isotopes of thallium

Thallium (Tl) has 25 isotopes which have atomic masses that range from 184 to 210. ²⁰³Tl and ²⁰⁵Tl are the only stable isotopes and ²⁰⁴Tl is the most stable radioisotope with a half-life of 3.78 years.

Thallium-202 (half life 12.23 days) can be made in a cyclotron^[1] while thallium-204 (half life 3.78 years) is made by the neutron activation of stable thallium in a nuclear reactor.^[2]

Standard atomic mass: 204.3833(2) u

Isotopes of thallium occurring within the radioactive disintegration chains of actinium, radium and thorium were known as:

radium E^II : ²⁰⁶Tl
actinium C^II : ²⁰⁷Tl
thorium C^II : ²⁰⁸Tl
radium C^II : ²¹⁰Tl

Table

nuclide symbol	Z(p)	N(n)	isotopic mass (u)	half-life	nuclear spin	representative isotopic composition (mole fraction)	range of natural variation (mole fraction)	other features
nuclide symbol	excitation energy			half-life	nuclear spin	representative isotopic composition (mole fraction)	range of natural variation (mole fraction)	other features
¹⁷⁶Tl	81	95	176.00059(21)#	5.2(+30-14) ms	(3-,4-,5-)
¹⁷⁷Tl	81	100	176.996427(27)	18(5) ms	(1/2+)
^177mTl	807(18) keV			230(40) µs	(11/2-)
¹⁷⁸Tl	81	97	177.99490(12)#	255(10) ms
¹⁷⁹Tl	81	98	178.99109(5)	270(30) ms	(1/2+)
^179mTl	860(30)# keV			1.60(16) ms	(9/2-)
¹⁸⁰Tl	81	99	179.98991(13)#	1.5(2) s
¹⁸¹Tl	81	100	180.986257(10)	3.2(3) s	1/2+#
^181mTl	857(29) keV			1.7(4) ms	9/2-#
¹⁸²Tl	81	101	181.98567(8)	2.0(3) s	2-#
^182m1Tl	100(100)# keV			2.9(5) s	(7+)
^182m2Tl	600(140)# keV				10-
¹⁸³Tl	81	102	182.982193(10)	6.9(7) s	1/2+#
^183m1Tl	630(17) keV			53.3(3) ms	9/2-#
^183m2Tl	976.8(3) keV			1.48(10) µs	(13/2+)
¹⁸⁴Tl	81	103	183.98187(5)	9.7(6) s	2-#
^184m1Tl	100(100)# keV			10# s	7+#
^184m2Tl	500(140)# keV			>20 ns	(10-)
¹⁸⁵Tl	81	104	184.97879(6)	19.5(5) s	1/2+#
^185mTl	452.8(20) keV			1.93(8) s	9/2-#
¹⁸⁶Tl	81	105	185.97833(20)	40# s	(2-)
^186m1Tl	320(180) keV			27.5(10) s	(7+)
^186m2Tl	690(180) keV			2.9(2) s	(10-)
¹⁸⁷Tl	81	106	186.975906(9)	~51 s	(1/2+)
^187mTl	335(3) keV			15.60(12) s	(9/2-)
¹⁸⁸Tl	81	107	187.97601(4)	71(2) s	(2-)
^188m1Tl	40(30) keV			71(1) s	(7+)
^188m2Tl	310(30) keV			41(4) ms	(9-)
¹⁸⁹Tl	81	108	188.973588(12)	2.3(2) min	(1/2+)
^189mTl	257.6(13) keV			1.4(1) min	(9/2-)
¹⁹⁰Tl	81	109	189.97388(5)	2.6(3) min	2(-)
^190m1Tl	130(90)# keV			3.7(3) min	7(+#)
^190m2Tl	290(70)# keV			750(40) µs	(8-)
^190m3Tl	410(70)# keV			>1 µs	9-
¹⁹¹Tl	81	110	190.971786(8)	20# min	(1/2+)
^191mTl	297(7) keV			5.22(16) min	9/2(-)
¹⁹²Tl	81	111	191.97223(3)	9.6(4) min	(2-)
^192m1Tl	160(50) keV			10.8(2) min	(7+)
^192m2Tl	407(54) keV			296(5) ns	(8-)
¹⁹³Tl	81	112	192.97067(12)	21.6(8) min	1/2(+#)
^193mTl	369(4) keV			2.11(15) min	9/2-
¹⁹⁴Tl	81	113	193.97120(15)	33.0(5) min	2-
^194mTl	300(200)# keV			32.8(2) min	(7+)
¹⁹⁵Tl	81	114	194.969774(15)	1.16(5) h	1/2+
^195mTl	482.63(17) keV			3.6(4) s	9/2-
¹⁹⁶Tl	81	115	195.970481(13)	1.84(3) h	2-
^196mTl	394.2(5) keV			1.41(2) h	(7+)
¹⁹⁷Tl	81	116	196.969575(18)	2.84(4) h	1/2+
^197mTl	608.22(8) keV			540(10) ms	9/2-
¹⁹⁸Tl	81	117	197.97048(9)	5.3(5) h	2-
^198m1Tl	543.5(4) keV			1.87(3) h	7+
^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	1/2+
^199mTl	749.7(3) keV			28.4(2) ms	9/2-
²⁰⁰Tl	81	119	199.970963(6)	26.1(1) h	2-
^200m1Tl	753.6(2) keV			34.3(10) ms	7+
^200m2Tl	762.0(2) keV			0.33(5) µs	5+
²⁰¹Tl	81	120	200.970819(16)	72.912(17) h	1/2+			Main isotope used in scintigraphy
^201mTl	919.50(9) keV			2.035(7) ms	(9/2-)
²⁰²Tl	81	121	201.972106(16)	12.23(2) d	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	One of the two stable thallium isotopes
^203mTl	3400(300) keV			7.7(5) µs	(25/2+)
²⁰⁴Tl	81	123	203.9738635(13)	3.78(2) a	2-			Most stable thallium radioisotope
^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	81	124	204.9744275(14)	STABLE	1/2+	0.7048(1)	0.70472-0.70506	One of the two stable thallium isotopes
^205m1Tl	3290.63(17) keV			2.6(2) µs	25/2+
^205m2Tl	4835.6(15) keV			235(10) ns	(35/2-)
²⁰⁶Tl	81	125	205.9761103(15)	4.200(17) min	0-
^206mTl	2643.11(19) keV			3.74(3) min	(12-)
²⁰⁷Tl	81	126	206.977419(6)	4.77(2) min	1/2+
^207mTl	1348.1(3) keV			1.33(11) s	11/2-
²⁰⁸Tl	81	127	207.9820187(21)	3.053(4) min	5(+)
²⁰⁹Tl	81	128	208.985359(8)	2.161(7) min	(1/2+)
²¹⁰Tl	81	129	209.990074(12)	1.30(3) min	(5+)#
²¹¹Tl	81	130	210.99348(22)#	1# min [>300 ns]	1/2+#
²¹²Tl	81	131	211.99823(32)#	30# s [>300 ns]	5+#

