Are bf3 and nf3 symmetrical or unsymmetrical molecules? explain.

Boron trifluoride (BF3) and Nitrogen trifluoride (NF3) are not symmetrical. BF3 molecules have a Trigonal Planar shape whereas NF3 molecules have a Trigonal Pyramidal shape.

This is because of a difference in the central atoms of each molecule, in this case Boron and Nitrogen. Nitrogen has a lone pair of electrons in its outer shell after making bonds with each Fluorine atom. The negative charge on this lone pair pushes the three Fluorine atoms downward creating the Pyramid shape. Boron however does not have a lone pair after bonding with the three Fluorine atoms and therefore they lie on the same plane as the Boron atom.