How many π bonds are in a molecule of boron trifluoride?
You can write four Lewis structures for
In one structure, the
The other three structures have double bonds to the
Most texts say that the double bond structures do not occur, because they put a positive charge on the
However, resonance theory says that when you can write more than one Lewis structure for a molecule, the actual structure is a resonance hybrid of them all.
The double bonded structures may be minor contributors, but they still contribute a little bit.
In that sense, the
Furthermore, the length of the
This is consistent with some degree of π bonding in