What are the different oxidation states exhibited by the lanthanoids?
The lanthanoids exhibit different oxidation states, with the +3 oxidation state being the most common and stable. This is evident from the fact that many trivalent lanthanoid ions exist and are well-documented.
In addition to the +3 state, some lanthanoids also exhibit +2 and +4 oxidation states. For instance, Cerium (Z = 58) is well known to exhibit the +4 oxidation state (Ce⁴⁺). Similarly, Ytterbium shows the +2 oxidation state (Yb²⁺). The +3 state remains predominant, with more compounds in this state than in the +4 state.
Explanation
The textbook context provides specific examples of lanthanoid oxidation states. The +3 state is established as the most common (evident from references to 'many trivalent lanthanoid ions' and comparison with actinoids 'having more compounds in +3 state than in the +4 state'). The +4 state is exemplified by Cerium (Example 4.10), and the +2 state is indicated by Yb²⁺ mentioned in the paramagnetic properties discussion. This covers the key oxidation states exhibited by lanthanoids.