Question

Based on which factor are the elements classified into four blocks?

Answer 1

Classification of blocks:-

• The elements in the periodic table are classified into four blocks, namely s-block, p-block, d-block, and f-block.
• This classification is done based on which orbital of the atoms the last electron enters.
• The elements in which the last electron enters the s-orbitals are called the s-block elements.

s-Block Elements:

• The general electronic configuration of s-blocks are ${\mathrm{ns}}^{(1-2)}$
• For example Sodium has an electronic configuration $1{\mathrm{s}}^{2}2{\mathrm{s}}^{2}2{\mathrm{p}}^{6}3{\mathrm{s}}^1$.
• We can see that the last electron is in the s-orbital, thus it is an s-block element.

p-Block Elements:

• The elements in which the last electron enters the p-orbitals are called the p-block elements.
• The general electronic configuration of p-blocks are ${\mathrm{ns}}^2{\mathrm{np}}^{(1-6)}$
• For example Aluminium has an electronic configuration $1{\mathrm{s}}^{2}2{\mathrm{s}}^{2}2{\mathrm{p}}^{6}3{\mathrm{s}}^{2}3{\mathrm{p}}^1$.

d-Block Elements

• The elements in which the last electron enters the d-orbitals are called the d-block elements.
• The general electronic configuration of d-blocks are $(\mathrm{n}-1){\mathrm{d}}^{(1-10)}{\mathrm{ns}}^{(0-2)}$
• For example Cobalt has an electronic configuration $1{\mathrm{s}}^{2}2{\mathrm{s}}^{2}2{\mathrm{p}}^{6}3{\mathrm{s}}^{2}3{\mathrm{p}}^{6}3{\mathrm{d}}^{7}4{\mathrm{s}}^2$.

f-Block Elements

• The elements in which the last electron enters the f-orbitals are called the f-block elements.
• The general electronic configuration of f-blocks are $(\mathrm{n}-2){\mathrm{f}}^{(0-14)}(\mathrm{n}-1){\mathrm{d}}^{(0-10)}{\mathrm{ns}}^2$
• For example Uranium has an electronic configuration $1{\mathrm{s}}^{2}2{\mathrm{s}}^{2}2{\mathrm{p}}^{6}3{\mathrm{s}}^{3}3{\mathrm{p}}^{6}3{\mathrm{d}}^{10}4{\mathrm{s}}^{2}4{\mathrm{p}}^{6}4{\mathrm{d}}^{10}4{\mathrm{f}}^{14}5{\mathrm{s}}^{2}5{\mathrm{p}}^{6}5{\mathrm{d}}^{10}5{\mathrm{f}}^{3}6{\mathrm{s}}^{2}6{\mathrm{p}}^{6}6{\mathrm{d}}^{1}7{\mathrm{s}}^2$.