Question

Why are f-block elements called "Inner-transition elements" ?

Answer 1

The f- block elements are known as inner transition elements because they involve the filling of inner sub-shells (4f or 5f). Their electronic configuration has a f-orbital (or they have valence electrons f-orbitals). These include Lanthanide and Actinide series in the periodic table.

1. Lanthanides: It consists of elements that follow lanthanum and involve the filling of 4f subshell.

2. Actinides: It consists of elements that follow Actinium and involve the filling of 5f subshell.