There are 39 known

isotope Isotopes are two or more types of atoms that have the same atomic number (number of protons in their nuclei) and position in the periodic table (and hence belong to the same chemical element), and that differ in nucleon numbers (mass numbers) ...

s and 17

nuclear isomer A nuclear isomer is a metastable state of an atomic nucleus, in which one or more nucleons (protons or neutrons) occupy excited state, higher energy levels than in the ground state of the same nucleus. "Metastable" describes nuclei whose excited ...

s of

tellurium Tellurium is a chemical element with the symbol Te and atomic number 52. It is a brittle, mildly toxic, rare, silver-white metalloid. Tellurium is chemically related to selenium and sulfur, all three of which are chalcogens. It is occasionally fou ...

(₅₂Te), with

atomic mass The atomic mass (''m''a or ''m'') is the mass of an atom. Although the SI unit of mass is the kilogram (symbol: kg), atomic mass is often expressed in the non-SI unit dalton (symbol: Da) – equivalently, unified atomic mass unit (u). 1&nbs ...

es that range from 104 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 Radioactive decay (also known as nuclear decay, radioactivity, radioactive disintegration, or nuclear disintegration) is the process by which an unstable atomic nucleus loses energy by radiation. A material containing unstable nuclei is consid ...

: ¹²⁸Te and ¹³⁰Te undergo

double beta decay In nuclear physics, double beta decay is a type of radioactive decay in which two neutrons are simultaneously transformed into two protons, or vice versa, inside an atomic nucleus. As in single beta decay, this process allows the atom to move clos ...

with

half-lives Half-life (symbol ) is the time required for a quantity (of substance) to reduce to half of its initial value. The term is commonly used in nuclear physics to describe how quickly unstable atoms undergo radioactive decay or how long stable at ...

of, respectively, 2.2×10²⁴ (2.2

septillion Two naming scales for large numbers have been used in English and other European languages since the early modern era: the long and short scales. Most English variants use the short scale today, but the long scale remains dominant in many non-Eng ...

) years (the longest half-life of all

nuclides A nuclide (or nucleide, from nucleus, also known as nuclear species) is a class of atoms characterized by their number of protons, ''Z'', their number of neutrons, ''N'', and their nuclear energy state. The word ''nuclide'' was coined by Truman ...

proven to be radioactive)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 and 8.2×10²⁰ (820

quintillion Two naming scales for large numbers have been used in English and other European languages since the early modern era: the long and short scales. Most English variants use the short scale today, but the long scale remains dominant in many non-Eng ...

) years. The longest-lived artificial radioisotope of tellurium is ¹²¹Te with a half-life of about 19 days. Several

s 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 Indium is a chemical element with the symbol In and atomic number 49. Indium is the softest metal that is not an alkali metal. It is a silvery-white metal that resembles tin in appearance. It is a post-transition metal that makes up 0.21 parts p ...

and

rhenium Rhenium is a chemical element with the symbol Re and atomic number 75. It is a silvery-gray, heavy, third-row transition metal in group 7 of the periodic table. With an estimated average concentration of 1 part per billion (ppb), rhenium is one ...

likewise have a radioisotope in greater abundance than a stable one. It has been claimed that

electron capture Electron capture (K-electron capture, also K-capture, or L-electron capture, L-capture) is a process in which the proton-rich nucleus of an electrically neutral atom absorbs an inner atomic electron, usually from the K or L electron shells. Thi ...

of ¹²³Te was observed, but the recent measurements of the same team have disproved this. The half-life of ¹²³Te is longer than 9.2 × 10¹⁶ years, and probably much longer. ¹²⁴Te can be used as a starting material in the production of

radionuclides A radionuclide (radioactive nuclide, radioisotope or radioactive isotope) is a nuclide that has excess nuclear energy, making it unstable. This excess energy can be used in one of three ways: emitted from the nucleus as gamma radiation; transfer ...

