Explain how the elements are classified into s, p, d and f - block elements in the periodic table and give the advantage of this kind of classification.
Depending on the valency shell electronic configuration elements are classified into s,p,d and f - block elements.
s-block elements : The elements with valence shell electronic configuration ${{ns}^{1}}$ and ${{ns}^{2}}$ are called s-block elements.
p - block elements : The elements with valence shell electronic configuration ${{ns}^{2}}$${{np}^{6}}$ are called p-block elements.
s and p-block elements together known as representative elements, d - block elements : The elements with valence electronic configuration from ${{ns}^{2}}$${{np}^{6}}$(n - l)${{d}^{1}}$ to ${{ns}^{2}}$${{np}^{6}}$ (n - l)${{d}^{10}}$ are called d-block elements. These are also called as transition elements.
f - block elements : The elements in which f - orbitals are being filled in their atoms are called f - block elements. These are also known as Inner Transition elements.
Advantage : This division of elements into blocks is useful to divide the elements into groups. Every group has the elements with some valence electronic configuration. They have similar chemical properties,
s - block elements - IA and IIA groups
p - block elements - IIIA to VIIIA or zero group
d- block elements - IB to VIII B groups
f - block elements - Lanthanoids and Actinoids