When the central atom has 4 bonding pairs of electron the geometry is tetrahedral. All of the bond angles are 109.5Ü.
When the central atom has 3 bonding pairs of electrons and 1 nonbonding pair the geometry is trigonal pyramidal.
When the central atom has 2 bonding pairs of electrons and 2 nonbonding pair the geometry is bent.
Although bent is used to describe the molecular geometry for a molecule with a central atom having 2 bonding pairs of electrons and 2 non-bonding pairs, it is also used to describe the molecular geometry for a molecule with a central atom having 2 bonding pairs of electrons and 1 nonbonding pair. The difference is in the bond angle.
