To solve the problem, we need to understand what the 4f elements are called.
1. The 4f Elements:
The 4f elements are elements whose electrons fill the 4f orbital. These elements belong to the lanthanide series and are also known as lanthanoids.
2. Conclusion:
The 4f elements are called Lanthanoids.
Final Answer:
The 4f elements are called $ {\text{Lanthanoids}} $.