by a

cyclotron A cyclotron is a type of particle accelerator invented by Ernest O. Lawrence in 1929–1930 at the University of California, Berkeley, and patented in 1932. Lawrence, Ernest O. ''Method and apparatus for the acceleration of ions'', filed: Janu ...

or other particle accelerators. Some common radionuclides that can be produced from tellurium-124 are

iodine-123 Iodine-123 (123I) is a radioactive isotope of iodine used in nuclear medicine imaging, including single-photon emission computed tomography (SPECT) or SPECT/CT exams. The isotope's half-life is 13.2230 hours; the decay by electron capture to tellu ...

and

iodine-124 There are 37 known isotopes of iodine (53I) from 108I to 144I; all undergo radioactive decay except 127I, which is stable. Iodine is thus a monoisotopic element. Its longest-lived radioactive isotope, 129I, has a half-life of 15.7 million year ...

. The short-lived isotope ¹³⁵Te (half-life 19 seconds) is produced as a

fission product Nuclear fission products are the atomic fragments left after a large atomic nucleus undergoes nuclear fission. Typically, a large nucleus like that of uranium fissions by splitting into two smaller nuclei, along with a few neutrons, the release ...

in nuclear reactors. It decays, via two

beta decay In nuclear physics, beta decay (β-decay) is a type of radioactive decay in which a beta particle (fast energetic electron or positron) is emitted from an atomic nucleus, transforming the original nuclide to an isobar of that nuclide. For ...

s, to ¹³⁵Xe, the most powerful known

neutron absorber In applications such as nuclear reactors, a neutron poison (also called a neutron absorber or a nuclear poison) is a substance with a large neutron absorption cross-section. In such applications, absorbing neutrons is normally an undesirable eff ...

, and the cause of the

iodine pit The iodine pit, also called the iodine hole or xenon pit, is a temporary disabling of a nuclear reactor due to buildup of short- lived nuclear poisons in the reactor core. The main isotope responsible is 135Xe, mainly produced by natural decay of ...

phenomenon. With the exception of

beryllium Beryllium is a chemical element with the symbol Be and atomic number 4. It is a steel-gray, strong, lightweight and brittle alkaline earth metal. It is a divalent element that occurs naturally only in combination with other elements to form mi ...

, tellurium is the lightest element observed to commonly undergo

alpha decay Alpha decay or α-decay is a type of radioactive decay in which an atomic nucleus emits an alpha particle (helium nucleus) and thereby transforms or 'decays' into a different atomic nucleus, with a mass number that is reduced by four and an atom ...

, 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 A proton is a stable subatomic particle, symbol , H+, or 1H+ with a positive electric charge of +1 ''e'' elementary charge. Its mass is slightly less than that of a neutron and 1,836 times the mass of an electron (the proton–electron mass ...

beta emission In nuclear physics, beta decay (β-decay) is a type of radioactive decay in which a beta particle (fast energetic electron or positron) is emitted from an atomic nucleus, transforming the original nuclide to an isobar of that nuclide. For exam ...

) as a rare branch.

