BF three has three HS attached to the boron, and the boron has an empty orbital. And this empty orbital is what interacts with the lone pair of electrons on our H, forming our corticovalent bond. So in this case, the BF three accepted the pair of electrons because it had that anti orbital. So the BF three is our lewis acid. So another way to talk about a lewis acid is to say that a lewis acid is either neutral or a cation. In this case, it was neutral that has an empty orbital.