Molybdenum (₄₂Mo) has 33 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 numb ...

s, ranging in

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&nb ...

from 83 to 115, as well as four metastable

nuclear isomer 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 ...

s. Seven isotopes occur naturally, with atomic masses of 92, 94, 95, 96, 97, 98, and 100. All unstable isotopes of molybdenum decay into isotopes of

zirconium Zirconium is a chemical element with the symbol Zr and atomic number 40. The name ''zirconium'' is taken from the name of the mineral zircon, the most important source of zirconium. The word is related to Persian '' zargun'' (zircon; ''zar-gun'' ...

, niobium,

technetium Technetium is a chemical element with the symbol Tc and atomic number 43. It is the lightest element whose isotopes are all radioactive. All available technetium is produced as a synthetic element. Naturally occurring technetium is a spontaneous ...

, and

ruthenium Ruthenium is a chemical element with the symbol Ru and atomic number 44. It is a rare transition metal belonging to the platinum group of the periodic table. Like the other metals of the platinum group, ruthenium is inert to most other chemical ...

. Molybdenum-100 is the only naturally occurring isotope that is not stable. Molybdenum-100 has a

half-life 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 approximately 1×10¹⁹ y and undergoes

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 ...

into

-100. Molybdenum-98 is the most common isotope, comprising 24.14% of all molybdenum on Earth. Molybdenum isotopes with mass numbers 111 and up all have half-lives of approximately .15 s.

List of isotopes

, - , rowspan=2, ⁸³Mo , rowspan=2 style="text-align:right" , 42 , rowspan=2 style="text-align:right" , 41 , rowspan=2, 82.94874(54)# , rowspan=2, 23(19) ms
(+30-3) ms, β⁺ , ⁸³Nb , rowspan=2, 3/2−# , rowspan=2, , rowspan=2, , - , β⁺, p , ⁸²Zr , - , ⁸⁴Mo , style="text-align:right" , 42 , style="text-align:right" , 42 , 83.94009(43)# , 3.8(9) ms
.7(+10-8) s, β⁺ , ⁸⁴Nb , 0+ , , , - , ⁸⁵Mo , style="text-align:right" , 42 , style="text-align:right" , 43 , 84.93655(30)# , 3.2(2) s , β⁺ , ⁸⁵Nb , (1/2−)# , , , - , ⁸⁶Mo , style="text-align:right" , 42 , style="text-align:right" , 44 , 85.93070(47) , 19.6(11) s , β⁺ , ⁸⁶Nb , 0+ , , , - , rowspan=2, ⁸⁷Mo , rowspan=2 style="text-align:right" , 42 , rowspan=2 style="text-align:right" , 45 , rowspan=2, 86.92733(24) , rowspan=2, 14.05(23) s , β⁺ (85%) , ⁸⁷Nb , rowspan=2, 7/2+# , rowspan=2, , rowspan=2, , - , β⁺, p (15%) , ⁸⁶Zr , - , ⁸⁸Mo , style="text-align:right" , 42 , style="text-align:right" , 46 , 87.921953(22) , 8.0(2) min , β⁺ , ⁸⁸Nb , 0+ , , , - , ⁸⁹Mo , style="text-align:right" , 42 , style="text-align:right" , 47 , 88.919480(17) , 2.11(10) min , β⁺ , ⁸⁹Nb , (9/2+) , , , - , style="text-indent:1em" , ^89mMo , colspan="3" style="text-indent:2em" , 387.5(2) keV , 190(15) ms , IT , ⁸⁹Mo , (1/2−) , , , - , ⁹⁰Mo , style="text-align:right" , 42 , style="text-align:right" , 48 , 89.913937(7) , 5.56(9) h , β⁺ , ⁹⁰Nb , 0+ , , , - , style="text-indent:1em" , ^90mMo , colspan="3" style="text-indent:2em" , 2874.73(15) keV , 1.12(5) μs , , , 8+# , , , - , ⁹¹Mo , style="text-align:right" , 42 , style="text-align:right" , 49 , 90.911750(12) , 15.49(1) min , β⁺ , ⁹¹Nb , 9/2+ , , , - , rowspan=2 style="text-indent:1em" , ^91mMo , rowspan=2 colspan="3" style="text-indent:2em" , 653.01(9) keV , rowspan=2, 64.6(6) s , IT (50.1%) , ⁹¹Mo , rowspan=2, 1/2− , rowspan=2, , rowspan=2, , - , β⁺ (49.9%) , ⁹¹Nb , - , ⁹²Mo , style="text-align:right" , 42 , style="text-align:right" , 50 , 91.906811(4) , 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 decay by β⁺β⁺ to ⁹²Zr with a half-life over 1.9×10²⁰ years , 0+ , 0.14649(106) , , - , style="text-indent:1em" , ^92mMo , colspan="3" style="text-indent:2em" , 2760.46(16) keV , 190(3) ns , , , 8+ , , , - , ⁹³Mo , style="text-align:right" , 42 , style="text-align:right" , 51 , 92.906813(4) , 4,000(800) y , EC , ⁹³Nb , 5/2+ , , , - , rowspan=2 style="text-indent:1em" , ^93mMo , rowspan=2 colspan="3" style="text-indent:2em" , 2424.89(3) keV , rowspan=2, 6.85(7) h , IT (99.88%) , ⁹³Mo , rowspan=2, 21/2+ , rowspan=2, , rowspan=2, , - , β⁺ (.12%) , ⁹³Nb , - , ⁹⁴Mo , style="text-align:right" , 42 , style="text-align:right" , 52 , 93.9050883(21) , colspan=3 align=center, StableTheoretically capable of spontaneous fission , 0+ , 0.09187(33) , , - , ⁹⁵Mo Fission product , style="text-align:right" , 42 , style="text-align:right" , 53 , 94.9058421(21) , colspan=3 align=center, Stable , 5/2+ , 0.15873(30) , , - , ⁹⁶Mo , style="text-align:right" , 42 , style="text-align:right" , 54 , 95.9046795(21) , colspan=3 align=center, Stable , 0+ , 0.16673(30) , , - , ⁹⁷Mo , style="text-align:right" , 42 , style="text-align:right" , 55 , 96.9060215(21) , colspan=3 align=center, Stable , 5/2+ , 0.09582(15) , , - , ⁹⁸Mo , style="text-align:right" , 42 , style="text-align:right" , 56 , 97.90540482(21) , colspan=3 align=center, Observationally StableBelieved to decay by β⁻β⁻ to ⁹⁸Ru with a half-life of over 1×10¹⁴ years , 0+ , 0.24292(80) , , - , ⁹⁹MoUsed to produce the medically useful radioisotope

