Technetium (₄₃Tc) is one of the two elements with that have no stable isotopes; the other such element is

promethium Promethium is a chemical element with the symbol Pm and atomic number 61. All of its isotopes are radioactive; it is extremely rare, with only about 500–600 grams naturally occurring in Earth's crust at any given time. Promethium is one of onl ...

. – Elements marked with a * have no stable isotope: 43, 61, and 83 and up. It is primarily artificial, with only trace quantities existing in nature produced by

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 ...

(there are an estimated grams of ⁹⁹Tc per gram of pitchblende) or neutron capture by

molybdenum Molybdenum is a chemical element with the symbol Mo and atomic number 42 which is located in period 5 and group 6. The name is from Neo-Latin ''molybdaenum'', which is based on Ancient Greek ', meaning lead, since its ores were confused with lea ...

. The first isotopes to be synthesized were ⁹⁷Tc and ⁹⁹Tc in 1936, the first artificial element to be produced. The most stable radioisotopes are ⁹⁷Tc ( half-life of 4.21 million years), ⁹⁸Tc (half-life: 4.2 million years), and ⁹⁹Tc (half-life: 211,100 years). Thirty-three other radioisotopes have been characterized with atomic masses ranging from ⁸⁵Tc to ¹²⁰Tc. Most of these have half-lives that are less than an hour; the exceptions are ⁹³Tc (half-life: 2.75 hours), ⁹⁴Tc (half-life: 4.883 hours), ⁹⁵Tc (half-life: 20 hours), and ⁹⁶Tc (half-life: 4.28 days). Technetium also has numerous meta states. ^97mTc is the most stable, with a half-life of 91.0 days (0.097 MeV). This is followed by ^95mTc (half-life: 61 days, 0.038 MeV) and ^99mTc (half-life: 6.04 hours, 0.143 MeV). ^99mTc only emits gamma rays, subsequently decaying to ⁹⁹Tc. For isotopes lighter than ⁹⁸Tc, the primary

decay mode 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 ...

is electron capture to

isotopes of molybdenum Molybdenum (42Mo) has 33 known isotopes, ranging in atomic mass from 83 to 115, as well as four metastable nuclear isomers. Seven isotopes occur naturally, with atomic masses of 92, 94, 95, 96, 97, 98, and 100. All unstable isotopes of molybdenu ...

. For the heavier isotopes, the primary mode is beta emission to isotopes of ruthenium, with the exception that ¹⁰⁰Tc can decay both by beta emission and electron capture. Technetium-99m is the hallmark technetium isotope employed in the nuclear medicine industry. Its low-energy

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

, which yields a gamma-ray at ~140.5 keV, is ideal for imaging using Single Photon Emission Computed Tomography (SPECT). Several technetium isotopes, such as ^94mTc, ^95gTc, and ^96gTc, which are produced via (p,n) reactions using a cyclotron on

targets, have also been identified as potential Positron Emission Tomography (PET) agents. Technetium-101 has been produced using a

D-D fusion Fusion power is a proposed form of power generation that would generate electricity by using heat from nuclear fusion reactions. In a fusion process, two lighter atomic nuclei combine to form a heavier nucleus, while releasing energy. Devices de ...

-based neutron generator from the ¹⁰⁰Mo(n,γ)¹⁰¹Mo reaction on natural molybdenum and subsequent beta-minus decay of ¹⁰¹Mo to ¹⁰¹Tc. Despite its shorter-half life (i.e., 14.22 min), ¹⁰¹Tc exhibits unique decay characteristics suitable for radioisotope diagnostic or therapeutic procedures, where it has been proposed that its implementation, as a supplement for dual-isotopic imaging or replacement for ^99mTc, could be performed by on-site production and dispensing at the point of patient care. Technetium-99 is the most common and most readily available isotope, as it is a major

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 ...

from fission of actinides like uranium and plutonium with a fission product yield of 6% or more, and in fact the most significant

long-lived fission product Long-lived fission products (LLFPs) are radioactive materials with a long half-life (more than 200,000 years) produced by nuclear fission of uranium and plutonium. Because of their persistent radiotoxicity it is necessary to isolate them from man ...

