Final answer:
The B-F bond in BF₃ is polar covalent due to the large electronegativity difference between boron and fluorine. Despite this, the trigonal planar symmetry causes the molecule to have a net dipole moment of zero, and its Lewis acidity characterizes its electron-accepting properties.
Step-by-step explanation:
The B-F bond in BF₃ with an electronegativity for Boron (B) as 2.0 and an electronegativity for Fluorine (F) as 4.0 is considered polar covalent. This is due to the large electronegativity difference between the two atoms, which signifies significant polar bonds. However, the molecular geometry of BF₃ is trigonal planar. Because of this symmetry and the fact that all B-F bonds are equal, the dipoles in three-dimension cancel each other out. This results in BF₃ having a net dipole moment of zero. Even though BF₃ has polar covalent bonds due to the electronegativity difference, it is also described as an electron-deficient molecule making it a powerful electron acceptor, and a very powerful Lewis acid.