Question

Given a molecular formula of a molecule what do you need to accomplish in order to determine the molecular geometry, or shape, of a compound?

Answer 1

The molecular geometry of a compound can be determined by valence shell electron pair repulsion (VSEPR)theory.

For example :1) CH4

In this molecule, carbon has 4 Bond pairs with 4 hydrogens and carbon involves sp3 hybridisation and has tetrahedron structure

2) NH3 , here N has one lone pair and 3 Bond pairs with 3 hydrogens so totally 4 electron pairs and the geometry according to VSEPR theory is pyramidal.

Hence the shape of a molecule is determined by VSEPR theory.