Isotopes of lead

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Lead (Pb) has four 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 called the uranium series (or radium series), the actinium series, and the thorium series, respectively. These series represent the decay chain products of long-lived primordial U-238, U-235, and Th-232, respectively. However, each of them also occurs, to some extent, as primordial isotopes which 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).

The longest-lived radioisotopes are 205Pb with a half-life of ~15.3 million years and 202Pb with a half-life of ~53,000 years. Of naturally-occurring radioisotopes, the shortest half-life is 210Pb with a half-life of 22.20 years.

The standard atomic mass (abundance-weighted average of the stable isotopes) is 207.2(1) u. 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 1.9×1019 years). A total of 38 Pb isotopes are now known, including very unstable synthetic species.

In its fully ionized state the isotope 205Pb also becomes stable.[1]

Lead-206[edit]

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 more rare 206Tl (radium EII) by beta decay.

Lead 207, 208, and 204[edit]

207Pb is the end of the Actinium series from 235U.

208Pb is the end of the Thorium series from 232Th.

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).[citation needed] Any excess lead 206, 207, and 208 is thus assumed to be radiogenic in origin[citation needed], allowing various uranium and thorium dating schemes to be used to estimate the age of rocks (time since their formation).

Table[edit]

nuclide
symbol
historic
name
Z(p) N(n)  
isotopic mass (u)
 
