Isotopes of tellurium

There are 39 known isotopes and 17 nuclear isomers of tellurium (₅₂Te), with atomic masses that range from 104 to 142. These are listed in the table below.

Isotopes of tellurium (₅₂Te)

Main isotopes[1] Decay abun­dance half-life (t1/2) mode pro­duct 120Te 0.09% stable 121Te synth 19.31 d ε 121Sb 122Te 2.55% stable 123Te 0.89% stable[2] 124Te 4.74% stable 125Te 7.07% stable 126Te 18.8% stable 127Te synth 9.35 h β− 127I 128Te 31.7% 2.25×1024 y β−β− 128Xe 129Te synth 69.6 min β− 129I 130Te 34.1% 7.9×1020 y β−β− 130Xe
Standard atomic weight Ar°(Te)
	127.60±0.03[3] 127.60±0.03 (abridged)[4]
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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, 2.25×10²⁴ years (the longest half-life of all nuclides proven to be radioactive)^[5] and 7.9×10²⁰ years. The longest-lived artificial radioisotope of tellurium is ¹²¹Te with a half-life of 19.31 days. Several nuclear isomers have longer half-lives, the longest being ^121mTe with a half-life of 164.7 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 more recent measurements of the same team have disproved this.^[6] They have determined the half-life of ¹²³Te to be longer than 9.2 × 10¹⁶ years^[6] (or 2 × 10¹⁵ years without any theoretical assumptions). Its observational stability presents an apparent violation of the Mattauch isobar rule, the only other in nature involving ^180mTa.

¹²⁴Te is used as the starting material in the production of certain radionuclides by a cyclotron or other particle accelerator, such as iodine-123 and iodine-124.

With the exception of beryllium, tellurium is the lightest element observed to have isotopes capable of undergoing alpha decay, with isotopes ¹⁰⁴Te to ¹⁰⁹Te being seen to undergo this mode of decay. Some lighter elements, namely those in the vicinity of ⁸Be, have isotopes with delayed alpha emission (following proton or beta emission) as a rare branch.

