Define Octet rule. Write its significance and limitations.

Explanation

Octet rule: Atoms of elements combine with each other in order to complete their respective octet so as to acquire the stable nearest noble gas configuration.
Significance: It helps to explain why different atoms combine with each other to form ionic compounds or covalent compounds.
Limitations of Octet rule:
(i) According to octet rule, atoms take part in chemical eombination to achieve the configuration of nearest noble gas elements. However, some of noble gas elements like Xenon have formed compounds with fluorine and oxygen. For example: `XeF_(2), XeF_(4) XeO_(3)` etc. Therefore, validity of the octet rule has been challenged.
(ii) This theory does not account for the shapes of molecules.