Isotopes of tellurium

There are 38 known isotopes and 17 nuclear isomers of tellurium (Te), with atomic masses that range from 105 to 142. These are listed in the table below.

Naturally-occurring tellurium on Earth consists of eight isotopes. Two of these have been found to be radioactive: ¹²⁸Te and ¹³⁰Te undergo double beta decay with half-lives of, respectively, 2.2×10²⁴ (2.2 septillion) years (the longest half-life of all nuclides proven to be radioactive)^[1] and 7.9×10²⁰ (790 quintillion) years. The longest-lived artificial radioisotope is ¹²¹Te with a half-life of nearly 19 days. Several isomers have longer half-lives, the longest being ^121mTe with a half-life of 154 days.

The very-long-lived radioisotopes ¹²⁸Te and ¹³⁰Te are the two most common isotopes of tellurium. Of elements with at least one stable isotope, only indium and rhenium likewise have a radioisotope in greater abundance than a stable one.

It has been claimed that electron capture of ¹²³Te was observed, but the recent measurements of the same team have disproved this.^[2] Tellurium-123's half life is longer than 9.2 × 10¹⁶ years, and probably much longer.^[2]

¹²⁴Te can be used as a starting material in the production of radionuclides by a cyclotron or other particle accelerators. Some common radionuclides that can be produced from tellurium-124 are iodine-123 and iodine-124.

The short-lived isotope ¹³⁵Te (half-life 19 seconds) is produced as a fission product in nuclear reactors. It decays, via two beta decays, to ¹³⁵Xe, the most powerful known neutron absorber, and the cause of the iodine pit phenomenon.

With the exception of beryllium, tellurium is the lightest element observed to commonly undergo alpha decay, with isotopes ¹⁰⁶Te to ¹¹⁰Te being seen to undergo this mode of decay. Some lighter elements have isotopes with alpha decay as a rare branch.

Tellurium's relative atomic mass is 127.60(3).

Table

nuclide symbol	Z(p)	N(n)	isotopic mass (u)	half-life[n 1]	decay mode(s)[3][n 2]	daughter isotope(s)[n 3]	nuclear spin	representative isotopic composition (mole fraction)	range of natural variation (mole fraction)
	excitation energy
^105Te	52	53	104.94364(54)#	1 µs#			5/2+#
^106Te	52	54	105.93750(14)	70(20) µs [70(+20−10) µs]	α	^102Sn	0+
^107Te	52	55	106.93501(32)#	3.1(1) ms	α (70%)	^103Sn	5/2+#
					β^+ (30%)	^107Sb
^108Te	52	56	107.92944(11)	2.1(1) s	β^+ (51%)	^108Sb	0+
					α (49%)	^104Sn
					β^+, p (2.4%)	^107Sn
					β^+, α (.065%)	^104In
^109Te	52	57	108.92742(7)	4.6(3) s	β^+ (86.99%)	^109Sb	(5/2+)
					β^+, p (9.4%)	^108Sn
					α (7.9%)	^105Sn
					β^+, α (.005%)	^105In
^110Te	52	58	109.92241(6)	18.6(8) s	β^+ (99.99%)	^110Sb	0+
					β^+, p (.003%)	^109Sn
^111Te	52	59	110.92111(8)	19.3(4) s	β^+	^111Sb	(5/2)+#
					β^+, p (rare)	^110Sn
^112Te	52	60	111.91701(18)	2.0(2) min	β^+	^112Sb	0+
^113Te	52	61	112.91589(3)	1.7(2) min	β^+	^113Sb	(7/2+)
^114Te	52	62	113.91209(3)	15.2(7) min	β^+	^114Sb	0+
^115Te	52	63	114.91190(3)	5.8(2) min	β^+	^115Sb	7/2+
^115m1Te	10(7) keV			6.7(4) min	β^+	^115Sb	(1/2)+
					IT	^115Te
^115m2Te	280.05(20) keV			7.5(2) µs			11/2−
^116Te	52	64	115.90846(3)	2.49(4) h	β^+	^116Sb	0+
^117Te	52	65	116.908645(14)	62(2) min	β^+	^117Sb	1/2+
^117mTe	296.1(5) keV			103(3) ms	IT	^117Te	(11/2−)
^118Te	52	66	117.905828(16)	6.00(2) d	EC	^118Sb	0+
^119Te	52	67	118.906404(9)	16.05(5) h	β^+	^119Sb	1/2+
^119mTe	260.96(5) keV			4.70(4) d	β^+ (99.99%)	^119Sb	11/2−
					IT (.008%)	^119Te
^120Te	52	68	119.90402(1)	Observationally Stable[n 4]			0+	9(1)×10^−4
^121Te	52	69	120.904936(28)	19.16(5) d	β^+	^121Sb	1/2+
^121mTe	293.991(22) keV			154(7) d	IT (88.6%)	^121Te	11/2−
					β^+ (11.4%)	^121Sb
^122Te	52	70	121.9030439(16)	Stable[n 5]			0+	0.0255(12)
^123Te	52	71	122.9042700(16)	Observationally Stable[n 6]			1/2+	0.0089(3)
^123mTe	247.47(4) keV			119.2(1) d	IT	^123Te	11/2−
^124Te	52	72	123.9028179(16)	Stable[n 5]			0+	0.0474(14)
^125Te[n 7]	52	73	124.9044307(16)	Stable[n 5]			1/2+	0.0707(15)
^125mTe	144.772(9) keV			57.40(15) d	IT	^125Te	11/2−
^126Te	52	74	125.9033117(16)	Stable[n 5]			0+	0.1884(25)
^127Te[n 7]	52	75	126.9052263(16)	9.35(7) h	β^−	^127I	3/2+
^127mTe	88.26(8) keV			109(2) d	IT (97.6%)	^127Te	11/2−
					β^− (2.4%)	^127I
^128Te[n 7][n 8]	52	76	127.9044631(19)	2.2(3)×10^24 y[n 9]	β^−β^−	^128Xe	0+	0.3174(8)
^128mTe	2790.7(4) keV			370(30) ns			10+
^129Te[n 7]	52	77	128.9065982(19)	69.6(3) min	β^−	^129I	3/2+
^129mTe	105.50(5) keV			33.6(1) d			11/2-
^130Te[n 7][n 8]	52	78	129.9062244(21)	790(100)×10^18 y	β^−β^−	^130Xe	0+	0.3408(62)
^130m1Te	2146.41(4) keV			115(8) ns			(7)−
^130m2Te	2661(7) keV			1.90(8) µs			(10+)
^130m3Te	4375.4(18) keV			261(33) ns
^131Te[n 7]	52	79	130.9085239(21)	25.0(1) min	β^−	^131I	3/2+
^131mTe	182.250(20) keV			30(2) h	β^− (77.8%)	^131I	11/2−
					IT (22.2%)	^131Te
^132Te[n 7]	52	80	131.908553(7)	3.204(13) d	β^−	^132I	0+
^133Te	52	81	132.910955(26)	12.5(3) min	β^−	^133I	(3/2+)
^133mTe	334.26(4) keV			55.4(4) min	β^− (82.5%)	^133I	(11/2−)
					IT (17.5%)	^133Te
^134Te	52	82	133.911369(11)	41.8(8) min	β^−	^134I	0+
^134mTe	1691.34(16) keV			164.1(9) ns			6+
^135Te[n 10]	52	83	134.91645(10)	19.0(2) s	β^−	^135I	(7/2-)
^135mTe	1554.88(17) keV			510(20) ns			(19/2−)
^136Te	52	84	135.92010(5)	17.63(8) s	β^− (98.7%)	^136I	0+
					β^−, n (1.3%)	^135I
^137Te	52	85	136.92532(13)	2.49(5) s	β^− (97.01%)	^137I	3/2−#
					β^−, n (2.99%)	^136I
^138Te	52	86	137.92922(22)#	1.4(4) s	β^− (93.7%)	^138I	0+
					β^−, n (6.3%)	^137I
^139Te	52	87	138.93473(43)#	500 ms [>300 ns]#	β^−	^139I	5/2−#
					β^−, n	^138I
^140Te	52	88	139.93885(32)#	300 ms [>300 ns]#	β^−	^140I	0+
					β^−, n	^139I
^141Te	52	89	140.94465(43)#	100 ms [>300 ns]#	β^−	^141I	5/2−#
					β^−, n	^140I
^142Te	52	90	141.94908(64)#	50 ms [>300 ns]#	β^−	^142I	0+

