Octet rule:
"The atoms of elements tend to uderrgo chemical changes that help to leave their atoms with eight outer-shell electrons."
Chemically active elements do not have an octet of electrons in the valence shell of their atoms.Their reactivity arises from their tendency to achieve the octet,forming bonds either with atoms of their own types or with atoms of other elements.Therefore its role can be appreciated.
i hope this helps you ! plzzz mark besttttttt...!!!