Isotopes of rhodium
Naturally occurring rhodium (Rh) is composed of only one stable isotope, Rh. The most stable radioisotopes are Rh with a half-life of 3.3 years, Rh with a half-life of 207 days, and Rh with a half-life of 16.1 days. Thirty other radioisotopes have been characterized with atomic weights ranging from 88.949 u (Rh) to 121.943 u (Rh). Most of these have half-lives that are less than an hour except Rh (half-life: 20.8 hours) and Rh (half-life: 35.36 hours). There are also numerous meta states with the most stable being Rh (0.141  MeV) with a half-life of about 3.7 years and Rh (0.157 MeV) with a half-life of 4.34 days. The primary decay mode before the only stable isotope, Rh, is electron capture and the primary mode after is beta emission. The primary decay product before Rh is ruthenium and the primary product after is palladium.