What is the of clf3?

Answer 1

"Trigonal bipyramidal. There are 5 pairs of electrons. 3 bonding pairs and two lone pairs. Therefore the shape which minimizes repulsions is trigonal bipyramidal."

This is slightly inaccurate. The geometry is trigonal bipyramidal but since there are two lone pairs of electrons, the molecule is T-shaped. The 2 lone pairs occupy equatorial positions. What I cannot find out yet is why the lone pairs are equatorial and not axial.

Note the axial positions are slightly distorted from 180 degrees due to the fact that non bonding electron lone pairs have stronger repulsions than bonded electron pairs.

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The person who answered the question said "I cannot find out yet is why the lone pairs are equatorial and not axial." Here's why:

In a trigonal bipyramidal ELECTRON geometry, you have three pairs at equatorial positions which means the angle between them is 120 degrees and you have two pairs at axial positions with angle of 90 degrees to the plane where you have the equatorial electron pairs. (If you want to see what I mean, search for the image "trigonal bipyramidal.") Now, recall that lone pairs are the most repulsive, "wanting" to be as far away as possible from the other electron pairs in order to minimize repulsion. So, they must be at the position with the greatest angle (120 degrees)... which is at an equatorial position.