Isotopes of thallium

Thallium (₈₁Tl) has 41 isotopes with atomic masses that range from 176 to 216. ²⁰³Tl and ²⁰⁵Tl are the only stable isotopes and ²⁰⁴Tl is the most stable radioisotope with a half-life of 3.78 years. ²⁰⁷Tl, with a half-life of 4.77 minutes, has the longest half-life of naturally occurring radioisotopes.

Main isotopes of thallium (₈₁Tl)

Iso­tope Decay abun­dance half-life (t1/2) mode pro­duct ^203Tl 29.5% stable ^204Tl syn 3.78 y β^− ^204Pb ε ^204Hg ^205Tl 70.5% stable
Standard atomic weight Ar, standard(Tl)	[204.382, 204.385][1] Conventional: 204.38

Thallium-202 (half-life 12.23 days) can be made in a cyclotron[2] while thallium-204 (half-life 3.78 years) is made by the neutron activation of stable thallium in a nuclear reactor.[3]

In the fully ionized state, the isotope ²⁰⁵Tl becomes beta-radioactive, decaying to ²⁰⁵Pb,[4] but ²⁰³Tl remains stable.

List of isotopes

Nuclide[5] [n 1]	Historic name	Z	N	Isotopic mass (Da)[6] [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
^176Tl		81	95	176.00059(21)#	5.2(+30−14) ms			(3−, 4−, 5−)
^177Tl		81	96	176.996427(27)	18(5) ms	p	^176Hg	(1/2+)
						α (rare)	^173Au
^177mTl		807(18) keV			230(40) μs	p	^176Hg	(11/2−)
						α	^173Au
^178Tl		81	97	177.99490(12)#	255(10) ms	α	^174Au
						p (rare)	^177Hg
^179Tl		81	98	178.99109(5)	270(30) ms	α	^175Au	(1/2+)
						p (rare)	^178Hg
^179mTl		860(30)# keV			1.60(16) ms	α	^175Au	(9/2−)
						IT (rare)	^179Tl
^180Tl		81	99	179.98991(13)#	1.5(2) s	α (75%)	^176Au
						β^+ (25%)	^180Hg
						EC, fission (10^−4%)	^100Ru, ^80Kr[7]
^181Tl		81	100	180.986257(10)	3.2(3) s	α	^177Au	1/2+#
						β^+	^181Hg
^181mTl		857(29) keV			1.7(4) ms	α	^177Au	9/2−#
						β^+	^181Hg
^182Tl		81	101	181.98567(8)	2.0(3) s	β^+ (96%)	^182Hg	2−#
						α (4%)	^178Au
^182m1Tl		100(100)# keV			2.9(5) s	α	^178Au	(7+)
						β^+ (rare)	^182Hg
^182m2Tl		600(140)# keV						10−
^183Tl		81	102	182.982193(10)	6.9(7) s	β^+ (98%)	^183Hg	1/2+#
						α (2%)	^179Au
^183m1Tl		630(17) keV			53.3(3) ms	IT (99.99%)	^183Tl	9/2−#
						α (.01%)	^179Au
^183m2Tl		976.8(3) keV			1.48(10) μs			(13/2+)
^184Tl		81	103	183.98187(5)	9.7(6) s	β^+	^184Hg	2−#
^184m1Tl		100(100)# keV			10# s	β^+ (97.9%)	^184Hg	7+#
						α (2.1%)	^180Au
^184m2Tl		500(140)# keV			47.1 ms	IT (99.911%)		(10−)
						α (.089%)	^180Au
^185Tl		81	104	184.97879(6)	19.5(5) s	α	^181Au	1/2+#
						β^+	^185Hg
^185mTl		452.8(20) keV			1.93(8) s	IT (99.99%)	^185Tl	9/2−#
						α (.01%)	^181Au
						β^+	^185Hg
^186Tl		81	105	185.97833(20)	40# s	β^+	^186Hg	(2−)
						α (.006%)	^182Au
^186m1Tl		320(180) keV			27.5(10) s	β^+	^186Hg	(7+)
^186m2Tl		690(180) keV			2.9(2) s			(10−)
^187Tl		81	106	186.975906(9)	~51 s	β^+	^187Hg	(1/2+)
						α (rare)	^183Au
^187mTl		335(3) keV			15.60(12) s	α	^183Au	(9/2−)
						IT	^187Tl
						β^+	^187Hg
^188Tl		81	107	187.97601(4)	71(2) s	β^+	^188Hg	(2−)
^188m1Tl		40(30) keV			71(1) s	β^+	^188Hg	(7+)
^188m2Tl		310(30) keV			41(4) ms			(9−)
^189Tl		81	108	188.973588(12)	2.3(2) min	β^+	^189Hg	(1/2+)
^189mTl		257.6(13) keV			1.4(1) min	β^+ (96%)	^189Hg	(9/2−)
						IT (4%)	^189Tl
^190Tl		81	109	189.97388(5)	2.6(3) min	β^+	^190Hg	2(−)
^190m1Tl		130(90)# keV			3.7(3) min	β^+	^190Hg	7(+#)
^190m2Tl		290(70)# keV			750(40) μs			(8−)