List of isotopes

, - , ¹⁰⁴Te , style="text-align:right" , 52 , style="text-align:right" , 52 , , <18 ns , α , ¹⁰⁰Sn , 0+ , , , - , ¹⁰⁵Te , style="text-align:right" , 52 , style="text-align:right" , 53 , 104.94364(54)# , 620(70) ns , α , ¹⁰¹Sn , 5/2+# , , , - , ¹⁰⁶Te , style="text-align:right" , 52 , style="text-align:right" , 54 , 105.93750(14) , 70(20) µs
0(+20−10) µs, α , ¹⁰²Sn , 0+ , , , - , rowspan=2, ¹⁰⁷Te , rowspan=2 style="text-align:right" , 52 , rowspan=2 style="text-align:right" , 55 , rowspan=2, 106.93501(32)# , rowspan=2, 3.1(1) ms , α (70%) , ¹⁰³Sn , rowspan=2, 5/2+# , rowspan=2, , rowspan=2, , - , β⁺ (30%) , ¹⁰⁷Sb , - , rowspan=4, ¹⁰⁸Te , rowspan=4 style="text-align:right" , 52 , rowspan=4 style="text-align:right" , 56 , rowspan=4, 107.92944(11) , rowspan=4, 2.1(1) s , α (49%) , ¹⁰⁴Sn , rowspan=4, 0+ , rowspan=4, , rowspan=4, , - , β⁺ (48.5%) , ¹⁰⁸Sb , - , β⁺, p (2.4%) , ¹⁰⁷Sn , - , β⁺, α (.065%) , ¹⁰⁴In , - , rowspan=4, ¹⁰⁹Te , rowspan=4 style="text-align:right" , 52 , rowspan=4 style="text-align:right" , 57 , rowspan=4, 108.92742(7) , rowspan=4, 4.6(3) s , β⁺ (86.99%) , ¹⁰⁹Sb , rowspan=4, (5/2+) , rowspan=4, , rowspan=4, , - , β⁺, p (9.4%) , ¹⁰⁸Sn , - , α (7.9%) , ¹⁰⁵Sn , - , β⁺, α (.005%) , ¹⁰⁵In , - , rowspan=2, ¹¹⁰Te , rowspan=2 style="text-align:right" , 52 , rowspan=2 style="text-align:right" , 58 , rowspan=2, 109.92241(6) , rowspan=2, 18.6(8) s , β⁺ (99.99%) , ¹¹⁰Sb , rowspan=2, 0+ , rowspan=2, , rowspan=2, , - , β⁺, p (.003%) , ¹⁰⁹Sn , - , rowspan=2, ¹¹¹Te , rowspan=2 style="text-align:right" , 52 , rowspan=2 style="text-align:right" , 59 , rowspan=2, 110.92111(8) , rowspan=2, 19.3(4) s , β⁺ , ¹¹¹Sb , rowspan=2, (5/2)+# , rowspan=2, , rowspan=2, , - , β⁺, p (rare) , ¹¹⁰Sn , - , ¹¹²Te , style="text-align:right" , 52 , style="text-align:right" , 60 , 111.91701(18) , 2.0(2) min , β⁺ , ¹¹²Sb , 0+ , , , - , ¹¹³Te , style="text-align:right" , 52 , style="text-align:right" , 61 , 112.91589(3) , 1.7(2) min , β⁺ , ¹¹³Sb , (7/2+) , , , - , ¹¹⁴Te , style="text-align:right" , 52 , style="text-align:right" , 62 , 113.91209(3) , 15.2(7) min , β⁺ , ¹¹⁴Sb , 0+ , , , - , ¹¹⁵Te , style="text-align:right" , 52 , style="text-align:right" , 63 , 114.91190(3) , 5.8(2) min , β⁺ , ¹¹⁵Sb , 7/2+ , , , - , rowspan=2 style="text-indent:1em" , ^115m1Te , rowspan=2 colspan="3" style="text-indent:2em" , 10(7) keV , rowspan=2, 6.7(4) min , β⁺ , ¹¹⁵Sb , rowspan=2, (1/2)+ , rowspan=2, , rowspan=2, , - , IT , ¹¹⁵Te , - , style="text-indent:1em" , ^115m2Te , colspan="3" style="text-indent:2em" , 280.05(20) keV , 7.5(2) µs , , , 11/2− , , , - , ¹¹⁶Te , style="text-align:right" , 52 , style="text-align:right" , 64 , 115.90846(3) , 2.49(4) h , β⁺ , ¹¹⁶Sb , 0+ , , , - , ¹¹⁷Te , style="text-align:right" , 52 , style="text-align:right" , 65 , 116.908645(14) , 62(2) min , β⁺ , ¹¹⁷Sb , 1/2+ , , , - , style="text-indent:1em" , ^117mTe , colspan="3" style="text-indent:2em" , 296.1(5) keV , 103(3) ms , IT , ¹¹⁷Te , (11/2−) , , , - , ¹¹⁸Te , style="text-align:right" , 52 , style="text-align:right" , 66 , 117.905828(16) , 6.00(2) d , EC , ¹¹⁸Sb , 0+ , , , - , ¹¹⁹Te , style="text-align:right" , 52 , style="text-align:right" , 67 , 118.906404(9) , 16.05(5) h , β⁺ , ¹¹⁹Sb , 1/2+ , , , - , rowspan=2 style="text-indent:1em" , ^119mTe , rowspan=2 colspan="3" style="text-indent:2em" , 260.96(5) keV , rowspan=2, 4.70(4) d , β⁺ (99.99%) , ¹¹⁹Sb , rowspan=2, 11/2− , rowspan=2, , rowspan=2, , - , IT (.008%) , ¹¹⁹Te , - , ¹²⁰Te , style="text-align:right" , 52 , style="text-align:right" , 68 , 119.90402(1) , colspan=3 align=center,

