Ruthenium-100

Main isotopes of ruthenium

Iso­tope Decay abun­dance half-life (t1/2) mode pro­duct 96Ru 5.54% stable 97Ru syn 2.9 d ε 97Tc γ – 98Ru 1.87% stable 99Ru 12.76% stable 100Ru 12.60% stable 101Ru 17.06% stable 102Ru 31.55% stable 103Ru syn 39.26 d β− 103Rh γ – 104Ru 18.62% stable 106Ru syn 373.59 d β− 106Rh
Standard atomic weight (Ar, standard)	101.07(2)

Naturally occurring ruthenium (₄₄Ru) is composed of seven stable isotopes. Additionally, 27 radioactive isotopes have been discovered. Of these radioisotopes, the most stable are ¹⁰⁶Ru, with a half-life of 373.59 days; ¹⁰³Ru, with a half-life of 39.26 days and ⁹⁷Ru, with a half-life of 2.9 days.

Twenty-four other radioisotopes have been characterized with atomic weights ranging from 86.95 u (⁸⁷Ru) to 119.95 u (¹²⁰Ru). Most of these have half-lives that are less than five minutes, excepting ⁹⁵Ru (half-life: 1.643 hours) and ¹⁰⁵Ru (half-life: 4.44 hours).

The primary decay mode before the most abundant isotope, ¹⁰²Ru, is electron capture and the primary mode after is beta emission. The primary decay product before ¹⁰²Ru is technetium and the primary product after is rhodium.

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