Question

Knowing that F is more electronegative than either B or P what conclusion can be drawn from the fact that BF3 has no dipole moment but PF3 does?

A. BF3 is not spherically symmetrical but PF3 is

B. The BF3 molecule must be trigonal planar

C. The BF3 molecule must be linear

D. The atomic radius of P is larger than the atomic radius of B

Please explain

Answer 1

In BF₃ the B atom undergoes sp² hybridization with 3 bond pairs & no lone pairs so the shape of the molecule is trigonal planar thereby the net dipolemement cancel each other so it has no dipolement.

Where as in PF₃ the P atom undergoes sp³ hybridization with 3 bond pairs & 1 lone pair so the shape of the molecule is pyramidal thereby the net dipolemement is along the fourth vertix of the tetrahedran so it has some net dipolement.

Therefore option(B) is correct.