i) Octet rule : "The atoms of element tend to undergo chemical changes that help to leave their atoms with eight outer shell electrons".
ii) I really appreciate the octet rule. Eight electrons in the outermost shell definitely, gives stability to ion (or) atom.
iii) Chemically active elements do not have an octet of electrons in the valence shell of their atoms.
iv) Their reactivity arises from their tendency to achieve the octet, by forming bonds either with atoms of their own type or with atoms of other elements.