ABSTRACT
The elements of Group 9 are cobalt (Co), rhodium (Rh), and iridium (Ir). Co belongs to the iron family metals, which includes also Fe and Ni, previously in the Group VIII. Rh and Ir are noble metals of the platinum group (PGMs). According to the IUPAC recommendation, these elements belong to the Group 9. All three metals exhibit variable properties, siderophilic and/or lithophilic characters, and variable oxidation states (Table 14.1).
