VSEPR Theory and Smallest F-X-F Angle

VSEPR theory stands for Valence Shell Electron Pair Repulsion theory. It is a model that predicts the geometry of molecules based on the repulsion between electron pairs in the valence shell. The theory states that electron pairs will orient themselves in such a way as to minimize repulsion between them.

The F-X-F angle refers to the angle between two fluorine atoms in a molecule. The species with the smallest F-X-F angle will be the one with the most repulsion between the two fluorine atoms.

Option A: BF3

- BF3 has a trigonal planar geometry.
- It has three bond pairs and no lone pairs of electrons.
- The F-B-F angle is 120°.

Option B: PF3

- PF3 has a trigonal pyramidal geometry.
- It has three bond pairs and one lone pair of electrons.
- The F-P-F angle is 96.3°.

Option C: BF4-

- BF4- has a tetrahedral geometry.
- It has four bond pairs and no lone pairs of electrons.
- The F-B-F angle is 109.5°.

Option D: IF4-

- IF4- has a square planar geometry.
- It has four bond pairs and one lone pair of electrons.
- The F-I-F angle is 90°.

Conclusion

From the above analysis, it can be concluded that the species with the smallest F-X-F angle is option B: PF3, which has a F-P-F angle of 96.3°.