Electronic Geometry vs. Molecular Geometry

(Polar molecules, Non-polar molecules, etc.)

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Andy Liao 1B
Posts: 52
Joined: Thu Jul 13, 2017 3:00 am

Electronic Geometry vs. Molecular Geometry

Postby Andy Liao 1B » Sun Nov 12, 2017 6:02 pm

Can someone please tell me how to clearly differentiate between electronic geometry and molecular geometry? Sometimes I mix the two up.

Grace Ramey 2K
Posts: 57
Joined: Thu Jul 27, 2017 3:01 am

Re: Electronic Geometry vs. Molecular Geometry

Postby Grace Ramey 2K » Sun Nov 12, 2017 6:11 pm

I believe that electronic geometry, or "electronic arrangement", refers to the shape of the molecule regarding the positions of electron density, while molecular geometry or shape only takes actual atoms into account (not the electron density of a lone pair, for example). As an example, a sulfate ion, SO3 2-, has three oxygen atoms bonded to the sulfur atom, plus one lone pair on the sulfur atom. This gives 4 regions of electron density total, which gives a tetrahedral electron arrangement (this takes the lone pair into account). However, to give the molecular shape or geometry, only the actual atoms are counted, and therefore the shape would be trigonal pyramidal (which doesn't technically doesn't take the lone pair, since it is not an atom).

Hope this helps!

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