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Topic: Ozone  (Read 18659 times)

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Offline kimyacı

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Ozone
« on: December 19, 2009, 09:42:05 AM »
 Hello all
I wonder about why ozone is not triangular, it is angular.
Thanks in advance...
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Offline Schrödinger

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Re: Ozone
« Reply #1 on: December 19, 2009, 11:39:38 AM »
Think on the following lines
How exactly does a molecule look like?
Would you consider electron pair structure or molecular structure?
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Offline 408

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Re: Ozone
« Reply #2 on: December 19, 2009, 01:03:49 PM »
Think of the bond strain!  On an oxygen-oxygen bond  :o
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Offline Schrödinger

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Re: Ozone
« Reply #3 on: December 19, 2009, 01:04:58 PM »
What bond strain on an oxygen-oxygen bond?
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Offline Grundalizer

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Re: Ozone
« Reply #4 on: December 19, 2009, 10:07:19 PM »


Sure, you could make a triangle out of it.  Draw a line connecting the bottom two Oxygens, and you have one angle of 116.8, and two others of 31.6 degrees.  It just so happens that chemists decided to call a molecule that has a molecular geometry with 3 atoms that has a bond angle of about 120 degrees Bent(angular).

http://en.wikipedia.org/wiki/Molecular_geometry

Why do we call a rock a rock and not a hamster?  Just the name people chose a long time ago.



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Offline 408

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Re: Ozone
« Reply #5 on: December 19, 2009, 10:11:34 PM »
The bond strain on the theoretical triangular ozone molecule.  O-O single bonds even when unstrained are not exactly stable.  Think organic peroxides...
Try forcing the 116.8 degree angle in the bent ozone molecule to the 60 required for a triangular molecule...
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Offline Schrödinger

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Re: Ozone
« Reply #6 on: December 19, 2009, 11:05:20 PM »
Quote from: 408 on December 19, 2009, 10:11:34 PM
Try forcing the 116.8 degree angle in the bent ozone molecule to the 60 required for a triangular molecule...

Why is 60o required for triangular molecule?
Why do you need to force the 116.8 degree angle?
The bond angle has to be 120 for a trigonal planar molecule.
Consider BF3 , SO3 , etc.. Their bond angles are 120, not 60.
See http://en.wikipedia.org/wiki/Trigonal_planar_molecular_geometry


About the bond strain.... The O-O bond length is between that of a single bond and a double bond due to resonance. So, isn't it sort of stronger than the O-O single bond of the peroxide?


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Offline Grundalizer

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Re: Ozone
« Reply #7 on: December 19, 2009, 11:26:27 PM »
Quote
Why is 60o required for triangular molecule?
Why do you need to force the 116.8 degree angle?
The bond angle has to be 120 for a trigonal planar molecule.
Consider BF3 , SO3 , etc.. Their bond angles are 120, not 60.

I agree
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Offline 408

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Re: Ozone
« Reply #8 on: December 20, 2009, 12:14:04 AM »
*Facepalm*

We are thinking two different things...

The original poster wondered why ozone was not 'triangular'. I took this to mean a ring of 3 oxygens singly bonded in a triangular ring, especially as the original poster said ozone is actually angular; which I assumed to be a bad term for a 'bent' molecule.  'Triangular' or 'cyclic' is obviously not the structure of ozone; That is of course as you described; the bent form, which the original poster called 'angular'.  My explanations were for why this cyclic containing 3 oxygens in a ring could not exist.  I never once said ozone actually adopts this cyclic, triangular form, I used the original poster's own terminology in the hopes that he would understand, without having to introduce extra jargon to confuse

*Facepalm*

Way to go...
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Offline sjb

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Re: Ozone
« Reply #9 on: December 20, 2009, 05:00:15 AM »
Just to murky the waters still further, why do both cyclopropane and propene exist? One has the triangle structure (which I too read as being an equilateral triangle), and the other the single/double bond complex?
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Offline BluRay

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Re: Ozone
« Reply #10 on: December 20, 2009, 09:18:54 AM »
Quote from: sjb on December 20, 2009, 05:00:15 AM
Just to murky the waters still further, why do both cyclopropane and propene exist? One has the triangle structure (which I too read as being an equilateral triangle), and the other the single/double bond complex?
Probably because of the same reason you can have both diamond and graphite: in the right conditions, a chemical can assume more than one form, because it has more than one local minimum of gibbs energy.
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Offline Markovnikov

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Re: Ozone
« Reply #11 on: December 21, 2009, 01:05:33 PM »
Quote from: BluRay on December 20, 2009, 09:18:54 AM
Quote from: sjb on December 20, 2009, 05:00:15 AM
Just to murky the waters still further, why do both cyclopropane and propene exist? One has the triangle structure (which I too read as being an equilateral triangle), and the other the single/double bond complex?
Probably because of the same reason you can have both diamond and graphite: in the right conditions, a chemical can assume more than one form, because it has more than one local minimum of gibbs energy.

Please note the difference between an allotrope and an isomer.

To answer the first poster:

PMO theory.
The MO diagram for ozone for a triangular ozone D3h would invoke a second-order Jahn-Teller degeneracy and force the structure to decrease the symmetry towards a less symmetrical structure, the bent structure.
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Offline Schrödinger

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Re: Ozone
« Reply #12 on: December 21, 2009, 01:07:34 PM »
What's PMO theory?

Could you give me a brief intro? Cuz all websites offer long-winding explanations.
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Offline Markovnikov

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Re: Ozone
« Reply #13 on: December 21, 2009, 01:10:57 PM »
Perturbation Molecular Orbital Theory.
Read more here:
http://www.chm.davidson.edu/vce/MolecularOrbitals/index.html

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Offline Schrödinger

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Re: Ozone
« Reply #14 on: December 21, 2009, 01:13:05 PM »
Quote from: Markovnikov on December 21, 2009, 01:10:57 PM
Perturbation Molecular Orbital Theory.
Read more here:
http://www.chm.davidson.edu/vce/MolecularOrbitals/index.html


That's just MO theory. How is PMO different from it?
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"Destiny is not a matter of chance; but a matter of choice. It is not a thing to be waited for; it is a thing to be achieved."
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