Observationally Stable Stable nuclides are nuclides that are not radioactive and so (unlike radionuclides) do not spontaneously undergo radioactive decay. When such nuclides are referred to in relation to specific elements, they are usually termed stable isotopes. Th ...

Believed to undergo β⁺β⁺ decay to ¹²⁰Sn with a half-life over 2.2×10¹⁶ years , 0+ , 9(1)×10⁻⁴ , , - , ¹²¹Te , style="text-align:right" , 52 , style="text-align:right" , 69 , 120.904936(28) , 19.16(5) d , β⁺ , ¹²¹Sb , 1/2+ , , , - , rowspan=2 style="text-indent:1em" , ^121mTe , rowspan=2 colspan="3" style="text-indent:2em" , 293.991(22) keV , rowspan=2, 154(7) d , IT (88.6%) , ¹²¹Te , rowspan=2, 11/2− , rowspan=2, , rowspan=2, , - , β⁺ (11.4%) , ¹²¹Sb , - , ¹²²Te , style="text-align:right" , 52 , style="text-align:right" , 70 , 121.9030439(16) , colspan=3 align=center, StableTheoretically capable of

spontaneous fission Spontaneous fission (SF) is a form of radioactive decay that is found only in very heavy chemical elements. The nuclear binding energy of the elements reaches its maximum at an atomic mass number of about 56 (e.g., iron-56); spontaneous breakdo ...

, 0+ , 0.0255(12) , , - , ¹²³Te , style="text-align:right" , 52 , style="text-align:right" , 71 , 122.9042700(16) , colspan=3 align=center, Observationally StableBelieved to undergo β⁺ decay to ¹²³Sb with a half-life over 9.2×10¹⁶ years , 1/2+ , 0.0089(3) , , - , style="text-indent:1em" , ^123mTe , colspan="3" style="text-indent:2em" , 247.47(4) keV , 119.2(1) d , IT , ¹²³Te , 11/2− , , , - , ¹²⁴Te , style="text-align:right" , 52 , style="text-align:right" , 72 , 123.9028179(16) , colspan=3 align=center, Stable , 0+ , 0.0474(14) , , - , ¹²⁵Te

Fission product Nuclear fission products are the atomic fragments left after a large atomic nucleus undergoes nuclear fission. Typically, a large nucleus like that of uranium fissions by splitting into two smaller nuclei, along with a few neutrons, the release ...

