Question

State the VSEPR theory and it's importance

Answer 1

The Valence Shell Electron Pair Repulsion Model is often abbreviated as VSEPR (pronounced “vesper”). It is basically a model to predict the geometry of molecules. Specifically, VSEPR models look at the bonding and molecular geometry of organic molecules and polyatomic ions. It is useful for nearly all compounds that have a central atom that is not a metal.

Importance of VSEPR Models

Lewis structures only tell the number and types of bonds between atoms, as they are limited to two dimensions. The VSEPR model predicts the 3-D shape of molecules and ions but is ineffective in providing any specific information regarding the bond length or the bond itself.VSEPR models are based on the concept that electrons around a central atom will configure themselves to minimize repulsion, and that dictates the geometry of the molecule.

Answer 2

1. The shape of the molecule depends upon the number of electron pair surrounded the central atom.
2. The electron pairs surrounded the central atom repel each other to minimise repulsion the electron tends to stay apart as far as possible.
3. The repulsion interaction between various electron pairs in the order is lp-lp>lp-bp>bp-bp.
4. After repulsion the electron pairs occupy definite positions around the central atom giving a permanent geometry to the molecule.
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