technetium-99m Technetium-99m (99mTc) is a metastable nuclear isomer of technetium-99 (itself an isotope of technetium), symbolized as 99mTc, that is used in tens of millions of medical diagnostic procedures annually, making it the most commonly used medical ra ...

, style="text-align:right" , 42 , style="text-align:right" , 57 , 98.9077119(21) , 2.7489(6) d , β⁻ , ^99mTc , 1/2+ , , , - , style="text-indent:1em" , ^99m1Mo , colspan="3" style="text-indent:2em" , 97.785(3) keV , 15.5(2) μs , , , 5/2+ , , , - , style="text-indent:1em" , ^99m2Mo , colspan="3" style="text-indent:2em" , 684.5(4) keV , 0.76(6) μs , , , 11/2− , , , - , ¹⁰⁰Mo Primordial radionuclide , style="text-align:right" , 42 , style="text-align:right" , 58 , 99.907477(6) , 8.5(5)×10¹⁸ a , β⁻β⁻ , ¹⁰⁰Ru , 0+ , 0.09744(65) , , - , ¹⁰¹Mo , style="text-align:right" , 42 , style="text-align:right" , 59 , 100.910347(6) , 14.61(3) min , β⁻ , ¹⁰¹Tc , 1/2+ , , , - , ¹⁰²Mo , style="text-align:right" , 42 , style="text-align:right" , 60 , 101.910297(22) , 11.3(2) min , β⁻ , ¹⁰²Tc , 0+ , , , - , ¹⁰³Mo , style="text-align:right" , 42 , style="text-align:right" , 61 , 102.91321(7) , 67.5(15) s , β⁻ , ¹⁰³Tc , (3/2+) , , , - , ¹⁰⁴Mo , style="text-align:right" , 42 , style="text-align:right" , 62 , 103.91376(6) , 60(2) s , β⁻ , ¹⁰⁴Tc , 0+ , , , - , ¹⁰⁵Mo , style="text-align:right" , 42 , style="text-align:right" , 63 , 104.91697(8) , 35.6(16) s , β⁻ , ¹⁰⁵Tc , (5/2−) , , , - , ¹⁰⁶Mo , style="text-align:right" , 42 , style="text-align:right" , 64 , 105.918137(19) , 8.73(12) s , β⁻ , ¹⁰⁶Tc , 0+ , , , - , ¹⁰⁷Mo , style="text-align:right" , 42 , style="text-align:right" , 65 , 106.92169(17) , 3.5(5) s , β⁻ , ¹⁰⁷Tc , (7/2−) , , , - , style="text-indent:1em" , ^107mMo , colspan="3" style="text-indent:2em" , 66.3(2) keV , 470(30) ns , , , (5/2−) , , , - , ¹⁰⁸Mo , style="text-align:right" , 42 , style="text-align:right" , 66 , 107.92345(21)# , 1.09(2) s , β⁻ , ¹⁰⁸Tc , 0+ , , , - , ¹⁰⁹Mo , style="text-align:right" , 42 , style="text-align:right" , 67 , 108.92781(32)# , 0.53(6) s , β⁻ , ¹⁰⁹Tc , (7/2−)# , , , - , rowspan=2, ¹¹⁰Mo , rowspan=2 style="text-align:right" , 42 , rowspan=2 style="text-align:right" , 68 , rowspan=2, 109.92973(43)# , rowspan=2, 0.27(1) s , β⁻ (>99.9%) , ¹¹⁰Tc , rowspan=2, 0+ , rowspan=2, , rowspan=2, , - , β⁻, n (<.1%) , ¹⁰⁹Tc , - , ¹¹¹Mo , style="text-align:right" , 42 , style="text-align:right" , 69 , 110.93441(43)# , 200# ms
300 ns, β⁻ , ¹¹¹Tc , , , , - , ¹¹²Mo , style="text-align:right" , 42 , style="text-align:right" , 70 , 111.93684(64)# , 150# ms
300 ns, β⁻ , ¹¹²Tc , 0+ , , , - , ¹¹³Mo , style="text-align:right" , 42 , style="text-align:right" , 71 , 112.94188(64)# , 100# ms
300 ns, β⁻ , ¹¹³Tc , , , , - , ¹¹⁴Mo , style="text-align:right" , 42 , style="text-align:right" , 72 , 113.94492(75)# , 80# ms
300 ns, , , 0+ , , , - , ¹¹⁵Mo , style="text-align:right" , 42 , style="text-align:right" , 73 , 114.95029(86)# , 60# ms
300 ns, , , , ,

