Final answer:
In BF3, sp² orbitals are formed by the hybridization of Boron's atomic orbitals. These orbitals can bond with fluorine's orbitals to form B-F bonds in the trigonal planar molecule.
Step-by-step explanation:
The sp² hybrid orbitals in BF3 refer to the hybridization of Boron's atomic orbitals to form three sp² hybrid orbitals. Each sp² orbital can bond with a 2p orbital from a fluorine atom to form the trigonal planar BF3 molecule. The geometry of these orbitals is trigonal planar, with the lobes pointing towards the corners of a triangle, and the angle between any two lobes is 120°.
For example, when a paired 2s electron in Boron is promoted to the empty 2py orbital, it results in the formation of sp² orbitals. These sp² orbitals can then overlap with fluorine's orbitals to form the B-F bonds in BF3.
It is worth noting that BF3 can also form BF4 by bonding with a fluorine ion, completing boron's octet. The formation of BF4 exemplifies the preference for complete octets in nature.