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 1×10
19 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
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 ...
-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, Stable
[Theoretically 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 Stable
[Believed to decay by β−β− to 98Ru with a half-life of over 1×1014 years]
, 0+
, 0.24292(80)
,
, -
,
99Mo
[Used 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)×10
18 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
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 ...
, 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