Explain why non-bonded pairs of electrons affect the shape of a molecule.

Answer 1

According to Valence Shell Electron Pair Repulsion (VSEPR) theory, bonded and non-bonded pairs of electrons in a central atom tend to achieve a configuration to minimize repulsion between pairs of electrons.

2 electron pairs linear arrangement

3 electron pairs trigonal planar arrangement

4 electron pairs tetrahedral arrangement etc.

For example, if a central atom has two bonded pair electrons and two non-bonded pairs, the electron pairs will tend to achieve a close to tetrahedral arrangement, but the two bonded pairs will result in a bent molecular shape. Read up on VSEPR theory to get a better picture.