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 1×1019y 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
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
^ ab Lide, David R., ed. (2006), CRC Handbook of Chemistry and Physics, vol. 11, CRC, pp. 87-88, 0-8493-0487-3
Isotope masses from Ame2003 Atomic Mass Evaluation by G. Audi, A.H. Wapstra, C. Thibault, J. Blachot and O. Bersillon in Nuclear Physics A729 (2003).
National Nuclear Data Center, Brookhaven National Laboratory. Information extracted from the NuDat 2.1 database (retrieved Sept. 2005).
David R. Lide (ed.), Norman E. Holden in CRC Handbook of Chemistry and Physics, 85th Edition, online version. CRC Press. Boca Raton, Florida (2005). Section 11, Table of the Isotopes.