F- ion can react with BF3, forming the BF4- anion. In this reaction, 1)the F- ion acts as a Brønsted base, accepting a proton from BF3 molecule. 2) the F- ion acts as a Lewis base, donating a proton to the BF3 molecule. 3) the F- ion acts as a Brønsted acid, donating a proton to the BF3 molecule 4) the BF3 molecule acts as a Lewis acid, accepting an electron pair from the F- ion to form a coordinate covalent bond. 5) the BF3 molecule acts as a Lewis base, donating an electron pair to the F- ion to form a coordinate covalent bond.