Lewis structures and the shapes of molecules

Creating the Lewis structures of molecules is a method for determining the sequence of bonding within a molecule and its three-dimensional shape. This works best for covalently bonded molecules, but can also work for ionic compounds. For example, this method can be used to explain why the sequence of bonding in water is H-O-H, rather than H-H-O, and why it has a bent structure, rather than linear. 

The rules used to draw Lewis structures are as follows  

Bond type, order, length, and resonance structures 

As described above for molecular oxygen or nitrogen, it is possible to have more than one bond between atoms (up to a maximum of three for orbital reasons). Bond order is simply the number of pairs of electrons shared between two atoms (remember there are two electrons per covalent bond). As the bond order increases the distance between the atoms decreases and the energy required to break the bonds increases. 

As seen in Section 10.4, the quantum numbers determine the electronic configuration of the atom and also the shape of the atomic orbitals (Fig. 

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