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I am trying to determine the electron pair geometry (and molecular geometry) of some atoms in ibuprofen. The first one I am trying to do is the double bonded oxygen. Ibuprofen is pictured below:enter image description here

I counted the number of electron domains (steric number)to be 3. I counted the double bond as one and each lone pair as one. It has two lone pairs and one double bond. So this means the electron geometry should be trigonal planar. But I am stuck on molecular geometry. There is no molecular geometry I have found in any chart that has two lone pairs and one bond. Am I making a mistake somewhere? Any help is greatly appreciated!

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    $\begingroup$ I assume you are trying to apply the VSEPR model. In that case you are correct in assuming two lone pairs, a sigma and a pi bond for oxygen, giving a trigonal arrangement in the surrounding of oxygen. Be aware, that this model is very crude and the bonding situation is much closer to $\sigma-\ce{C_{sp^2}-O_{sp}}$, $\pi-\ce{C_{p}-O_{p}}$, $\sigma-\mathrm{LP}-\ce{O_{sp}}$ and $\pi-\mathrm{LP_{inplane}}-\ce{O_{p}}$. $\endgroup$ – Martin - マーチン Jan 20 '15 at 4:02
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You are right! There is no molecular geometry in any chart that has two lone pairs and one bond, because the only possible geometry with one neighboring atom is linear. The central atom in a chemical moiety must have at least two neighboring atoms in order to predict the geometry around this central atom (according to VSEPR model). Let's take the case of oxygen atom of the hydroxyl group (in Ibuprofen). The oxygen atom here, as a central atom, has the steric number: 4 ( It has two lone pairs and two simple bonds with carbon and hydrogen atoms). So, The molecular geometry around oxygen atom is bent.

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