Do not draw structures like this in Chem. 211

Dr. Engel 8/27/15

The circle is an attempt to show both resonance structures at once. However, it is not possible to push curved arrows on this structure.

CO O

O

- -

C

C

C

C

If you draw this, you have to show the hydrogens thusly: C

CH3H3C

CH3

H

OH H

OH H

_

We like We don't like

Do not show lone pairs as lines because they are too easily confused with bonds and negative charges.

C O C O+

only 6 e- on C but no charge separation

all octets but has charge separation

don't write

Holy smokes; which one is better? Answer: experimentally, the dipole moment points from O to C so C is the negative end of the molecule. Octets must be really important, considering that we are placing the + charge on the more electronegative atom.

Finally, consider carbon monoxide.

This is an attempt to show all three resonance strucure of carbonate at once. However, it is also impossible to push curved arrows on dashed line structures.

_

_