Molecular geometry describes and predicts the arrangement of atoms in a molecule.

When dealing with very simple molecules such as methane (CH₄), water (H₂0), or Ammonia (NH₃) the rules and principles of molecular geometry accurately predict the shapes of the molecules. As molecules become increasingly complex it becomes very difficult -- but not impossible -- to predict and describe complex geometric arrangements of atoms.

The number of bonds between atoms, the types of bonds, and the presence of lone electron pairs on the central atom in the molecule influence the arrangement of atoms about the central atom in a molecule.

Use of valance shell electron pair repulsion theory (VSEPR) allows chemists to predict the shape of a molecule. According to VESPR theory, molecules will be shaped so as to minimize repulsion between electrons. (Repulsion between valence electrons causes these pairs to be as far apart as...