half-life decay
mode(s)[2][n 1]
daughter
isotope(s)[n 2]
nuclear
spin
representative
isotopic
composition
(mole fraction)
range of natural
variation
(mole fraction)
excitation energy
178Pb 82 96 178.003830(26) 0.23(15) ms 0+
179Pb 82 97 179.00215(21)# 3# ms 5/2-#
180Pb 82 98 179.997918(22) 4.5(11) ms 0+
181Pb 82 99 180.99662(10) 45(20) ms α (98%) 177Hg 5/2-#
β+ (2%) 181Tl
182Pb 82 100 181.992672(15) 60(40) ms
[55(+40-35) ms]
α (98%) 178Hg 0+
β+ (2%) 182Tl
183Pb 82 101 182.99187(3) 535(30) ms α (94%) 179Hg (3/2-)
β+ (6%) 183Tl
183mPb 94(8) keV 415(20) ms α 179Hg (13/2+)
β+ (rare) 183Tl
184Pb 82 102 183.988142(15) 490(25) ms α 180Hg 0+
β+ (rare) 184Tl
185Pb 82 103 184.987610(17) 6.3(4) s α 181Hg 3/2-
β+ (rare) 185Tl
185mPb 60(40)# keV 4.07(15) s α 181Hg 13/2+
β+ (rare) 185Tl
186Pb 82 104 185.984239(12) 4.82(3) s α (56%) 182Hg 0+
β+ (44%) 186Tl
187Pb 82 105 186.983918(9) 15.2(3) s β+ 187Tl (3/2-)
α 183Hg
187mPb 11(11) keV 18.3(3) s β+ (98%) 187Tl (13/2+)
α (2%) 183Hg
188Pb 82 106 187.980874(11) 25.5(1) s β+ (91.5%) 188Tl 0+
α (8.5%) 184Hg
188m1Pb 2578.2(7) keV 830(210) ns (8-)
188m2Pb 2800(50) keV 797(21) ns
189Pb 82 107 188.98081(4) 51(3) s β+ 189Tl (3/2-)
189mPb 40(30)# keV 1# min β+ (99.6%) 189Tl (13/2+)
α (.4%) 185Hg
190Pb 82 108 189.978082(13) 71(1) s β+ (99.1%) 190Tl 0+
α (.9%) 186Hg
190m1Pb 2614.8(8) keV 150 ns (10)+
190m2Pb 2618(20) keV 25 µs (12+)
190m3Pb 2658.2(8) keV 7.2(6) µs (11)-
191Pb 82 109 190.97827(4) 1.33(8) min β+ (99.987%) 191Tl (3/2-)
α (.013%) 187Hg
191mPb 20(50) keV 2.18(8) min β+ (99.98%) 191Tl 13/2(+)
α (.02%) 187Hg
192Pb 82 110 191.975785(14) 3.5(1) min β+ (99.99%) 192Tl 0+
α (.0061%) 188Hg
192m1Pb 2581.1(1) keV 164(7) ns (10)+
192m2Pb 2625.1(11) keV 1.1(5) µs (12+)
192m3Pb 2743.5(4) keV 756(21) ns (11)-
193Pb 82 111 192.97617(5) 5# min β+ 193Tl (3/2-)
193m1Pb 130(80)# keV 5.8(2) min β+ 193Tl 13/2(+)
193m2Pb 2612.5(5)+X keV 135(+25-15) ns (33/2+)
194Pb 82 112 193.974012(19) 12.0(5) min β+ (100%) 194Tl 0+
α (7.3×10−6%) 190Hg
195Pb 82 113 194.974542(25) ~15 min β+ 195Tl 3/2#-
195m1Pb 202.9(7) keV 15.0(12) min β+ 195Tl 13/2+
195m2Pb 1759.0(7) keV 10.0(7) µs 21/2-
196Pb 82 114 195.972774(15) 37(3) min β+ 196Tl 0+
α (3×10−5%) 192Hg
196m1Pb 1049.20(9) keV <100 ns 2+
196m2Pb 1738.27(12) keV <1 µs 4+
196m3Pb 1797.51(14) keV 140(14) ns 5-
196m4Pb 2693.5(5) keV 270(4) ns (12+)
197Pb 82 115 196.973431(6) 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
α (3×10−4%) 193Hg
197m2Pb 1914.10(25) keV 1.15(20) µs 21/2-
198Pb 82 116 197.972034(16) 2.4(1) h β+ 198Tl 0+
198m1Pb 2141.4(4) keV 4.19(10) µs (7)-
198m2Pb 2231.4(5) keV 137(10) ns (9)-
198m3Pb 2820.5(7) keV 212(4) ns (12)+
199Pb 82 117 198.972917(28) 90(10) min β+ 199Tl 3/2-
199m1Pb 429.5(27) keV 12.2(3) min IT (93%) 199Pb (13/2+)
β+ (7%) 199Tl
199m2Pb 2563.8(27) keV 10.1(2) µs (29/2-)
200Pb 82 118 199.971827(12) 21.5(4) h β+ 200Tl 0+
201Pb 82 119 200.972885(24) 9.33(3) h EC (99%) 201Pb 5/2-
β+ (1%) 201Tl
201m1Pb 629.14(17) keV 61(2) s 13/2+
201m2Pb 2718.5+X keV 508(5) ns (29/2-)
202Pb 82 120 201.972159(9) 52.5(28)×103 a EC (99%) 202Tl 0+
α (1%) 198Hg
202m1Pb 2169.83(7) keV 3.53(1) h IT (90.5%) 202Pb 9-
EC (9.5%) 202Tl
202m2Pb 4142.9(11) keV 110(5) ns (16+)
202m3Pb 5345.9(13) keV 107(5) ns (19-)
203Pb 82 121 202.973391(7) 51.873(9) h EC 203Tl 5/2-
203m1Pb 825.20(9) keV 6.21(8) s IT 203Pb 13/2+
203m2Pb 2949.47(22) keV 480(7) ms 29/2-
203m3Pb 2923.4+X keV 122(4) ns (25/2-)
204Pb[n 3] 82 122 203.9730436(13) Observationally Stable[n 4] 0+ 0.014(1) 0.0104-0.0165
204m1Pb 1274.00(4) keV 265(10) ns 4+
204m2Pb 2185.79(5) keV 67.2(3) min 9-
