Resonance of HCO3^- and sigma/pi bonds

In summary: Thanks for the help so far, Geoff. I am only supposed to list two equivalent (I assume that might be the key word there) resonance forms.it's from first year university chemistry - just very out of my element.
  • #1
lorka150
39
0
Are two equivalent resonance forms HCO3^- like this?
... O
...//
O - C
...\
... O - H


...O - H
.../
O - C
...\\
...O


Both structures have brackets and a -.
Also, each O on the left has six dots, the O on the double bond has four, and the O on the H has four as well. Sorry about the ... I didn't know how else to 'draw' them so they would line up.

Are there four sigma and 1 pi?

Thanks.
 
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  • #2
lorka150 said:
Are two equivalent resonance forms HCO3^- like this?
... O
...//
O - C
...\
... O - H


...O - H
.../
O - C
...\\
...O


Both structures have brackets and a -.
Also, each O on the left has six dots, the O on the double bond has four, and the O on the H has four as well. Sorry about the ... I didn't know how else to 'draw' them so they would line up.

Are there four sigma and 1 pi?

Thanks.
The two structures you have drawn are not resonance structures. You have simply rotated the molecule 180 degrees along the horizontal axis. Try to remember that, when drawing resonance structures, only electrons can move (not atoms).
 
  • #3
Thanks Geoff... In that case, I'm quite confused.
 
  • #4
lorka150 said:
Thanks Geoff... In that case, I'm quite confused.
Keep the molecule oriented the same in all resonance structures. In other words, the H must stay on the same O.

What level of chemistry is this question from? Are you required to list only major resonance structures, or all of them?
 
  • #5
Thanks for the help so far, Geoff. I am only supposed to list two equivalent (I assume that might be the key word there) resonance forms.
it's from first year university chemistry - just very out of my element.

... O
...//
O - C
...\
... O - H


...O
.../
O - C
...\\
...O -H

Is that what you are indicating?
 
  • #6
lorka150 said:
Thanks for the help so far, Geoff. I am only supposed to list two equivalent (I assume that might be the key word there) resonance forms.
it's from first year university chemistry - just very out of my element.

... O
...//
O - C
...\
... O - H...O
.../
O - C
...\\
...O -H

Is that what you are indicating?

Although these are resonance structures, they are certainly not equivalent.

Why do you think the double bond will shift to the O with an H attached?
 
Last edited:
  • #7
lorka150 said:
Thanks for the help so far, Geoff. I am only supposed to list two equivalent (I assume that might be the key word there) resonance forms.
it's from first year university chemistry - just very out of my element.

... O
...//
O - C
...\
... O - H...O
.../
O - C
...\\
...O -H

Is that what you are indicating?

Try rotating the molecule so that the alcohol is pointing to the left.

Code:
     O
    //
H-O-C
     \
      O

Give the equivalent resonance structure of the molecule. I'll assume you can see it now.
 
Last edited:

1. What is the significance of the resonance of HCO3-?

The resonance of HCO3- plays a crucial role in stabilizing the molecule and maintaining its structure. It allows for the delocalization of the negative charge among the different atoms, making the molecule more stable and less reactive.

2. How does the resonance of HCO3- affect its bond lengths?

The resonance of HCO3- causes the bond lengths to be between single and double bonds, resulting in a hybrid structure. This hybrid structure helps to evenly distribute the negative charge and make the molecule more stable.

3. Can sigma and pi bonds coexist in the resonance of HCO3-?

Yes, the resonance of HCO3- involves both sigma and pi bonds. The sigma bonds are formed by the overlapping of atomic orbitals, while the pi bonds are formed by the overlapping of p orbitals.

4. How does the resonance of HCO3- contribute to its acidic properties?

The resonance of HCO3- makes the molecule more acidic by stabilizing the negative charge on the oxygen atom. This makes it easier for the molecule to donate a proton and act as an acid.

5. Can the resonance of HCO3- be observed experimentally?

No, the resonance of HCO3- cannot be directly observed in experiments. However, its effects can be observed through techniques such as spectroscopy and X-ray crystallography, which can provide information about the bond lengths and bond angles in the molecule.

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