Isotopes of lead

Lead (₈₂Pb) 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: 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, respectively. However, each of them 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).

Main isotopes of lead (₈₂Pb)

Iso­tope Decay abun­dance half-life (t1/2) mode pro­duct ^202Pb syn 5.25(28)×10^4 y ε ^202Tl ^204Pb 1.4% stable ^205Pb trace 1.73(7)×10^7 y ε ^205Tl ^206Pb 24.1% stable ^207Pb 22.1% stable ^208Pb 52.4% stable ^209Pb trace 3.253(14) h β^− ^209Bi ^210Pb trace 22.3(22) y β^− ^210Bi ^211Pb trace 36.1(2) min β^− ^211Bi ^212Pb trace 10.64(1) h β^− ^212Bi ^214Pb trace 26.8(9) min β^− ^214Bi Isotopic abundances vary greatly by sample
Standard atomic weight Ar, standard(Pb)	207.2(1)[1]

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 22.3 years, is useful for studying the sedimentation chronology of environmental samples on time scales shorter than 100 years.[2]

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.) A total of 43 lead isotopes are now known, including very unstable synthetic species.

In its fully ionized state, the isotope ²⁰⁵Pb also becomes stable.[3]

List of isotopes

Nuclide[4] [n 1]	Historic name	Z	N	Isotopic mass (Da)[5] [n 2][n 3]	Half-life	Decay mode [n 4]	Daughter isotope [n 5][n 6]	Spin and parity [n 7][n 8]	Natural abundance (mole fraction)
		Excitation energy[n 8]							Normal proportion	Range of variation
^178Pb		82	96	178.003830(26)	0.23(15) ms	α	^174Hg	0+
^179Pb		82	97	179.00215(21)#	3.9(1.1) ms	α	^175Hg	(9/2−)
^180Pb		82	98	179.997918(22)	4.5(11) ms	α	^176Hg	0+
^181Pb		82	99	180.99662(10)	45(20) ms	α (98%)	^177Hg	(9/2−)
						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−)
^189m1Pb		40(30)# keV			50.5(2.1) s	β^+ (99.6%)	^189Tl	13/2+
						α (.4%)	^185Hg
^189m2Pb		2475(30)# keV			26(5) µs			(10)+
^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%)	^201Tl	5/2−
						β^+ (1%)
^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)	5.25(28)×10^4 y	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 9]		82	122	203.9730436(13)	Observationally Stable[n 10]			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)	1.73(7)×10^7 y	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 9][n 11]	Radium G	82	124	205.9744653(13)	Observationally Stable[n 12]			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 9][n 13]	Actinium D	82	125	206.9758969(13)	Observationally Stable[n 14]			1/2−	0.221(1)	0.1762–0.2365
^207mPb		1633.368(5) keV			806(6) ms	IT	^207Pb	13/2+
^208Pb[n 15]	Thorium D	82	126	207.9766521(13)	Observationally Stable[n 16]			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 17]
^210Pb	Radium D Radiolead Radio-lead	82	128	209.9841885(16)	22.3(22) y	β^− (100%)	^210Bi	0+	Trace[n 18]
						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 19]
^212Pb	Thorium B	82	130	211.9918975(24)	10.64(1) h	β^−	^212Bi	0+	Trace[n 20]
^212mPb		1335(10) keV			6.0(0.8) µs	IT	^212Pb	(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 18]
^214mPb		1420(20) keV			6.2(0.3) µs	IT	^212Pb	8+#
^215Pb		82	133	215.004660(60)	2.34(0.19) min	β^−	^215Bi	9/2+#
^216Pb		82	134	216.008030(210)#	1.65(0.2) min	β^−	^216Bi	0+
^216mPb		1514(20) keV			400(40) ns	IT	^216Pb	8+#
^217Pb		82	135	217.013140(320)#	20(5) s	β^−	^217Bi	9/2+#
^218Pb		82	136	218.016590(320)#	15(7) s	β^−	^218Bi	0+

