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Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: shehri on May 03, 2007, 03:41:04 AM

Title: Nature of bonding in CO & CO2
Post by: shehri on May 03, 2007, 03:41:04 AM
Hi friends,

             I want to know the nature of bonding in CO & CO2.Also I'm a bit confused about value of dipole moment in CO.Why Carbon in CO becomes partially -Ve despite Oxygen being more electronegative than Carbon.My text books does'nt provide me required explanations & I'm living such special circumstances that I'm unable to access some chemistry expert.My only source is WWW.Thanks in advance.
Title: Re: Nature of bonding in CO & CO2
Post by: Bakegaku on May 03, 2007, 09:56:05 PM
Hmm.. Well CO has a triple or double bond (can't think of structure right off top of my head).  Since either way the carbon falls short of the number of bonds it must form to be stable (four), it's given the standard charge of -

I believe my chem teacher mentioned when teaching us how to draw Lewis structures that if an element has more bonds than it should, it has a + charge while one less gives it a -.
Title: Re: Nature of bonding in CO & CO2
Post by: ARGOS++ on May 06, 2007, 12:43:47 PM

Dear shehri,

The nature of the CO is one Triplebond, plus for each atom one nonbonding e-paar.
With this in mind you are right, if you think of it as a “clone” of N2, because nearly all physically properties of both are close to indistinguishable.
I know in the moment only one difference of both, as only CO has a recognisable dipole moment, of course not an extremely one, because C (EN = 2.5) and O (EN = 3.5) are quite close together.

CO2 in contrary has not “any” dipole moment, because it is linear in the form: O=C=O with the required nonbonding e-paars on the O. That means that the centres of both charges are located inside the Carbon.
As the molecule is very stable, tells you the corresponding acid will be of very week nature.

I hope, it gives you the wished ideas.

Good Luck!
                    ARGOS++

Title: Re: Nature of bonding in CO & CO2
Post by: Sam (NG) on May 08, 2007, 06:26:21 PM
Argos, is the non-bonding "pair" that you are referring to on each atom the core electrons (1s), because otherwise, according to MO theory, i don't see any non-bonding pairs.
Title: Re: Nature of bonding in CO & CO2
Post by: Yggdrasil on May 08, 2007, 09:17:26 PM
Won't there be an occupied σ*orbital formed from the 2s orbitals?
Title: Re: Nature of bonding in CO & CO2
Post by: Sam (NG) on May 09, 2007, 03:58:11 AM
Won't there be an occupied σ*orbital formed from the 2s orbitals?

Yes, this is antibonding, otherwise the bond order would be 4.
Title: Re: Nature of bonding in CO & CO2
Post by: Yggdrasil on May 09, 2007, 04:24:00 AM
Ah, nevermind my previous comment. I accidentally confused non-bonding with antibonding.
Title: Re: Nature of bonding in CO & CO2
Post by: Sam (NG) on May 09, 2007, 06:14:52 AM
Ah, nevermind my previous comment. I accidentally confused non-bonding with antibonding.

Happens to us all :)