Lone Pairs and Molecular Shape

[Sean Sugai 4E]

In a molecule with lone pairs, the valence electrons play a role in electron arrangement about the central atom. How do lone pair electrons distort the shape of a molecule?

[Vincent Leong 2B]

To think about it in a molecular sense, it's less of the valence electrons distorting the atom's shape and more of the atom's respective effective nuclear charge or the amount of positive attraction the valence electrons experience from another atom's positive nucleus. The unequal attraction of electrons on one side of one atom vs the other side of the atom is what leads to the electron cloud being distorted.

[pmokh14B]

The other atoms will be repelled by the lone electrons. The bonds between the central atom and peripheral ones contain negatively charged electrons which will tend to move as far as possible from the concentrated negative charge of the unpaired e-.

[Khushboo_3D]

According to the VSEPR theory, lone pairs of electrons repel each other and therefore should be placed as far apart from each other as possible, thus impacting shape of the molecule.
The textbook also states it precisely as, "Lone pairs distort the shape of a molecule so as to reduce lone pair–bonding pair repulsions."