Notes

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

Isotope masses from:
- G. Audi, A. H. Wapstra, C. Thibault, J. Blachot and O. Bersillon (2003). . Nuclear Physics A 729: 3–128. . http://www.nndc.bnl.gov/amdc/nubase/Nubase2003.pdf.
Isotopic compositions and standard atomic masses from:
- J. R. de Laeter, J. K. Böhlke, P. De Bièvre, H. Hidaka, H. S. Peiser, K. J. R. Rosman and P. D. P. Taylor (2003). . Pure and Applied Chemistry 75 (6): 683–800. . http://www.iupac.org/publications/pac/75/6/0683/pdf/.
- M. E. Wieser (2006). . Pure and Applied Chemistry 78 (11): 2051–2066. . http://iupac.org/publications/pac/78/11/2051/pdf/. Lay summary.
Half-life, spin, and isomer data selected from the following sources. See editing notes on this article's talk page.
- G. Audi, A. H. Wapstra, C. Thibault, J. Blachot and O. Bersillon (2003). . Nuclear Physics A 729: 3–128. . http://www.nndc.bnl.gov/amdc/nubase/Nubase2003.pdf.
- National Nuclear Data Center. . Brookhaven National Laboratory. http://www.nndc.bnl.gov/nudat2/. Retrieved September 2005.
- N. E. Holden (2004). . In D. R. Lide. (85th ed.). CRC Press. Section 11. .

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