Class 11 Chemistry - Chapter Chemical Bonding and Molecular Structure NCERT Solutions | Discuss the shape of the following molec

Welcome to the NCERT Solutions for Class 11th Chemistry - Chapter Chemical Bonding and Molecular Structure. This page offers a step-by-step solution to the specific question from Exercise 1, Question 7: discuss the shape of the following molecules using....
Question 7

Discuss the shape of the following molecules using the VSEPR model:

BeCl2, BCl3, SiCl4, AsF5, H2S, PH3

Answer

Valence shell electron pair repulsion (VSEPR) theory:

It is a model used to predict the 3D geometry of individual molecules from the number of electron pairs surrounding their central atoms. It was developed by Gillespie & Nyholm. The various geometries are as follows according to number of lone pair present:

 

BeCl2:

The central atom has no lone pair and there are two bond pairs. i.e., BeCl2 is of the type EX2. Hence, it has a linear shape.

 

BCl3:

The central atom has no lone pair and there are three bond pairs. Hence, it is of the type EX3. Hence, it is trigonal planar.

 

SiCl4:

The central atom has no lone pair and there are four bond pairs. Hence, the shape of SiCl4 is tetrahedral being the EX4 type molecule.

 

AsF5:

The central atom has no lone pair and there are five bond pairs. Hence, AsF5 is of the type EX5. Therefore, the shape is trigonal bipyramidal.

 

H2S:

The central atom has one lone pair and there are two bond pairs. Hence, H2S is of the type AB2E. The shape is Bent.

 

PH3:

The central atom has one lone pair and there are three bond pairs. Hence, PH3 is of the EX5 type. Therefore, the shape is trigonal bipyramidal.

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