Resonance Structures for Species of the Form XO4
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Resonance stabilization is a major part of valence bond theory. This is how this
particular method handles electron delocalization. In all these species, the X-O bonds are
equivalent even though the individual Lewis structures contain both single and double
bonds.
When considering these systems, we need to do the following:
1) Write the possible Lewis structures and
2) Count the number of equivalent forms each one has.
3) Note that single-bonded oxygens have a formal charge of -1 and that double-
bonded oxygens have a formal charge of 0.
We start with the simplest case first. Here all the bonds are single bonds. Here is the
structure. It should be obvious that it can have only one resonance form or, to put this
another way, there is no resonance at all.
Now, let us look at the case where there is a single double bond in the individual Lewis
structures. We show this now.
This has four equivalent resonance structures. This might be easier to visualize if we
make a 3D rendering.
