Trigonal Planar Geometry

Trigonal planar geometry is a molecular geometry model with three atoms surrounding a central atom in a flat, equilateral triangle. The bond angle is 120°, and the geometry is symmetrical. Molecules with trigonal planar geometry have no lone pairs of electrons on the central atom.

Explanation

Out of the given options, only BF3 has trigonal planar geometry. In BF3, the central atom is boron, and it has three bonded atoms of fluorine. There are no lone pairs of electrons on boron, and the three fluorine atoms are arranged symmetrically around the boron atom in a flat, equilateral triangle. Therefore, BF3 has trigonal planar geometry.

On the other hand, NH3, PCl3, and IF3 do not have trigonal planar geometry. NH3 has a tetrahedral geometry with one lone pair of electrons on the central atom, nitrogen. PCl3 has a trigonal pyramidal geometry with one lone pair of electrons on the central atom, phosphorus. IF3 has a T-shaped geometry with two lone pairs of electrons on the central atom, iodine.

Conclusion

In summary, BF3 has trigonal planar geometry, and the other options do not. To determine the geometry of a molecule, we need to identify the central atom, the bonded atoms, and the lone pairs of electrons on the central atom. Based on this information, we can use VSEPR theory to predict the molecular geometry.