. Lighter isotopes of technetium are almost never produced in fission because the initial fission products normally have a higher neutron/proton ratio than is stable for their mass range, and therefore undergo beta decay until reaching the ultimate product. Beta decay of fission products of mass 95–98 stops at the stable

of those masses and does not reach technetium. For mass 100 and greater, the technetium isotopes of those masses are very short-lived and quickly beta decay to isotopes of ruthenium. Therefore, the technetium in spent nuclear fuel is practically all ⁹⁹Tc. In the presence of fast neutrons a small amount of will be produced by (n,2n) "knockout" reactions. If

nuclear transmutation Nuclear transmutation is the conversion of one chemical element or an isotope into another chemical element. Nuclear transmutation occurs in any process where the number of protons or neutrons in the nucleus of an atom is changed. A transmutatio ...

of fission-derived Technetium or Technetium waste from medical applications is desired, fast neutrons are therefore not desirable as the long lived increases rather than reducing the longevity of the radioactivity in the material. One gram of ⁹⁹Tc produces disintegrations a second (that is, 0.62 G Bq/g). Technetium has no stable or nearly stable isotopes, and thus a

standard atomic weight The standard atomic weight of a chemical element (symbol ''A''r°(E) for element "E") is the weighted arithmetic mean of the relative isotopic masses of all isotopes of that element weighted by each isotope's abundance on Earth. For example, is ...

cannot be given.