1. Bold for isotopes with half-lives longer than the age of the universe (nearly stable)
2. Abbreviations:
   EC: Electron capture
   IT: Isomeric transition
3. Bold for stable isotopes
4. Believed to undergo β⁺β⁺ decay to ¹²⁰Sn with a half-life over 2.2×10¹⁶ years
5. Theoretically capable of spontaneous fission
6. Believed to undergo β⁺ decay to ¹²³Sb with a half-life over 9.2×10¹⁶ years
7. Fission product
8. Primordial radionuclide
9. Longest measured half-life of any nuclide
10. Very short-lived fission product, responsible for the iodine pit as precursor of ¹³⁵Xe via ¹³⁵I

Notes

• 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

1. Many isotopes are expected to have longer half-lives, but decay has not yet been observed in these, allowing only a lower limit to be placed on their half-lives
2. A. Alessandrello; et al. (January 2003). "New Limits on Naturally Occurring Electron Capture of ¹²³Te". Physics Review C 67 (1). arXiv:hep-ex/0211015v1. doi:10.1103/PhysRevC.67.014323.
3. "Universal Nuclide Chart". nucleonica. (registration required (help)).

• Isotope masses from:
  • G. Audi; A. H. Wapstra; C. Thibault; J. Blachot (2003). "The NUBASE evaluation of nuclear and decay properties" (PDF). 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:
  • J. R. de Laeter; J. K. Böhlke; P. De Bièvre; H. Hidaka; H. S. Peiser; K. J. R. Rosman; P. D. P. Taylor (2003). "Atomic weights of the elements. Review 2000 (IUPAC Technical Report)". Pure and Applied Chemistry 75 (6): 683–800. doi:10.1351/pac200375060683.
  • M. E. Wieser (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.
  • G. Audi; A. H. Wapstra; C. Thibault; J. Blachot (2003). "The NUBASE evaluation of nuclear and decay properties" (PDF). Nuclear Physics A 729: 3–128. Bibcode:2003NuPhA.729....3A. doi:10.1016/j.nuclphysa.2003.11.001.
  • National Nuclear Data Center. "NuDat 2.1 database". Brookhaven National Laboratory. Retrieved September 2005.
  • N. E. Holden (2004). "Table of the Isotopes". In D. R. Lide. CRC Handbook of Chemistry and Physics (85th ed.). CRC Press. Section 11. ISBN 978-0-8493-0485-9.