Question

Name the member of the lanthanide series which is well known to exhibit a \( +4 \) oxidation state. 

Hint:

Cerium ({Ce}) is the only lanthanide that {readily forms} the \( +4 \) oxidation state due to its {stable noble gas configuration} ({[Xe]}).

Answer 1

Step 1: Understanding the Lanthanide Series 
The lanthanides (or rare earth elements) consist of 15 elements from lanthanum (La) to lutetium (Lu) in the periodic table. 
Step 2: Oxidation States of Lanthanides 
- The common oxidation state of lanthanides is \( +3 \).
- However, some lanthanides can exhibit other oxidation states, such as:
- \( +2 \) (e.g., Eu, Yb, Sm)
- \( +4 \) (e.g., Ce, Tb) 
Step 3: Why Cerium Exhibits \( +4 \) Oxidation State 
- Electronic configuration of cerium: \[ [{Xe}] 4f^1 5d^1 6s^2 \] - In the \( +4 \) oxidation state, cerium loses all its valence electrons: \[ [{Xe}] \] - This stable xenon-like configuration makes Ce\(^4+\) stable. 
Step 4: Conclusion 
Among lanthanides, cerium (Ce) is the most common element to exhibit a \( +4 \) oxidation state.