, style="text-align:right" , 52 , style="text-align:right" , 73 , 124.9044307(16) , colspan=3 align=center, Stable , 1/2+ , 0.0707(15) , , - , style="text-indent:1em" , ^125mTe , colspan="3" style="text-indent:2em" , 144.772(9) keV , 57.40(15) d , IT , ¹²⁵Te , 11/2− , , , - , ¹²⁶Te , style="text-align:right" , 52 , style="text-align:right" , 74 , 125.9033117(16) , colspan=3 align=center, Stable , 0+ , 0.1884(25) , , - , ¹²⁷Te , style="text-align:right" , 52 , style="text-align:right" , 75 , 126.9052263(16) , 9.35(7) h , β⁻ , ¹²⁷I , 3/2+ , , , - , rowspan=2 style="text-indent:1em" , ^127mTe , rowspan=2 colspan="3" style="text-indent:2em" , 88.26(8) keV , rowspan=2, 109(2) d , IT (97.6%) , ¹²⁷Te , rowspan=2, 11/2− , rowspan=2, , rowspan=2, , - , β⁻ (2.4%) , ¹²⁷I , - , ¹²⁸Te Primordial

radionuclide A radionuclide (radioactive nuclide, radioisotope or radioactive isotope) is a nuclide that has excess nuclear energy, making it unstable. This excess energy can be used in one of three ways: emitted from the nucleus as gamma radiation; transfer ...

, style="text-align:right" , 52 , style="text-align:right" , 76 , 127.9044631(19) , 2.2(3)×10²⁴ yLongest measured half-life of any nuclide , β⁻β⁻ , ¹²⁸Xe , 0+ , 0.3174(8) , , - , style="text-indent:1em" , ^128mTe , colspan="3" style="text-indent:2em" , 2790.7(4) keV , 370(30) ns , , , 10+ , , , - , ¹²⁹Te , style="text-align:right" , 52 , style="text-align:right" , 77 , 128.9065982(19) , 69.6(3) min , β⁻ , ¹²⁹I , 3/2+ , , , - , rowspan=2 style="text-indent:1em" , ^129mTe , rowspan=2 colspan="3" style="text-indent:2em" , 105.50(5) keV , rowspan=2 , 33.6(1) d , β⁻ (36%) , ¹²⁹I , rowspan=2 , 11/2− , rowspan=2 , , rowspan=2 , , - , IT (64%) , ¹²⁹Te , - , ¹³⁰Te , style="text-align:right" , 52 , style="text-align:right" , 78 , 129.9062244(21) , 8.2(0.2 (stat.), 0.6 (syst.)) y , β⁻β⁻ , ¹³⁰Xe , 0+ , 0.3408(62) , , - , style="text-indent:1em" , ^130m1Te , colspan="3" style="text-indent:2em" , 2146.41(4) keV , 115(8) ns , , , (7)− , , , - , style="text-indent:1em" , ^130m2Te , colspan="3" style="text-indent:2em" , 2661(7) keV , 1.90(8) µs , , , (10+) , , , - , style="text-indent:1em" , ^130m3Te , colspan="3" style="text-indent:2em" , 4375.4(18) keV , 261(33) ns , , , , , , - , ¹³¹Te , style="text-align:right" , 52 , style="text-align:right" , 79 , 130.9085239(21) , 25.0(1) min , β⁻ , ¹³¹I , 3/2+ , , , - , rowspan=2 style="text-indent:1em" , ^131mTe , rowspan=2 colspan="3" style="text-indent:2em" , 182.250(20) keV , rowspan=2, 30(2) h , β⁻ (77.8%) , ¹³¹I , rowspan=2, 11/2− , rowspan=2, , rowspan=2, , - , IT (22.2%) , ¹³¹Te , - , ¹³²Te , style="text-align:right" , 52 , style="text-align:right" , 80 , 131.908553(7) , 3.204(13) d , β⁻ , ¹³²I , 0+ , , , - , ¹³³Te , style="text-align:right" , 52 , style="text-align:right" , 81 , 132.910955(26) , 12.5(3) min , β⁻ , ¹³³I , (3/2+) , , , - , rowspan=2 style="text-indent:1em" , ^133mTe , rowspan=2 colspan="3" style="text-indent:2em" , 334.26(4) keV , rowspan=2, 55.4(4) min , β⁻ (82.5%) , ¹³³I , rowspan=2, (11/2−) , rowspan=2, , rowspan=2, , - , IT (17.5%) , ¹³³Te , - , ¹³⁴Te , style="text-align:right" , 52 , style="text-align:right" , 82 , 133.911369(11) , 41.8(8) min , β⁻ , ¹³⁴I , 0+ , , , - , style="text-indent:1em" , ^134mTe , colspan="3" style="text-indent:2em" , 1691.34(16) keV , 164.1(9) ns , , , 6+ , , , - , ¹³⁵TeVery short-lived