List of isotopes

Nuclide [n 1]	Z	N	Isotopic mass (Da)[7] [n 2][n 3]	Half-life[1] [n 4][n 5]	Decay mode[1] [n 6]	Daughter isotope [n 7]	Spin and parity[1] [n 8][n 5]	Natural abundance (mole fraction)
	Excitation energy							Normal proportion[1]	Range of variation
104Te	52	52	103.94672(34)	<4 ns	α	100Sn	0+
105Te	52	53	104.94330(32)	633(66) ns	α	101Sn	(7/2+)
106Te	52	54	105.93750(11)	78(11) μs	α	102Sn	0+
107Te	52	55	106.93488(11)#	3.22(9) ms	α (70%)	103Sn	5/2+#
					β+ (30%)	107Sb
108Te	52	56	107.9293805(58)	2.1(1) s	α (49%)	104Sn	0+
					β+ (48.6%)	108Sb
					β+, p (2.4%)	107Sn
					β+, α (<0.065%)	104In
109Te	52	57	108.9273045(47)	4.4(2) s	β+ (86.7%)	109Sb	(5/2+)
					β+, p (9.4%)	108Sn
					α (3.9%)	105Sn
					β+, α (<0.0049%)	105In
110Te	52	58	109.9224581(71)	18.6(8) s	β+	110Sb	0+
111Te	52	59	110.9210006(69)	26.2(6) s	β+	111Sb	(5/2)+
					β+, p (?%)	110Sn
112Te	52	60	111.9167278(90)	2.0(2) min	β+	112Sb	0+
113Te	52	61	112.915891(30)	1.7(2) min	β+	113Sb	(7/2+)
114Te	52	62	113.912088(26)	15.2(7) min	β+	114Sb	0+
115Te	52	63	114.911902(30)	5.8(2) min	β+	115Sb	7/2+
115m1Te[n 9]	10(6) keV			6.7(4) min	β+	115Sb	(1/2+)
115m2Te	280.05(20) keV			7.5(2) μs	IT	115Te	11/2−
116Te	52	64	115.908466(26)	2.49(4) h	β+	116Sb	0+
117Te	52	65	116.908646(14)	62(2) min	EC (75%)	117Sb	1/2+
					β+ (25%)
117mTe	296.1(5) keV			103(3) ms	IT	117Te	(11/2−)
118Te	52	66	117.905860(20)	6.00(2) d	EC	118Sb	0+
119Te	52	67	118.9064057(78)	16.05(5) h	EC (97.94%)	119Sb	1/2+
					β+ (2.06%)
119mTe	260.96(5) keV			4.70(4) d	EC (99.59%)	119Sb	11/2−
					β+ (0.41%)
120Te	52	68	119.9040658(19)	Observationally Stable[n 10]			0+	9(1)×10−4
121Te	52	69	120.904945(28)	19.31(7) d	β+	121Sb	1/2+
121mTe	293.974(22) keV			164.7(5) d	IT (88.6%)	121Te	11/2−
					β+ (11.4%)	121Sb
122Te	52	70	121.9030447(15)	Stable			0+	0.0255(12)
123Te	52	71	122.9042710(15)	Observationally Stable[n 11]			1/2+	0.0089(3)
123mTe	247.47(4) keV			119.2(1) d	IT	123Te	11/2−
124Te	52	72	123.9028183(15)	Stable			0+	0.0474(14)
125Te[n 12]	52	73	124.9044312(15)	Stable			1/2+	0.0707(15)
125mTe[n 12]	144.775(8) keV			57.40(15) d	IT	125Te	11/2−
126Te	52	74	125.9033121(15)	Stable			0+	0.1884(25)
127Te[n 12]	52	75	126.9052270(15)	9.35(7) h	β−	127I	3/2+
127mTe[n 12]	88.23(7) keV			106.1(7) d	IT (97.86%)	127Te	11/2−
					β− (2.14%)	127I
128Te[n 12][n 13]	52	76	127.90446124(76)	2.25(9)×1024 y[n 14]	β−β−	128Xe	0+	0.3174(8)
128mTe	2790.8(3) keV			363(27) ns	IT	128Te	(10+)
129Te[n 12]	52	77	128.90659642(76)	69.6(3) min	β−	129I	3/2+
129mTe[n 12]	105.51(3) keV			33.6(1) d	IT (64%)	129Te	11/2−
					β− (36%)	129I
130Te[n 12][n 13]	52	78	129.906222745(11)	7.91(21)×1020 y	β−β−	130Xe	0+	0.3408(62)
130m1Te	2146.41(4) keV			186(11) ns	IT	130Te	7−
130m2Te	2667.2(8) keV			1.90(8) μs	IT	130Te	(10+)
130m3Te	4373.9(9) keV			53(8) ns	IT	130Te	(15−)
131Te[n 12]	52	79	130.908522210(65)	25.0(1) min	β−	131I	3/2+
131m1Te[n 12]	182.258(18) keV			32.48(11) h	β− (74.1%)	131I	11/2−
					IT (25.9%)	131Te
131m2Te	1940.0(4) keV			93(12) ms	IT	131Te	(23/2+)
132Te[n 12]	52	80	131.9085467(37)	3.204(13) d	β−	132I	0+
132m1Te	1774.80(9) keV			145(8) ns	IT	132Te	6+
132m2Te	1925.47(9) keV			28.5(9) μs	IT	132Te	7−
132m3Te	2723.3(8) keV			3.62(6) μs	IT	132Te	(10+)
133Te	52	81	132.9109633(22)	12.5(3) min	β−	133I	3/2+#
133m1Te	334.26(4) keV			55.4(4) min	β− (83.5%)	133I	(11/2−)
					IT (16.5%)	133Te
133m2Te	1610.4(5) keV			100(5) ns	IT	133Te	(19/2−)
134Te	52	82	133.9113964(29)	41.8(8) min	β−	134I	0+
134mTe	1691.34(16) keV			164.5(7) ns	IT	134Te	6+
135Te	52	83	134.9165547(18)	19.0(2) s	β−	135I	(7/2−)
135mTe	1554.89(16) keV			511(20) ns	IT	135Te	(19/2−)
136Te	52	84	135.9201012(24)	17.63(9) s	β− (98.63%)	136I	0+
					β−, n (1.37%)	135I
137Te	52	85	136.9255994(23)	2.49(5) s	β− (97.06%)	137I	3/2−#
					β−, n (2.94%)	136I
138Te	52	86	137.9294725(41)	1.46(25) s	β− (95.20%)	138I	0+
					β−, n (4.80%)	137I
139Te	52	87	138.9353672(38)	724(81) ms	β−	139I	5/2−#
140Te	52	88	139.939487(15)	351(5) ms	β− (?%)	140I	0+
					β−, n (?%)	139I
141Te	52	89	140.94560(43)#	193(16) ms	β−	141I	5/2−#
142Te	52	90	141.95003(54)#	147(8) ms	β−	142I	0+
143Te	52	91	142.95649(54)#	120(8) ms	β−	143I	7/2+#
144Te	52	92	143.96112(32)#	93(60) ms	β−	144I	0+
145Te	52	93	144.96778(32)#	75# ms [>550 ns]	β−	145I
This table header & footer: view

1. ^mTe – 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. Bold half-life – nearly stable, half-life longer than age of universe.
5. # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
6. Modes of decay:

   EC:	Electron capture
   IT:	Isomeric transition
   n:	Neutron emission
   p:	Proton emission

7. Bold symbol as daughter – Daughter product is stable.
8. ( ) spin value – Indicates spin with weak assignment arguments.
9. Order of ground state and isomer is uncertain.
10. Believed to undergo β⁺β⁺ decay to ¹²⁰Sn with a half-life over 1.6×10²¹ years
11. Believed to undergo electron capture to ¹²³Sb with a half-life over 9.2×10¹⁶ years
12. Fission product
13. Primordial radionuclide
14. Longest measured half-life of any nuclide

See also

Daughter products other than tellurium

• Isotopes of xenon
• Isotopes of iodine
• Isotopes of antimony
• Isotopes of tin
• Isotopes of indium