List of isotopes

, - , rowspan=3, ⁸⁵Tc , rowspan=3 style="text-align:right" , 43 , rowspan=3 style="text-align:right" , 42 , rowspan=3, 84.94883(43)# , rowspan=3, <110 ns , β⁺ , ⁸⁵Mo , rowspan=3, 1/2−# , rowspan=3 , , - , p , ⁸⁴Mo , - , β⁺, p , ⁸⁴Nb , - , ⁸⁶Tc , style="text-align:right" , 43 , style="text-align:right" , 43 , 85.94288(32)# , 55(6) ms , β⁺ , ⁸⁶Mo , (0+) , , - , style="text-indent:1em" , ^86mTc , colspan="3" style="text-indent:2em" , 1500(150) keV , 1.11(21) µs , , , (5+, 5−) , , - , ⁸⁷Tc , style="text-align:right" , 43 , style="text-align:right" , 44 , 86.93653(32)# , 2.18(16) s , β⁺ , ⁸⁷Mo , 1/2−# , , - , style="text-indent:1em" , ^87mTc , colspan="3" style="text-indent:2em" , 20(60)# keV , 2# s , , , 9/2+# , , - , ⁸⁸Tc , style="text-align:right" , 43 , style="text-align:right" , 45 , 87.93268(22)# , 5.8(2) s , β⁺ , ⁸⁸Mo , (2, 3) , , - , style="text-indent:1em" , ^88mTc , colspan="3" style="text-indent:2em" , 0(300)# keV , 6.4(8) s , β⁺ , ⁸⁸Mo , (6, 7, 8) , , - , ⁸⁹Tc , style="text-align:right" , 43 , style="text-align:right" , 46 , 88.92717(22)# , 12.8(9) s , β⁺ , ⁸⁹Mo , (9/2+) , , - , style="text-indent:1em" , ^89mTc , colspan="3" style="text-indent:2em" , 62.6(5) keV , 12.9(8) s , β⁺ , ⁸⁹Mo , (1/2−) , , - , ⁹⁰Tc , style="text-align:right" , 43 , style="text-align:right" , 47 , 89.92356(26) , 8.7(2) s , β⁺ , ⁹⁰Mo , 1+ , , - , style="text-indent:1em" , ^90mTc , colspan="3" style="text-indent:2em" , 310(390) keV , 49.2(4) s , β⁺ , ⁹⁰Mo , (8+) , , - , ⁹¹Tc , style="text-align:right" , 43 , style="text-align:right" , 48 , 90.91843(22) , 3.14(2) min , β⁺ , ⁹¹Mo , (9/2)+ , , - , rowspan=2 style="text-indent:1em" , ^91mTc , rowspan=2 colspan="3" style="text-indent:2em" , 139.3(3) keV , rowspan=2, 3.3(1) min , β⁺ (99%) , ⁹¹Mo , rowspan=2, (1/2)− , rowspan=2, , - , IT (1%) , ⁹¹Tc , - , ⁹²Tc , style="text-align:right" , 43 , style="text-align:right" , 49 , 91.915260(28) , 4.25(15) min , β⁺ , ⁹²Mo , (8)+ , , - , style="text-indent:1em" , ^92mTc , colspan="3" style="text-indent:2em" , 270.15(11) keV , 1.03(7) µs , , , (4+) , , - , ⁹³Tc , style="text-align:right" , 43 , style="text-align:right" , 50 , 92.910249(4) , 2.75(5) h , β⁺ , ⁹³Mo , 9/2+ , , - , rowspan=2 style="text-indent:1em" , ^93m1Tc , rowspan=2 colspan="3" style="text-indent:2em" , 391.84(8) keV , rowspan=2, 43.5(10) min , IT (76.6%) , ⁹³Tc , rowspan=2, 1/2− , rowspan=2, , - , β⁺ (23.4%) , ⁹³Mo , - , style="text-indent:1em" , ^93m2Tc , colspan="3" style="text-indent:2em" , 2185.16(15) keV , 10.2(3) µs , , , (17/2)− , , - , ⁹⁴Tc , style="text-align:right" , 43 , style="text-align:right" , 51 , 93.909657(5) , 293(1) min , β⁺ , ⁹⁴Mo , 7+ , , - , rowspan=2 style="text-indent:1em" , ^94mTc , rowspan=2 colspan="3" style="text-indent:2em" , 75.5(19) keV , rowspan=2, 52.0(10) min , β⁺ (99.9%) , ⁹⁴Mo , rowspan=2, (2)+ , rowspan=2, , - , IT (.1%) , ⁹⁴Tc , - , ⁹⁵Tc , style="text-align:right" , 43 , style="text-align:right" , 52 , 94.907657(6) , 20.0(1) h , β⁺ , ⁹⁵Mo , 9/2+ , , - , rowspan=2 style="text-indent:1em" , ^95mTc , rowspan=2 colspan="3" style="text-indent:2em" , 38.89(5) keV , rowspan=2, 61(2) d , β⁺ (96.12%) , ⁹⁵Mo , rowspan=2, 1/2− , rowspan=2, , - , IT (3.88%) , ⁹⁵Tc , - , ⁹⁶Tc , style="text-align:right" , 43 , style="text-align:right" , 53 , 95.907871(6) , 4.28(7) d , β⁺ , ⁹⁶Mo , 7+ , , - , rowspan=2 style="text-indent:1em" , ^96mTc , rowspan=2 colspan="3" style="text-indent:2em" , 34.28(7) keV , rowspan=2, 51.5(10) min , IT (98%) , ⁹⁶Tc , rowspan=2, 4+ , rowspan=2, , - , β⁺ (2%) , ⁹⁶Mo , - , ⁹⁷Tc , style="text-align:right" , 43 , style="text-align:right" , 54 , 96.906365(5) , 4.21×10⁶ y , EC , ⁹⁷Mo , 9/2+ , , - , rowspan=2 style="text-indent:1em" , ^97mTc , rowspan=2 colspan="3" style="text-indent:2em" , 96.56(6) keV , rowspan=2, 91.0(6) d , IT (99.66%) , ⁹⁷Tc , rowspan=2, 1/2− , rowspan=2, , - , EC (.34%) , ⁹⁷Mo , - , ⁹⁸Tc , style="text-align:right" , 43 , style="text-align:right" , 55 , 97.907216(4) , 4.2×10⁶ y , β⁻ , ⁹⁸Ru , (6)+ , , - , style="text-indent:1em" , ^98mTc , colspan="3" style="text-indent:2em" , 90.76(16) keV , 14.7(3) µs , , , (2)− , , - , ⁹⁹Tc

Long-lived fission product Long-lived fission products (LLFPs) are radioactive materials with a long half-life (more than 200,000 years) produced by nuclear fission of uranium and plutonium. Because of their persistent radiotoxicity it is necessary to isolate them from man ...

