Molecular Resonance Through Systemic Functional Linguistics [3]

Gribbin (1988: 131-2):

One very common substance whose structure depends on resonance and hybridisation is the carbonate ion CO₃⁻⁻, found in common chalk, the shells of sea creatures, and limestone. … How can you arrange four electrons from the carbon atom. six from each of the oxygen atoms, and the two extra electrons in the most stable state?

There are three possibilities, variations on the same theme like the two ozone variations on the tri-atomic oxygen theme. … The three possibilities are equivalent and have the same energy as each other.  Because the bonds are different, each of those three possibilities would be asymmetrical, and the asymmetry would show up in spectroscopic measurements.  Once again, however, the measurements show that the carbonate ion is perfectly symmetrical.  Three bonds, each equivalent to 1.333 normal bonds, are arranged at 120° to one another uniformly around the carbon atom.  The carbonate ion is a resonance hybrid.

Blogger Comments:

From the perspective of Systemic Functional Linguistic theory, the two single bonds and one double bond between one carbon atom and three oxygen atoms in the carbonate ion CO₃⁻⁻ constitute the potential of the carbonate ion as a whole, and so apply equally to all three chemical bonds, yielding the "hybrid" potentials of each bond.