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. # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
9. Used in lead-lead dating
10. Believed to undergo α decay to ²⁰⁰Hg with a half-life over 1.4×10²⁰ years
11. Final decay product of 4n+2 decay chain (the Radium or Uranium series)
12. Believed to undergo α decay to ²⁰²Hg with a half-life over 2.5×10²¹ years
13. Final decay product of 4n+3 decay chain (the Actinium series)
14. Believed to undergo α decay to ²⁰³Hg with a half-life over 1.9×10²¹ years
15. Final decay product of 4n decay chain (the Thorium series)
16. Heaviest observationally stable nuclide, believed to undergo α decay to ²⁰⁴Hg with a half-life over 2.6×10²¹ years
17. Intermediate decay product of ²³⁷Np
18. Intermediate decay product of ²³⁸U
19. Intermediate decay product of ²³⁵U
20. Intermediate decay product of ²³²Th

Lead-206

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 E^II) 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.[6]

Lead-204, -207, and -208

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.[7] Any excess lead-206, -207, and -208 is thus assumed to be radiogenic in origin,[7] 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.[8] ²⁰⁸Pb is the heaviest known stable isotope of any element, and also the heaviest known doubly magic nucleus, as Z = 82 and N = 126 correspond to closed nuclear shells.[9] 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.

References

1. Meija et al. 2016. sfn error: no target: CITEREFMeijaCoplenBerglundBrand2016 (help)
2. Jeter, Hewitt W. (March 2000). "Determining the Ages of Recent Sediments Using Measurements of Trace Radioactivity" (PDF). Terra et Aqua (78): 21–28. Retrieved October 23, 2019.
3. 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.
4. Half-life, decay mode, nuclear spin, and isotopic composition is sourced in:
   Audi, G.; Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S. (2017). "The NUBASE2016 evaluation of nuclear properties" (PDF). Chinese Physics C. 41 (3): 030001. Bibcode:2017ChPhC..41c0001A. doi:10.1088/1674-1137/41/3/030001.
5. Wang, M.; Audi, G.; Kondev, F. G.; Huang, W. J.; Naimi, S.; Xu, X. (2017). "The AME2016 atomic mass evaluation (II). Tables, graphs, and references" (PDF). Chinese Physics C. 41 (3): 030003-1–030003-442. doi:10.1088/1674-1137/41/3/030003.
6. 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.
7. 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.
8. 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.
9. Blank, B.; Regan, P.H. (2000). "Magic and doubly-magic nuclei". Nuclear Physics News. 10 (4): 20–27. doi:10.1080/10506890109411553. S2CID 121966707.

Isotope masses from:

• Audi, Georges; Bersillon, Olivier; Blachot, Jean; Wapstra, Aaldert Hendrik (2003), "The NUBASE evaluation of nuclear and decay properties", Nuclear Physics A, 729: 3–128, Bibcode:2003NuPhA.729....3A, doi:10.1016/j.nuclphysa.2003.11.001

Isotopic compositions and standard atomic masses from:

• de Laeter, John Robert; Böhlke, John Karl; De Bièvre, Paul; Hidaka, Hiroshi; Peiser, H. Steffen; Rosman, Kevin J. R.; Taylor, Philip D. P. (2003). "Atomic weights of the elements. Review 2000 (IUPAC Technical Report)". Pure and Applied Chemistry. 75 (6): 683–800. doi:10.1351/pac200375060683.
• Wieser, Michael E. (2006). "Atomic weights of the elements 2005 (IUPAC Technical Report)". Pure and Applied Chemistry. 78 (11): 2051–2066. doi:10.1351/pac200678112051. Lay summary.

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

• Audi, Georges; Bersillon, Olivier; Blachot, Jean; Wapstra, Aaldert Hendrik (2003), "The NUBASE evaluation of nuclear and decay properties", Nuclear Physics A, 729: 3–128, Bibcode:2003NuPhA.729....3A, doi:10.1016/j.nuclphysa.2003.11.001
• National Nuclear Data Center. "NuDat 2.x database". Brookhaven National Laboratory.
• Holden, Norman E. (2004). "11. Table of the Isotopes". In Lide, David R. (ed.). CRC Handbook of Chemistry and Physics (85th ed.). Boca Raton, Florida: CRC Press. ISBN 978-0-8493-0485-9.