The octet rule or the electronic theory of chemical bonding was developed by Kossel and Lewis. According to this rule, atoms can combine either by transfer of valence electrons from one atom to another or by sharing their valence electrons in order to attain the nearest noble gas configuration by having an octet in their valence shell.
The octet rule successfully explained the formation of chemical bonds depending upon the nature of the element.
Limitations of the octet theory:
The following are the limitations of the octet rule:
(a) The rule failed to predict the shape and relative stability of molecules.
(b) It is based upon the inert nature of noble gases. However, some noble gases like xenon and krypton from compounds such as XeF2, KrF2 etc.
(c) The octet rule cannot be applied to the elements in and beyond the third period of the periodic table. The elements present in these periods have more than eight valence electrons around the central atom. For example: PF5, SF6, etc.
(d) For atoms in a molecule having an odd number of electrons, octet rule is not applied. E.g. For NO2 and NO octet rule is not applicable.
(e) If a compound is having less than 8 electrons surrounding the central atom than octet rule cannot be applied to that compound. E.g. BeH2, AlCl3, LiCl etc. is not obeying octet rule.
Answered by Abhisek | 1 year ago