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Isotopes of molybdenum

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For MO99 Freon mix R438A, see Refrigerant.

There are 33 known isotopes of molybdenum (Mo) 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. Of these naturally occurring isotopes, six (all but 100Mo) have never been observed to decay, but all are theoretically capable of radioactive decay. All unstable isotopes of molybdenum decay into isotopes of zirconium, niobium, technetium, and ruthenium.[1]

Molybdenum-100 is the only naturally occurring isotope that is not stable. Molybdenum-100 has a half-life of approximately 1×1019 y and undergoes double beta decay into ruthenium-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 µs.[1]

Relative atomic mass: 95.95(1).[2]

Table

nuclide
symbol 		Z(p) N(n)  
isotopic mass (u)
  		half-life[n 1] decay
mode(s)[3][n 2] 		daughter
isotope(s)[n 3] 		nuclear
spin 		representative
isotopic
composition
(mole fraction) 		range of natural
variation
(mole fraction)
excitation energy
83Mo 42 41 82.94874(54)# 23(19) ms
[6(+30-3) ms] 		β+ 83Nb 3/2−#
β+, p 82Zr
84Mo 42 42 83.94009(43)# 3.8(9) ms
[3.7(+10-8) s] 		β+ 84Nb 0+
85Mo 42 43 84.93655(30)# 3.2(2) s β+ 85Nb (1/2−)#
86Mo 42 44 85.93070(47) 19.6(11) s β+ 86Nb 0+
87Mo 42 45 86.92733(24) 14.05(23) s β+ (85%) 87Nb 7/2+#
β+, p (15%) 86Zr
88Mo 42 46 87.921953(22) 8.0(2) min β+ 88Nb 0+
89Mo 42 47 88.919480(17) 2.11(10) min β+ 89Nb (9/2+)
89mMo 387.5(2) keV 190(15) ms IT 89Mo (1/2−)
90Mo 42 48 89.913937(7) 5.56(9) h β+ 90Nb 0+
90mMo 2874.73(15) keV 1.12(5) µs 8+#
91Mo 42 49 90.911750(12) 15.49(1) min β+ 91Nb 9/2+
91mMo 653.01(9) keV 64.6(6) s IT (50.1%) 91Mo 1/2−
β+ (49.9%) 91Nb
92Mo 42 50 91.906811(4) Observationally Stable[n 4] 0+ 0.14649(106)
92mMo 2760.46(16) keV 190(3) ns 8+
93Mo 42 51 92.906813(4) 4,000(800) y EC 93Nb 5/2+
93mMo 2424.89(3) keV 6.85(7) h IT (99.88%) 93Mo 21/2+
β+ (.12%) 93Nb
94Mo 42 52 93.9050883(21) Stable[n 5] 0+ 0.09187(33)
95Mo[n 6] 42 53 94.9058421(21) Stable[n 5] 5/2+ 0.15873(30)
96Mo 42 54 95.9046795(21) Stable[n 5] 0+ 0.16673(30)
97Mo[n 6] 42 55 96.9060215(21) Stable[n 5] 5/2+ 0.09582(15)
98Mo[n 6] 42 56 97.9054082(21) Observationally Stable[n 7] 0+ 0.24292(80)
99Mo[n 6][n 8] 42 57 98.9077119(21) 2.7489(6) d β− 99mTc 1/2+
99m1Mo 97.785(3) keV 15.5(2) µs 5/2+
99m2Mo 684.5(4) keV 0.76(6) µs 11/2−
100Mo[n 9][n 6] 42 58 99.907477(6) 8.5(5)×1018 a β−β− 100Ru 0+ 0.09744(65)
101Mo 42 59 100.910347(6) 14.61(3) min β− 101Tc 1/2+
102Mo 42 60 101.910297(22) 11.3(2) min β− 102Tc 0+
103Mo 42 61 102.91321(7) 67.5(15) s β− 103Tc (3/2+)
104Mo 42 62 103.91376(6) 60(2) s β− 104Tc 0+
105Mo 42 63 104.91697(8) 35.6(16) s β− 105Tc (5/2−)
106Mo 42 64 105.918137(19) 8.73(12) s β− 106Tc 0+
107Mo 42 65 106.92169(17) 3.5(5) s β− 107Tc (7/2−)
107mMo 66.3(2) keV 470(30) ns (5/2−)
108Mo 42 66 107.92345(21)# 1.09(2) s β− 108Tc 0+
109Mo 42 67 108.92781(32)# 0.53(6) s β− 109Tc (7/2−)#
110Mo 42 68 109.92973(43)# 0.27(1) s β− (>99.9%) 110Tc 0+
β−, n (<.1%) 109Tc
111Mo 42 69 110.93441(43)# 200# ms
[>300 ns] 		β− 111Tc
112Mo 42 70 111.93684(64)# 150# ms
[>300 ns] 		β− 112Tc 0+
113Mo 42 71 112.94188(64)# 100# ms
[>300 ns] 		β− 113Tc
114Mo 42 72 113.94492(75)# 80# ms
[>300 ns] 		0+
115Mo 42 73 114.95029(86)# 60# ms
[>300 ns]
  1. ^ Bold for isotopes with half-lives longer than the age of the universe (nearly stable)
  2. ^ Abbreviations:
    EC: Electron capture
    IT: Isomeric transition
  3. ^ Bold for stable isotopes
  4. ^ Believed to decay by β+β+ to 92Zr with a half-life over 1.9×1020 years
  5. ^ a b c d Believed to be capable of spontaneous fission
  6. ^ a b c d e Fission product
  7. ^ Believed to decay by β−β− to 98Ru with a half-life of over 1×1014 years
  8. ^ Used to produce the medically useful radioisotope technetium-99m
  9. ^ Primordial radionuclide

Notes

  • Geologically exceptional samples are known in which the isotopic composition lies outside the reported range. The uncertainty in the atomic mass may exceed the stated value for such specimens.
  • Values marked # are not purely derived from experimental data, but at least partly from systematic trends. Spins with weak assignment arguments are enclosed in parentheses.
  • Uncertainties are given in concise form in parentheses after the corresponding last digits. Uncertainty values denote one standard deviation, except isotopic composition and standard atomic mass from IUPAC, which use expanded uncertainties.

Applications

Molybdenum-99 is produced commercially by intense neutron-bombardment of a highly purified uranium-235 target, followed rapidly by extraction.[4] It is used as a parent radioisotope in technetium-99m generators to produce the even shorter-lived daughter isotope technetium-99m, which is used in many medical procedures.

References

  1. ^ a b D. R. Lide, ed. (2006). CRC Handbook of Chemistry and Physics. Vol. 11. CRC Press. pp. 87–88. ISBN 0-8493-0487-3.
  2. ^ "Standard Atomic Weights 2013". Commission on Isotopic Abundances and Atomic Weights.
  3. ^ "Universal Nuclide Chart". nucleonica. {{cite web}}: Unknown parameter |registration= ignored (|url-access= suggested) (help)
  4. ^ Frank N. Von Hippel; Laura H. Kahn (December 2006). "Feasibility of Eliminating the Use of Highly Enriched Uranium in the Production of Medical Radioisotopes". Science & Global Security. 14 (2 & 3): 151–162. doi:10.1080/08929880600993071. Retrieved 2010-03-26.
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