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Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: g13 on April 10, 2010, 10:06:17 PM

Title: Molecular Geometry
Post by: g13 on April 10, 2010, 10:06:17 PM

Hey so I'm working on the structure XeF3- and have been trying to figure out its Molecular geometry.
I realize it has octahedron Electron geometry but as for the M.G. I haven't been able to find anything that satisfies 3 bonding pairs and 3 lone pairs.

My best guess is that it is trigonal planar because of the pattern the electrons would make(first taking the axial places, then the first equitorial place), but I'm open to better interpretations if anyone has one.

Title: Re: Molecular Geometry
Post by: imanooblar on April 11, 2010, 02:30:12 PM

It's T Shaped for Molecular Geometry.

(https://www.chemicalforums.com/proxy.php?request=http%3A%2F%2Fcourses.unt.edu%2Fmschwartz%2Fchime%2Fxef3.gif&hash=d79f162887eee52b5a61d539771fcf8106c15fcd)

Title: Re: Molecular Geometry
Post by: Schrödinger on April 11, 2010, 11:55:25 PM

LP=Lone pair
BP=Bond pair

To minimise the LP-LP repulsions(LP-LP > LP-BP > BP-BP repulsions), two axial places have to occupied, and one equatorial place will be occupied by the remaining LP.
Having two LPs in the equatorial position next to each other will cause more repulsion, since the angle of separation is just 90^o as compared to 180^o when they are in the axial positions

T-shaped is the right structure (distorted ofcourse)