Isotopes of molybdenum

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There are 35 known isotopes of molybdenum (Mo) ranging in atomic mass from 83 to 117, 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, five are stable, with atomic masses from 94 to 98. All unstable isotopes of molybdenum decay into isotopes of niobium, technetium, and ruthenium.[1]

Molybdenum-92 and molybdenum-100 are the only naturally occurring isotopes which are 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. Molybdenum isotopes with mass numbers from 111 to 117 all have half-lives of approximately .15 μs.[1]
Standard atomic mass: 95.94(2) u

Table

nuclide
symbol
Z(p) N(n)  
isotopic mass (u)
 
half-life 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] 3/2-#
84Mo 42 42 83.94009(43)# 3.8(9) ms [3.7(+10-8) s] 0+
85Mo 42 43 84.93655(30)# 3.2(2) s (1/2-)#
86Mo 42 44 85.93070(47) 19.6(11) s 0+
87Mo 42 45 86.92733(24) 14.05(23) s 7/2+#
88Mo 42 46 87.921953(22) 8.0(2) min 0+
89Mo 42 47 88.919480(17) 2.11(10) min (9/2+)
89mMo 387.5(2) keV 190(15) ms (1/2-)
90Mo 42 48 89.913937(7) 5.56(9) h 0+
90mMo 2874.73(15) keV 1.12(5) µs 8+#
91Mo 42 49 90.911750(12) 15.49(1) min 9/2+
91mMo 653.01(9) keV 64.6(6) s 1/2-
92Mo 42 50 91.906811(4) STABLE [>190E+18 a] 0+ 0.1477(31)
92mMo 2760.46(16) keV 190(3) ns 8+
93Mo 42 51 92.906813(4) 4.0(8)E+3 a 5/2+
93mMo 2424.89(3) keV 6.85(7) h 21/2+
94Mo 42 52 93.9050883(21) STABLE 0+ 0.0923(10)
95Mo 42 53 94.9058421(21) STABLE 5/2+ 0.1590(9)
96Mo 42 54 95.9046795(21) STABLE 0+ 0.1668(1)
97Mo 42 55 96.9060215(21) STABLE 5/2+ 0.0956(5)
98Mo 42 56 97.9054082(21) STABLE [>100E+12 a] 0+ 0.2419(26)
99Mo 42 57 98.9077119(21) 2.7489(6) d 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 42 58 99.907477(6) 8.5(5)E+18 a 0+ 0.0967(20)
101Mo 42 59 100.910347(6) 14.61(3) min 1/2+
102Mo 42 60 101.910297(22) 11.3(2) min 0+
103Mo 42 61 102.91321(7) 67.5(15) s (3/2+)
104Mo 42 62 103.91376(6) 60(2) s 0+
105Mo 42 63 104.91697(8) 35.6(16) s (5/2-)
106Mo 42 64 105.918137(19) 8.73(12) s 0+
107Mo 42 65 106.92169(17) 3.5(5) s (7/2-)
107mMo 66.3(2) keV 470(30) ns (5/2-)
108Mo 42 66 107.92345(21)# 1.09(2) s 0+
109Mo 42 67 108.92781(32)# 0.53(6) s (7/2-)#
110Mo 42 68 109.92973(43)# 0.27(1) s 0+
111Mo 42 69 110.93441(43)# 200# ms [>300 ns]
112Mo 42 70 111.93684(64)# 150# ms [>300 ns] 0+
113Mo 42 71 112.94188(64)# 100# ms [>300 ns]
114Mo 42 72 113.94492(75)# 80# ms [>300 ns] 0+
115Mo 42 73 114.95029(86)# 60# ms [>300 ns]

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.

References

  1. 1.0 1.1 Lide, David R., ed. (2006), CRC Handbook of Chemistry and Physics, 11, CRC, pp. 87–88, 0-8493-0487-3

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