Structure Of Aldehydes and Ketones

Both aldehydes and ketones contain a C=O functional group. The aldehyde functional group is found at the end of a chain with the last carbon containing a C=O and one hydrogen. A ketone, on the other hand, contains a C=O group somewhere within the compound. The C=O group is attached to a carbon and nothing else (as shown below).

Upon naming the compounds, there are 2 differences, aldehydes are named with the end -al. For example ethanal and propanal. On the other hand, ketones end in -one. For example propanone and butanone. However, to be more precise the a number is used to show where the carbonyl compound in placed within the molecule.

The carbonyl functional group and the atoms attached are in the same plane. This produces a bond angle of about 120°. The carbon-oxygen (C=O) bond length is about 120pm in aldehydes and ketones.