an AB 2 E 2 molecule. Here, the oxygen atom is at the center of a tetrahedron, with
two corners occupied by hydrogen atoms and two by the unshared pairs, as shown
below. Again, VSEPR theory states that the lone pairs occupy space around the
central atom but that the actual shape of the molecule is determined only by the
positions of the atoms. In the case of water, this results in a “bent,” or angular,
molecule.
VSEPR and Molecular Geometry
The following table summarizes the molecular shapes associated with particular
types of molecules. Notice that, in VSEPR theory, double and triple bonds are
treated in the same way as single bonds. It is helpful to use the Lewis structures
and this table together to predict the shapes of molecules with double and triple
bonds, as well as the shapes of polyatomic ions.
TIP
Know these molecular and Lewis structures.Summary of Molecular Shapes