Question

Why is `BF_3` an electrophile?

Answer 1

`BF_3` is an electrophile because boron has 3 electrons coupled with 3 electrons coming from three hydrogen atoms, in total 6 electrons in the outer shell. To reach the stable octet configuration it can accept a donated electron couple from a nucleophile, for example `NH_3`. `BF_3` is a Lewis acid.