Posted by Rachel on Thursday, January 20, 2011 at 3:57pm.
Does anyone know where I can get an image of the valence bond model for maleic acid?
ie. showing the pi and sigma bonds and indicating the hybridization (sp2, sp3.. )
OR could someone describe these things to me?
I'm just trying to check my work and make sure I didn't miss anything
__________________________________________________________________
Chemistry - DrBob222, Thursday, January 20, 2011 at 8:29pm
OH bonds are linear (sp)
O=CH2 are sp2
R2CH2 are sp3.
C=C are sp2
__________________________________________________________________
I'm clear on everything except the 3rd statement:
R2CH2 are sp3.
Could you clarify the R? And where does this bond occur on the molecule? I have it drawn out.. but this isn't popping out at me.
Chem- Dr. Bob! - DrBob222, Saturday, January 22, 2011 at 8:47pm
There are no R2CH2 bonds in maleic acid. R stands for something other than a functional group; i.e.,
CH3CH2OH is ethanol but if I want to designate an alcohol in general, I can write RCH2OH. So this could be many many other alcohols (propanol, butanol, pentanol, etc). The R is just a convenient way to write a general formula. I was trying to get at the CH bonds on maleic acid. Those CH bonds are linear. I have searched and can't find an image for you. That doesn't mean there isn't one; I just haven't found it.
COOH
|
C-H
||
C-H
|
COOH
___________________________________________________________________
Chem- Dr. Bob! - Rachel, Saturday, January 22, 2011 at 9:03pm
Oh! Okay, I'm familiar with R groups on amino acids etc..
The question just asks me to label the hybridization for each carbon and oxygen atom. So here's what I've got:
The carbon atoms bonded to eachother are sp2 hybridized atoms.
The carbon atoms bonded double bonded to the oxygens are sp2 hybridized atoms.
And the oxygen atoms bonded to the carbon and hydrogen are sp hybridized atoms.
The only atoms I'm not sure about are the oxygen atoms double bonded to the carbon atoms.
And I don't have any sp3 hybridized atoms ...?
Can you please critique my work
All of the C atoms are sp2 hybridized. There are no sp3 hybrid C atoms.
From this conversation, it seems like Rachel is having trouble finding an image of the valence bond model for maleic acid and wants clarification on the hybridization of the atoms in the molecule. Although the image couldn't be found, DrBob222 provided some information about the hybridization of the atoms in maleic acid.
According to DrBob222, the OH bonds are linear, which means they are sp hybridized. The O=CH2 bonds are sp2 hybridized. As for the C=C bonds, they are also sp2 hybridized.
However, there was some confusion about the statement "R2CH2 are sp3" because there are no R2CH2 bonds in maleic acid. DrBob222 explained that R is used to represent something other than a functional group, just a convenient way to write a general formula. In this case, the CH bonds in maleic acid are linear.
In her response, Rachel labels the hybridization for each carbon and oxygen atom as follows:
- The carbon atoms bonded to each other are sp2 hybridized atoms.
- The carbon atoms double bonded to the oxygen atoms are also sp2 hybridized atoms.
- The oxygen atoms bonded to the carbon and hydrogen are sp hybridized atoms.
However, she wasn't sure about the oxygen atoms double bonded to the carbon atoms and couldn't find any sp3 hybridized atoms in the molecule.
To critique Rachel's work, we can confirm that the carbon atoms bonded to each other and the carbon atoms double bonded to oxygen are indeed sp2 hybridized. The oxygen atoms bonded to carbon and hydrogen are sp hybridized.
Regarding the oxygen atoms double bonded to the carbon, maleic acid contains two of these double bonds. In the valence bond model, these double bonds will consist of one sigma bond and one pi bond. Since the carbon atoms involved in these double bonds already have three sigma bonds (two with other carbon atoms and one with hydrogen), they are already sp2 hybridized. Therefore, the oxygen atoms double bonded to carbon will also be sp2 hybridized.
As for not finding any sp3 hybridized atoms in maleic acid, it appears to be correct. Maleic acid is a molecule that consists only of sp and sp2 hybridized atoms.
By analyzing and critiquing Rachel's work, we were able to clarify the hybridization of the atoms in maleic acid.