, style="text-align:right" , 43 , style="text-align:right" , 56 , 98.9062547(21) , 2.111(12)×10⁵ y , β⁻ , ⁹⁹Ru , 9/2+ , trace , - , rowspan=2 style="text-indent:1em" , ^99mTcUsed in medicine , rowspan=2 colspan="3" style="text-indent:2em" , 142.6832(11) keV , rowspan=2, 6.0067(5) h , IT (99.99%) , ⁹⁹Tc , rowspan=2, 1/2− , rowspan=2, , - , β⁻ (.0037%) , ⁹⁹Ru , - , rowspan=2, ¹⁰⁰Tc , rowspan=2 style="text-align:right" , 43 , rowspan=2 style="text-align:right" , 57 , rowspan=2, 99.9076578(24) , rowspan=2, 15.8(1) s , β⁻ (99.99%) , ¹⁰⁰Ru , rowspan=2, 1+ , rowspan=2, , - , EC (.0018%) , ''¹⁰⁰Mo'' , - , style="text-indent:1em" , ^100m1Tc , colspan="3" style="text-indent:2em" , 200.67(4) keV , 8.32(14) µs , , , (4)+ , , - , style="text-indent:1em" , ^100m2Tc , colspan="3" style="text-indent:2em" , 243.96(4) keV , 3.2(2) µs , , , (6)+ , , - , ¹⁰¹Tc , style="text-align:right" , 43 , style="text-align:right" , 58 , 100.907315(26) , 14.22(1) min , β⁻ , ¹⁰¹Ru , 9/2+ , , - , style="text-indent:1em" , ^101mTc , colspan="3" style="text-indent:2em" , 207.53(4) keV , 636(8) µs , , , 1/2− , , - , ¹⁰²Tc , style="text-align:right" , 43 , style="text-align:right" , 59 , 101.909215(10) , 5.28(15) s , β⁻ , ¹⁰²Ru , 1+ , , - , rowspan=2 style="text-indent:1em" , ^102mTc , rowspan=2 colspan="3" style="text-indent:2em" , 20(10) keV , rowspan=2, 4.35(7) min , β⁻ (98%) , ¹⁰²Ru , rowspan=2, (4, 5) , rowspan=2, , - , IT (2%) , ¹⁰²Tc , - , ¹⁰³Tc , style="text-align:right" , 43 , style="text-align:right" , 60 , 102.909181(11) , 54.2(8) s , β⁻ , ¹⁰³Ru , 5/2+ , , - , ¹⁰⁴Tc , style="text-align:right" , 43 , style="text-align:right" , 61 , 103.91145(5) , 18.3(3) min , β⁻ , ¹⁰⁴Ru , (3+)# , , - , style="text-indent:1em" , ^104m1Tc , colspan="3" style="text-indent:2em" , 69.7(2) keV , 3.5(3) µs , , , 2(+) , , - , style="text-indent:1em" , ^104m2Tc , colspan="3" style="text-indent:2em" , 106.1(3) keV , 0.40(2) µs , , , (+) , , - , ¹⁰⁵Tc , style="text-align:right" , 43 , style="text-align:right" , 62 , 104.91166(6) , 7.6(1) min , β⁻ , ¹⁰⁵Ru , (3/2−) , , - , ¹⁰⁶Tc , style="text-align:right" , 43 , style="text-align:right" , 63 , 105.914358(14) , 35.6(6) s , β⁻ , ¹⁰⁶Ru , (1, 2) , , - , ¹⁰⁷Tc , style="text-align:right" , 43 , style="text-align:right" , 64 , 106.91508(16) , 21.2(2) s , β⁻ , ¹⁰⁷Ru , (3/2−) , , - , style="text-indent:1em" , ^107mTc , colspan="3" style="text-indent:2em" , 65.7(10) keV , 184(3) ns , , , (5/2−) , , - , ¹⁰⁸Tc , style="text-align:right" , 43 , style="text-align:right" , 65 , 107.91846(14) , 5.17(7) s , β⁻ , ¹⁰⁸Ru , (2)+ , , - , rowspan=2, ¹⁰⁹Tc , rowspan=2 style="text-align:right" , 43 , rowspan=2 style="text-align:right" , 66 , rowspan=2, 108.91998(10) , rowspan=2, 860(40) ms , β⁻ (99.92%) , ¹⁰⁹Ru , rowspan=2, 3/2−# , rowspan=2, , - , β⁻, n (.08%) , ¹⁰⁸Ru , - , rowspan=2, ¹¹⁰Tc , rowspan=2 style="text-align:right" , 43 , rowspan=2 style="text-align:right" , 67 , rowspan=2, 109.92382(8) , rowspan=2, 0.92(3) s , β⁻ (99.96%) , ¹¹⁰Ru , rowspan=2, (2+) , rowspan=2, , - , β⁻, n (.04%) , ¹⁰⁹Ru , - , rowspan=2, ¹¹¹Tc , rowspan=2 style="text-align:right" , 43 , rowspan=2 style="text-align:right" , 68 , rowspan=2, 110.92569(12) , rowspan=2, 290(20) ms , β⁻ (99.15%) , ¹¹¹Ru , rowspan=2, 3/2−# , rowspan=2, , - , β⁻, n (.85%) , ¹¹⁰Ru , - , rowspan=2, ¹¹²Tc , rowspan=2 style="text-align:right" , 43 , rowspan=2 style="text-align:right" , 69 , rowspan=2, 111.92915(13) , rowspan=2, 290(20) ms , β⁻ (97.4%) , ¹¹²Ru , rowspan=2, 2+# , rowspan=2, , - , β⁻, n (2.6%) , ¹¹¹Ru , - , ¹¹³Tc , style="text-align:right" , 43 , style="text-align:right" , 70 , 112.93159(32)# , 170(20) ms , β⁻ , ¹¹³Ru , 3/2−# , , - , ¹¹⁴Tc , style="text-align:right" , 43 , style="text-align:right" , 71 , 113.93588(64)# , 150(30) ms , β⁻ , ¹¹⁴Ru , 2+# , , - , ¹¹⁵Tc , style="text-align:right" , 43 , style="text-align:right" , 72 , 114.93869(75)# , 100# ms 300 ns, β⁻ , ¹¹⁵Ru , 3/2−# , , - , ¹¹⁶Tc , style="text-align:right" , 43 , style="text-align:right" , 73 , 115.94337(75)# , 90# ms 300 ns, , , 2+# , , - , ¹¹⁷Tc , style="text-align:right" , 43 , style="text-align:right" , 74 , 116.94648(75)# , 40# ms 300 ns, , , 3/2−# , , - , ¹¹⁸Tc , style="text-align:right" , 43 , style="text-align:right" , 75 , 117.95148(97)# , 30# ms 300 ns, , , 2+# ,

