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Topic: Bond angles  (Read 7805 times)

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Offline disruptive

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Bond angles
« on: February 06, 2009, 02:31:18 PM »
This may be a simple question for a chemist. However, I wish to know the know the bond angle between carbon atoms in an acid for example palmitic acid. Each carbon in the main chain (not at the ends), has four bond emanating from it: two to other carbons and two to hydrogens. However I do not know what configuration the carbon is in? I presume it is sp3 hybridized because it makes four bonds. That would imply bond angles of 109.4 degrees? Have I missed something?

As a follow up, for a CIS bonded acid such as oleic acid, how would I determine the kink angle along the chain?

Thanks
« Last Edit: February 06, 2009, 02:47:17 PM by disruptive »

Offline cundi

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Re: Bond angles
« Reply #1 on: February 07, 2009, 04:02:55 AM »
109.4 is the exact angle for a perfect tetrahedro. For example CH4, or CBr4.
All carbons with four bonds have a sp3 hybridation but when all of this are not thes same it is not a perfect tetrahedro (it implies a non exact angle of 109.4) .If you want to know an angle in a molecule (aprox.) you can minimize the energy of this molecule with a MM program.
Chem3D (chemoffice) offers you this posibility.

Offline nielsgeode

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Re: Bond angles
« Reply #2 on: February 07, 2009, 06:03:39 AM »
109.4 is the exact angle for a perfect tetrahedro. For example CH4, or CBr4.
All carbons with four bonds have a sp3 hybridation but when all of this are not thes same it is not a perfect tetrahedro (it implies a non exact angle of 109.4) .If you want to know an angle in a molecule (aprox.) you can minimize the energy of this molecule with a MM program.
Chem3D (chemoffice) offers you this posibility.

That is a theoretical approach which is not exact of course. The best experimental way to determine bond angle's is single crystal x-ray diffraction but you have to crystallize the compound your interested in first.

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