Discussion:
Resonance Forms of BF3
The question goes like this. Boron often forms compounds that do not comply with the octet rule that are termed electrondeficient. BF3, whose structure is shown below on the left, is an example of an electron deficient compound. Note that the central boron atom is only surrounded by 6 valence electrons. The resonance structure shown on the right brings all atoms into compliance with the octect rule. Does this Lewis structure make a substantial contribution to the electronic structure of BF3? Explain your answer.
F F F - F
/ /
B B
! !!
F F
+
The exclamation mark is being used in place of a bond on the left structure and a double bond on the right.
I don't know if the diagrams will show up well. On the right is B surrounded by three F's with single bonds. On the right is B surrounded by three F's with the bond being double on one F and single with the other two. The one on the right also has a negative charge on top and a positive charge on the bottom. The charges are not placed on the F's but on the molecule as a whole.