Question

Define octet rule. Write its significance and limitations.

Answer 1

The octet rule is a chemical rule of thumb that reflects observation that atoms of main-group elements tend to combine in such a way that each atom has eight electrons in its valence shell, giving it the same electronic configuration as a noble gas.

Answer 2

Answer :

Octet rule: Atoms of elements combine with each other in order to complete their respective octets so as to acquire the stable gas configuration.

$\rule{150}{2}$

Significance: It helps to explain why different atoms combine with each other to form ionic compounds or covalent compounds.

$\rule{200}{2}$

Limitations of Octet rule:

(1). According to Octet rule, atoms take part in chemical combination 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: XeF2, XeF4 etc.

Therefore, validity of the octet rule has been challenged.

(2). This theory does not account for shape of molecules.