Shape of Molecules-

Shapes of a molecule is quite accurately predicted by VSEPR theory.

According to this theory, all valence shell e- surrounding the central atom arrange themselves in such a manner so as to be as far away from each other as possible.

By separating e-s from each other, electrostatic repulsion is minimized.

Valence shell pair of e-s is arranged, so that these are at maximum separation among regions of high e- density (bond pairs) about the atom.

For instance, two regions of high e- density would be most stable on opposite side of central atom, i.e. the linear arrangement.

While three regions of high e- density would be most stable on when they are arranged at corner of an equilateral triangle.

Bond Angles also depends on geometry of a molecule and hence VSEPR theory plays a big role in important characteristics like Hybridization and Bond Angle.