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

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

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