ^ Heaviest observationally stable nuclide; final decay product of 4n decay chain (the Thorium series)
  17. ^ Believed to undergo α decay to 204Hg with a half-life over 2.6×1021 years; the theoretical lifetime is ~10124–132 years.[9]
  18. ^ a b Intermediate decay product of 237Np
  19. ^ a b Intermediate decay product of 238U
  20. ^ Intermediate decay product of 235U
  21. ^ Intermediate decay product of 232Th

Lead-206

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See also: Decay chain

206Pb is the final step in the decay chain of 238U, the "radium series" or "uranium series". In a closed system, over time, a given mass of 238U will decay in a sequence of steps culminating in 206Pb. The production of intermediate products eventually reaches an equilibrium (though this takes a long time, as the half-life of 234U is 245,500 years). Once this stabilized system is reached, the ratio of 238U to 206Pb will steadily decrease, while the ratios of the other intermediate products to each other remain constant.

Like most radioisotopes found in the radium series, 206Pb was initially named as a variation of radium, specifically radium G. It is the decay product of both 210Po (historically called radium F) by alpha decay, and the much rarer 206Tl (radium EII) by beta decay.

Lead-206 has been proposed for use in fast breeder nuclear fission reactor coolant over the use of natural lead mixture (which also includes other stable lead isotopes) as a mechanism to improve neutron economy and greatly suppress unwanted production of highly radioactive byproducts.[12]

Lead-204, -207, and -208

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204Pb is entirely primordial, and is thus useful for estimating the fraction of the other lead isotopes in a given sample that are also primordial, since the relative fractions of the various primordial lead isotopes is constant everywhere.[13] Any excess lead-206, -207, and -208 is thus assumed to be radiogenic in origin,[13] allowing various uranium and thorium dating schemes to be used to estimate the age of rocks (time since their formation) based on the relative abundance of lead-204 to other isotopes. 207Pb is the end of the actinium series from 235U.

208Pb is the end of the thorium series from 232Th. While it only makes up approximately half of the composition of lead in most places on Earth, it can be found naturally enriched up to around 90% in thorium ores.[14] 208Pb is the heaviest known stable nuclide and also the heaviest known doubly magic nucleus, as Z = 82 and N = 126 correspond to closed nuclear shells.[15] As a consequence of this particularly stable configuration, its neutron capture cross section is very low (even lower than that of deuterium in the thermal spectrum), making it of interest for lead-cooled fast reactors.

Lead-212

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212Pb-containing radiopharmaceuticals have been trialed as therapeutic agents for the experimental cancer treatment targeted alpha-particle therapy.[16]

References

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  1. ^ a b c d e 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. ^ Meija et al. 2016.
  3. ^ "Standard Atomic Weights: Lead". CIAAW. 2020.
  4. ^ 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.
  5. ^ Jeter, Hewitt W. (March 2000). "Determining the Ages of Recent Sediments Using Measurements of Trace Radioactivity" (PDF). Terra et Aqua (78): 21–28. Archived from the original (PDF) on March 4, 2016. Retrieved October 23, 2019.
  6. ^ Blank, B.; Regan, P.H. (2000). "Magic and doubly-magic nuclei". Nuclear Physics News. 10 (4): 20–27. doi:10.1080/10506890109411553. S2CID 121966707.
  7. ^ Takahashi, K; Boyd, R. N.; Mathews, G. J.; Yokoi, K. (October 1987). "Bound-state beta decay of highly ionized atoms". Physical Review C. 36 (4): 1522–1528. Bibcode:1987PhRvC..36.1522T. doi:10.1103/PhysRevC.36.1522. ISSN 0556-2813. OCLC 1639677. PMID 9954244. Retrieved 2016-11-20. As can be seen in Table I (187Re, 210Pb, 227Ac, and 241Pu), some continuum-state decays are energetically forbidden when the atom is fully ionized. This is because the atomic binding energies liberated by ionization, i.e., the total electron binding in the neutral atom, Bn, increases with Z. If [the decay energy] Qn<Bn(Z+1)-Bn(Z), the continuum-state β decay is energetically forbidden.
  8. ^ 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.
  9. ^ a b c d Beeman, J.W.; et al. (2013). "New experimental limits on the alpha decays of lead isotopes". European Physical Journal A. 49 (4): 50. arXiv:1212.2422. Bibcode:2013EPJA...49...50B. doi:10.1140/epja/i2013-13050-7. S2CID 254111888.
  10. ^ a b c d "Standard Atomic Weights: Lead". CIAAW. 2020.
  11. ^ Kuhn, W. (1929). "LXVIII. Scattering of thorium C" γ-radiation by radium G and ordinary lead". The London, Edinburgh, and Dublin Philosophical Magazine and Journal of Science. 8 (52): 628. doi:10.1080/14786441108564923.
  12. ^ Khorasanov, G. L.; Ivanov, A. P.; Blokhin, A. I. (2002). Polonium Issue in Fast Reactor Lead Coolants and One of the Ways of Its Solution. 10th International Conference on Nuclear Engineering. pp. 711–717. doi:10.1115/ICONE10-22330.
  13. ^ a b Woods, G.D. (November 2014). Lead isotope analysis: Removal of 204Hg isobaric interference from 204Pb using ICP-QQQ in MS/MS mode (PDF) (Report). Stockport, UK: Agilent Technologies.
  14. ^ A. Yu. Smirnov; V. D. Borisevich; A. Sulaberidze (July 2012). "Evaluation of specific cost of obtainment of lead-208 isotope by gas centrifuges using various raw materials". Theoretical Foundations of Chemical Engineering. 46 (4): 373–378. doi:10.1134/S0040579512040161. S2CID 98821122.
  15. ^ Blank, B.; Regan, P.H. (2000). "Magic and doubly-magic nuclei". Nuclear Physics News. 10 (4): 20–27. doi:10.1080/10506890109411553. S2CID 121966707.
  16. ^ Kokov, K.V.; Egorova, B.V.; German, M.N.; Klabukov, I.D.; Krasheninnikov, M.E.; Larkin-Kondrov, A.A.; Makoveeva, K.A.; Ovchinnikov, M.V.; Sidorova, M.V.; Chuvilin, D.Y. (2022). "212Pb: Production Approaches and Targeted Therapy Applications". Pharmaceutics. 14 (1): 189. doi:10.3390/pharmaceutics14010189. ISSN 1999-4923. PMC 8777968. PMID 35057083.

Sources

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Isotope masses from:

Half-life, spin, and isomer data selected from the following sources.

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