^190m3Tl		410(70)# keV			>1 μs			9−
^191Tl		81	110	190.971786(8)	20# min	β^+	^191Hg	(1/2+)
^191mTl		297(7) keV			5.22(16) min	β^+	^191Hg	9/2(−)
^192Tl		81	111	191.97223(3)	9.6(4) min	β^+	^192Hg	(2−)
^192m1Tl		160(50) keV			10.8(2) min	β^+	^192Hg	(7+)
^192m2Tl		407(54) keV			296(5) ns			(8−)
^193Tl		81	112	192.97067(12)	21.6(8) min	β^+	^193Hg	1/2(+#)
^193mTl		369(4) keV			2.11(15) min	IT (75%)	^193Tl	9/2−
						β^+ (25%)	^193Hg
^194Tl		81	113	193.97120(15)	33.0(5) min	β^+	^194Hg	2−
						α (10^−7%)	^190Au
^194mTl		300(200)# keV			32.8(2) min	β^+	^194Hg	(7+)
^195Tl		81	114	194.969774(15)	1.16(5) h	β^+	^195Hg	1/2+
^195mTl		482.63(17) keV			3.6(4) s	IT	^195Tl	9/2−
^196Tl		81	115	195.970481(13)	1.84(3) h	β^+	^196Hg	2−
^196mTl		394.2(5) keV			1.41(2) h	β^+ (95.5%)	^196Hg	(7+)
						IT (4.5%)	^196Tl
^197Tl		81	116	196.969575(18)	2.84(4) h	β^+	^197Hg	1/2+
^197mTl		608.22(8) keV			540(10) ms	IT	^197Tl	9/2−
^198Tl		81	117	197.97048(9)	5.3(5) h	β^+	^198Hg	2−
^198m1Tl		543.5(4) keV			1.87(3) h	β^+ (54%)	^198Hg	7+
						IT (46%)	^198Tl
^198m2Tl		687.2(5) keV			150(40) ns			(5+)
^198m3Tl		742.3(4) keV			32.1(10) ms			(10−)#
^199Tl		81	118	198.96988(3)	7.42(8) h	β^+	^199Hg	1/2+
^199mTl		749.7(3) keV			28.4(2) ms	IT	^199Tl	9/2−
^200Tl		81	119	199.970963(6)	26.1(1) h	β^+	^200Hg	2−
^200m1Tl		753.6(2) keV			34.3(10) ms	IT	^200Tl	7+
^200m2Tl		762.0(2) keV			0.33(5) μs			5+
^201Tl[n 8]		81	120	200.970819(16)	72.912(17) h	EC	^201Hg	1/2+
^201mTl		919.50(9) keV			2.035(7) ms	IT	^201Tl	(9/2−)
^202Tl		81	121	201.972106(16)	12.23(2) d	β^+	^202Hg	2−
^202mTl		950.19(10) keV			572(7) μs			7+
^203Tl		81	122	202.9723442(14)	Stable			1/2+	0.2952(1)	0.29494–0.29528
^203mTl		3400(300) keV			7.7(5) μs			(25/2+)
^204Tl		81	123	203.9738635(13)	3.78(2) y	β^− (97.1%)	^204Pb	2−
						EC (2.9%)	^204Hg
^204m1Tl		1104.0(4) keV			63(2) μs			(7)+
^204m2Tl		2500(500) keV			2.6(2) μs			(12−)
^204m3Tl		3500(500) keV			1.6(2) μs			(20+)
^205Tl[n 9]		81	124	204.9744275(14)	Stable			1/2+	0.7048(1)	0.70472–0.70506
^205m1Tl		3290.63(17) keV			2.6(2) μs			25/2+
^205m2Tl		4835.6(15) keV			235(10) ns			(35/2–)
^206Tl	Radium E	81	125	205.9761103(15)	4.200(17) min	β^−	^206Pb	0−	Trace[n 10]
^206mTl		2643.11(19) keV			3.74(3) min	IT	^206Tl	(12–)
^207Tl	Actinium C	81	126	206.977419(6)	4.77(2) min	β^−	^207Pb	1/2+	Trace[n 11]
^207mTl		1348.1(3) keV			1.33(11) s	IT (99.9%)	^207Tl	11/2–
						β^− (.1%)	^207Pb
^208Tl	Thorium C"	81	127	207.9820187(21)	3.053(4) min	β^−	^208Pb	5+	Trace[n 12]
^209Tl		81	128	208.985359(8)	2.161(7) min	β^−	^209Pb	1/2+	Trace[n 13]
^210Tl	Radium C″	81	129	209.990074(12)	1.30(3) min	β^− (99.991%)	^210Pb	(5+)#	Trace[n 10]
						β^−, n (.009%)	^209Pb
^211Tl		81	130	210.993480(50)	80(16) s	β^− (97.8%)	^211Pb	1/2+
						β^−, n (2.2%)	^210Pb
^212Tl		81	131	211.998340(220)#	31(8) s	β^− (98.2%)	^212Pb	(5+)
						β^−, n (1.8%)	^211Pb
^213Tl		81	132	213.001915(29)	24(4) s	β^− (92.4%)	^213Pb	1/2+
						β^−, n (7.6%)	^212Pb
^214Tl		81	133	214.006940(210)#	11(2) s	β^− (66%)	^214Pb	5+#
						β^−, n (34%)	^213Pb
^215Tl		81	134	215.010640(320)#	10(4) s	β^− (95.4%)	^215Pb	1/2+#
						β^−, n (4.6%)	^214Pb
^216Tl		81	135	216.015800(320)#	6(3) s	β^−	^216Pb	5+#
						β^−, n (<11.5%)	^215Pb