, responsible for the

as precursor of ¹³⁵Xe via ¹³⁵I , style="text-align:right" , 52 , style="text-align:right" , 83 , 134.91645(10) , 19.0(2) s , β⁻ , ¹³⁵I , (7/2−) , , , - , style="text-indent:1em" , ^135mTe , colspan="3" style="text-indent:2em" , 1554.88(17) keV , 510(20) ns , , , (19/2−) , , , - , rowspan=2, ¹³⁶Te , rowspan=2 style="text-align:right" , 52 , rowspan=2 style="text-align:right" , 84 , rowspan=2, 135.92010(5) , rowspan=2, 17.63(8) s , β⁻ (98.7%) , ¹³⁶I , rowspan=2, 0+ , rowspan=2, , rowspan=2, , - , β⁻, n (1.3%) , ¹³⁵I , - , rowspan=2, ¹³⁷Te , rowspan=2 style="text-align:right" , 52 , rowspan=2 style="text-align:right" , 85 , rowspan=2, 136.92532(13) , rowspan=2, 2.49(5) s , β⁻ (97.01%) , ¹³⁷I , rowspan=2, 3/2−# , rowspan=2, , rowspan=2, , - , β⁻, n (2.99%) , ¹³⁶I , - , rowspan=2, ¹³⁸Te , rowspan=2 style="text-align:right" , 52 , rowspan=2 style="text-align:right" , 86 , rowspan=2, 137.92922(22)# , rowspan=2, 1.4(4) s , β⁻ (93.7%) , ¹³⁸I , rowspan=2, 0+ , rowspan=2, , rowspan=2, , - , β⁻, n (6.3%) , ¹³⁷I , - , rowspan=2, ¹³⁹Te , rowspan=2 style="text-align:right" , 52 , rowspan=2 style="text-align:right" , 87 , rowspan=2, 138.93473(43)# , rowspan=2, 500 ms
300 ns , β⁻ , ¹³⁹I , rowspan=2, 5/2−# , rowspan=2, , rowspan=2, , - , β⁻, n , ¹³⁸I , - , rowspan=2, ¹⁴⁰Te , rowspan=2 style="text-align:right" , 52 , rowspan=2 style="text-align:right" , 88 , rowspan=2, 139.93885(32)# , rowspan=2, 300 ms
300 ns , β⁻ , ¹⁴⁰I , rowspan=2, 0+ , rowspan=2, , rowspan=2, , - , β⁻, n , ¹³⁹I , - , rowspan=2, ¹⁴¹Te , rowspan=2 style="text-align:right" , 52 , rowspan=2 style="text-align:right" , 89 , rowspan=2, 140.94465(43)# , rowspan=2, 100 ms
300 ns , β⁻ , ¹⁴¹I , rowspan=2, 5/2−# , rowspan=2, , rowspan=2, , - , β⁻, n , ¹⁴⁰I , - , ¹⁴²Te , style="text-align:right" , 52 , style="text-align:right" , 90 , 141.94908(64)# , 50 ms
300 ns , β⁻ , ¹⁴²I , 0+ , ,

References

* Isotope masses from: ** * Isotopic compositions and standard atomic masses from: ** ** * Half-life, spin, and isomer data selected from the following sources. ** ** ** ** {{Navbox element isotopes Tellurium

Tellurium Tellurium is a chemical element with the symbol Te and atomic number 52. It is a brittle, mildly toxic, rare, silver-white metalloid. Tellurium is chemically related to selenium and sulfur, all three of which are chalcogens. It is occasionally fou ...