Question

What are inner transition(f-block) elements? Give two examples.

Answer 1

The elements in which the valence electron enters in anti penultimate energy level i.e., (n - 2) f are known as f - block elements. This name is because of the position of the valence electron is in the f - orbital. Since the last electron enters into (n - 2)f - orbital which is inner to the penultimate shell, they are also called inner transition elements. Hence, the general electronic configuration for these elements is

$(n-2)f^{1-14}(n-1)d^{0-1}n{s}^2$

Examples are: Cerium and Thorium