204m3Pb 2264.33(4) keV 0.45(+10-3) µs 7-
205Pb 82 123 204.9744818(13) 15.3(7)×106 a EC 205Tl 5/2-
205m1Pb 2.329(7) keV 24.2(4) µs 1/2-
205m2Pb 1013.839(13) keV 5.55(2) ms 13/2+
205m3Pb 3195.7(5) keV 217(5) ns 25/2-
206Pb[n 3][n 5] Radium G 82 124 205.9744653(13) Observationally Stable[n 6] 0+ 0.241(1) 0.2084-0.2748
206m1Pb 2200.14(4) keV 125(2) µs 7-
206m2Pb 4027.3(7) keV 202(3) ns 12+
207Pb[n 3][n 7] Actinium D 82 125 206.9758969(13) Observationally Stable[n 8] 1/2- 0.221(1) 0.1762-0.2365
207mPb 1633.368(5) keV 806(6) ms IT 207Pb 13/2+
208Pb[n 9] Thorium D 82 126 207.9766521(13) Observationally Stable[n 10] 0+ 0.524(1) 0.5128-0.5621
208mPb 4895(2) keV 500(10) ns 10+
209Pb 82 127 208.9810901(19) 3.253(14) h β- 209Bi 9/2+ Trace[n 11]
210Pb Radium D
Radiolead
Radio-lead
82 128 209.9841885(16) 22.20(22) a β- (100%) 210Bi 0+ Trace[n 12]
α (1.9×10−6%) 206Hg
210mPb 1278(5) keV 201(17) ns 8+
211Pb Actinium B 82 129 210.9887370(29) 36.1(2) min β- 211Bi 9/2+ Trace[n 13]
212Pb Thorium B 82 130 211.9918975(24) 10.64(1) h β- 212Bi 0+ Trace[n 14]
212mPb 1335(10) keV 5(1) µs (8+)
213Pb 82 131 212.996581(8) 10.2(3) min β- 213Bi (9/2+)
214Pb Radium B 82 132 213.9998054(26) 26.8(9) min β- 214Bi 0+ Trace[n 12]
215Pb 82 133 215.00481(44)# 36(1) s 5/2+#
  1. ^ Abbreviations:
    EC: Electron capture
    IT: Isomeric transition
  2. ^ Bold for stable isotopes, bold italics for nearly-stable isotopes (half-life longer than the age of the universe)
  3. ^ a b c Used in lead-lead dating
  4. ^ Believed to undergo α decay to 200Hg with a half-life over 140×1015 years
  5. ^ Final decay product of 4n+2 decay chain (the Radium or Uranium series)
  6. ^ Believed to undergo α decay to 202Hg
  7. ^ Final decay product of 4n+3 decay chain (the Actinium series)
  8. ^ Believed to undergo α decay to 203Hg
  9. ^ Final decay product of 4n decay chain (the Thorium series)
  10. ^ Heaviest observationally stable nuclide, believed to undergo α decay to 204Hg with a half-life over 2×1019 years
  11. ^ Cluster decay product of 223Ra which occurs in the decay chain of 235U
  12. ^ a b Intermediate decay product of 238U
  13. ^ Intermediate decay product of 235U
  14. ^ Intermediate decay product of 232Th

Notes[edit]

  • Evaluated isotopic composition is for most but not all commercial samples.
  • The precision of the isotope abundances and atomic mass is limited through variations. The given ranges should be applicable to any normal terrestrial material.
  • Geologically exceptional samples are known in which the isotopic composition lies outside the reported range. The uncertainty in the atomic mass may exceed the stated value for such specimens.
  • Values marked # are not purely derived from experimental data, but at least partly from systematic trends. Spins with weak assignment arguments are enclosed in parentheses.
  • Uncertainties are given in concise form in parentheses after the corresponding last digits. Uncertainty values denote one standard deviation, except isotopic composition and standard atomic mass from IUPAC which use expanded uncertainties.

References[edit]

  1. ^ Takahashi, K; Boyd, R. N.; Mathews, G. J.; Yokoi, K. (October 1987). "Bound-state beta decay of highly ionized atoms". Physical Review C (New York, NY: American Institute of Physics for the American Physical Society) 36 (4). ISSN 0556-2813. OCLC 1639677. Retrieved 2013-08-27. 
  2. ^ "Universal Nuclide Chart". Nucleonica. Retrieved 2013-08-28. 


Isotopes of thallium Isotopes of lead Isotopes of bismuth
Table of nuclides