Molybdenum-99

Molybdenum-99 is produced commercially by intense neutron-bombardment of a highly purified

uranium-235 Uranium-235 (235U or U-235) is an isotope of uranium making up about 0.72% of natural uranium. Unlike the predominant isotope uranium-238, it is fissile, i.e., it can sustain a nuclear chain reaction. It is the only fissile isotope that exi ...

target, followed rapidly by extraction. It is used as a parent radioisotope in

technetium-99m generator A technetium-99m generator, or colloquially a technetium cow or moly cow, is a device used to extract the metastable isotope 99mTc of technetium from a decaying sample of molybdenum-99. 99Mo has a half-life of 66 hours and can be easily transp ...

s to produce the even shorter-lived daughter isotope

, which is used in approximately 40 million medical procedures annually. A common misunderstanding or misnomer is that ⁹⁹Mo is used in these diagnostic medical scans, when actually it has no role in the imaging agent or the scan itself. In fact, ⁹⁹Mo co-eluted with the ^99mTc (also known as breakthrough) is considered a contaminant and is minimised to adhere to the appropriate USP (or equivalent) regulations and standards. The IAEA recommends that ⁹⁹Mo concentrations exceeding more than 0.15 µCi/mCi ^99mTc or 0.015% should not be administered for usage in humans. Typically, quantification of ⁹⁹Mo breakthrough is performed for every elution when using a ⁹⁹Mo/^99mTc generator during QA-QC testing of the final product. There are alternative routes for generating ⁹⁹Mo that do not require a fissionable target, such as high or low enriched uranium (i.e., HEU or LEU). Some of these include accelerator-based methods, such as proton bombardment or

photoneutron Photodisintegration (also called phototransmutation, or a photonuclear reaction) is a nuclear process in which an atomic nucleus absorbs a high-energy gamma ray, enters an excited state, and immediately decays by emitting a subatomic particle. T ...

reactions on enriched ¹⁰⁰Mo targets. Historically, ⁹⁹Mo generated by neutron capture on natural isotopic molybdenum or enriched ⁹⁸Mo targets was used for the development of commercial ⁹⁹Mo/^99mTc generators. The neutron-capture process was eventually superseded by fission-based ⁹⁹Mo that could be generated with much higher specific activities. Implementing feed-stocks of high specific activity ⁹⁹Mo solutions thus allowed for higher quality production and better separations of ^99mTc from ⁹⁹Mo on small alumina column using

chromatography In chemical analysis, chromatography is a laboratory technique for the separation of a mixture into its components. The mixture is dissolved in a fluid solvent (gas or liquid) called the ''mobile phase'', which carries it through a system ( ...

. Employing low-specific activity ⁹⁹Mo under similar conditions is particularly problematic in that either higher Mo loading capacities or larger columns are required for accommodating equivalent amounts of ⁹⁹Mo. Chemically speaking, this phenomenon occurs due to other Mo isotopes present aside from ⁹⁹Mo that compete for surface site interactions on the column substrate. In turn, low-specific activity ⁹⁹Mo usually requires much larger column sizes and longer separation times, and usually yields ^99mTc accompanied by unsatisfactory amounts of the parent radioisotope when using γ-alumina as the column substrate. Ultimately, the inferior end-product ^99mTc generated under these conditions makes it essentially incompatible with the commercial supply-chain. In the last decade, cooperative agreements between the US government and private capital entities have resurrected neutron capture production for commercially distributed ⁹⁹Mo/^99mTc in the United States of America. The return to neutron-capture-based ⁹⁹Mo has also been accompanied by the implementation of novel separation methods that allow for low-specific activity ⁹⁹Mo to be utilized.

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 Molybdenum Molybdenum