The f-block consists of elements in which 4 f and 5 f
orbitals are progressively filled They are placed in a
separate panel at the bottom of the periodic table The
names transition metals and inner transition metals
are often used to refer to the elements of d-and
f-blocks respectively There are mainly four series of the transition metals,
3d series (Sc to Zn), 4d series (Y to Cd), 5d series (La
and Hf to Hg) and 6d series which has Ac and elements
from Rf to Cn