[SPASH]

While is it that when you draw the lewis structure for BF3, that one of the bonds does not change to a double bond like it does when you draw H2CO??

BF3 is an exception in that the B atom only has 6 electrons, not 8.

Any help would be great!

Thank you!!

[Winga]

The valence e- of B in BF3 is 6.
B is sp2 hybridized leaving one unhybridized p-orbital to accept a lone pair from Lewis base, BF3 is Lewis acid.

In reality, a lone pair from F will donate to B froming a pi bond, but not permanent, just resonance. Every F in BF3 participates in the resonance effect.