Why are lanthanides and Actinides are placed sepatately at the bottom of the peridic table ?

Explanation

(1) The lanthanides and the actinides constitutes the f - block of the periodic table . And they belong 3B group . The electonic configuration of these elements is (n-2 `f ^(1-14 ) (n-1 ) d^(0-1) ns^(2) ` . The lanthanides are the elements formed by filling electrons in 4F orbital and the elements in the '3B ' group are formed by filling electrons in 'd ' orbital
(2 ) these lanthanides and actinides belongs to f- block elements with different properties
(3 ) Due the these reasons the two series which form f- block of the periodic table are placed separely in the periodic table .