Stability of technetium isotopes

Technetium and

are unusual light elements in that they have no stable isotopes. Using the liquid drop model for atomic nuclei, one can derive a semiempirical formula for the binding energy of a nucleus. This formula predicts a " valley of beta stability" along which

nuclide 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 ...

s do not undergo beta decay. Nuclides that lie "up the walls" of the valley tend to decay by beta decay towards the center (by emitting an electron, emitting a

positron The positron or antielectron is the antiparticle or the antimatter counterpart of the electron. It has an electric charge of +1 '' e'', a spin of 1/2 (the same as the electron), and the same mass as an electron. When a positron collides ...

, or capturing an electron). For a fixed number of nucleons ''A'', the binding energies lie on one or more parabolas, with the most stable nuclide at the bottom. One can have more than one parabola because isotopes with an even number of protons and an even number of neutrons are more stable than isotopes with an odd number of neutrons and an odd number of protons. A single beta decay then transforms one into the other. When there is only one parabola, there can be only one stable isotope lying on that parabola. When there are two parabolas, that is, when the number of nucleons is even, it can happen (rarely) that there is a stable nucleus with an odd number of neutrons and an odd number of protons (although this happens only in four instances: ²H, ⁶Li, ¹⁰B, and ¹⁴N). However, if this happens, there can be no stable isotope with an even number of neutrons and an even number of protons. (see Beta-decay stable isobars) For technetium (''Z'' = 43), the valley of beta stability is centered at around 98 nucleons. However, for every number of nucleons from 94 to 102, there is already at least one stable nuclide of either

(''Z'' = 42) or ruthenium (''Z'' = 44), and the

Mattauch isobar rule The Mattauch isobar rule, formulated by Josef Mattauch in 1934, states that if two adjacent chemical element, elements on the periodic table have isotopes of the same mass number, one of these isotopes must be radioactivity, radioactive. Two nuclide ...

states that two adjacent isobars cannot both be stable. For the isotopes with odd numbers of nucleons, this immediately rules out a stable isotope of technetium, since there can be only one stable nuclide with a fixed odd number of nucleons. For the isotopes with an even number of nucleons, since technetium has an odd number of protons, any isotope must also have an odd number of neutrons. In such a case, the presence of a stable nuclide having the same number of nucleons and an even number of protons rules out the possibility of a stable nucleus.''Radiochemistry and Nuclear Chemistry''

References

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