Boron trifluoride, BF₃(g), is commonly employed as a Lewis-acid catalyst in organic synthesis. A researcher wants to rationalize its molecular structure in terms of electron bookkeeping and the octet rule.
(a) Determine the total number of valence electrons that must be represented in a complete Lewis diagram for one molecule of BF₃.
(b) Draw a complete Lewis diagram for BF₃, clearly indicating all bonding pairs and lone pairs of electrons.
(c) Explain, in terms of both electron count and the relative electronegativities of the bonded atoms, why the central boron atom does not attain an octet in the structure you drew in part (b).
(d) Propose an alternative Lewis diagram in which at least one B–F bond is depicted as a multiple bond. Evaluate whether this alternative is likely to be a major contributor to the actual electronic structure of BF₃, citing energetic or conceptual arguments to support your claim.