Question

the BF3 molecule is planar. the attachment of a fluoride ion to the boron in BF3 through a coordinate covalent bond, creates the BF4 ion. What is the geometric shape of this ion?

Answer 1

The geometry of BF₄⁻ anion is tetrahedral

Step-by-step explanation:

According to the Valence Bond Theory, the boron atom in BF₃ molecule is sp² hybridized. As one 2s and two 2p orbitals hybridize to form three sp² hybrid orbitals.

Therefore, the molecular geometry of BF₃ molecule is trigonal planar.

However, in a BF₄⁻ ion, the boron atom is sp³ hybridized. As it forms four sp³ hybrid orbitals by hybridization of one 2s and three 2p orbitals.

Therefore, the molecular geometry of BF₄⁻ anion is tetrahedral.

Answer 2

The shape here is tetrahedral.The central atom here is located at the center of the attached substituents (4) which are placed at the corner of the tetrahedron. The bond angles here is 109.4712206° ≈ 109.5° given that all attachments are of the same kind like methane.