Final answer:
The dipole moment of boron trifluoride (BF3) remains zero both before and after it undergoes Lewis acid-base interaction with an F- ion due to its symmetrical geometry that persists even after the interaction.
Step-by-step explanation:
The question concerns the dipole moment of a molecule when it interacts with fluoride ions (F-). The specific molecule in question is boron trifluoride (BF3). It is important to understand that the dipole moment of a molecule is a measure of the separation of charge within that molecule and is affected by its geometry and the electronegativity of its atoms.
BF3 is a molecule with a trigonal planar geometry, which means it has a symmetrical shape. All the B-F bonds are of equal length and boron and fluorine have a significant difference in electronegativity, resulting in dipoles for each B-F bond. However, due to the symmetrical arrangement of these bonds, the individual dipole moments cancel each other out, resulting in a net dipole moment of zero.
When BF3 interacts with an F- ion, it undergoes a Lewis acid-base interaction and forms the tetrahedral ion BF4-. This changes the geometry and symmetry, potentially affecting the dipole moment. However, since all four B-F bonds remain identical and the molecule retains symmetry, the dipole moment remains zero even after the interaction with F-.