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Square planar shape

Posted: Wed Nov 21, 2018 6:12 pm
by Samantha Chung 4I
For a trigonal bipyramidal general shape, we would place the lone pairs on the equatorial axis because it has least repulsion with the surrounding axial atoms, as there are two axial atoms. However, for the square planar shape, why then do we place the two lone pairs on the two opposite ends, would not that repel the surrounding four atoms in the other plane?

Re: Square planar shape

Posted: Wed Nov 21, 2018 8:20 pm
by Brian Cook
Trigonal bipyramidal involves five regions of electron density whereas square planar involves six, so I used the octahedral shape as my starting point, and as you can see based off the model you can exchange the "top" and "bottom" atom bonds and make them lone pair electrons, which would result in that square planar shape.