"Mo-99" redirects here. For MO99 Freon mix R438A, see
refrigerant .
Nuclides with atomic number of 42 but with different mass numbers
Molybdenum (42 Mo) has 39 known isotopes , ranging in atomic mass from 81 to 119, as well as four metastable nuclear isomers . 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 , niobium , technetium , and ruthenium .[ 5]
Molybdenum-100, with a half-life of approximately 8.5×1018 y , is the only naturally occurring radioisotope. It 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 s.[ 5]
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