1. ^mTl – 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
   n:	Neutron emission
   p:	Proton emission

6. Bold symbol as daughter – Daughter product is stable.
7. ( ) spin value – Indicates spin with weak assignment arguments.
8. Main isotope used in scintigraphy
9. Final decay product of 4n+1 decay chain (the Neptunium series)
10. Intermediate decay product of ²³⁸U
11. Intermediate decay product of ²³⁵U
12. Intermediate decay product of ²³²Th
13. Intermediate decay product of ²³⁷Np

Thallium-201

Radiopharmaceutical.

References

1. Meija, Juris; et al. (2016). "Atomic weights of the elements 2013 (IUPAC Technical Report)". Pure and Applied Chemistry. 88 (3): 265–91. doi:10.1515/pac-2015-0305.
2. "Thallium Research". doe.gov. Department of Energy. Archived from the original on 2006-12-09. Retrieved 23 March 2018.
3. Manual for reactor produced radioisotopes from the International Atomic Energy Agency
4. "Bound-state beta decay of highly ionized atoms" (PDF). Archived from the original (PDF) on October 29, 2013. Retrieved June 9, 2013.
5. 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.
6. 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.
7. Reich, E. S. (2010). "Mercury serves up a nuclear surprise: a new type of fission". Scientific American. Retrieved 12 May 2011.

• 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.