What is the chemical structure of a carbonyl group?

The carbonyl group is characterized by a functional group containing a carbon atom double-bonded to an oxygen atom, which is represented by the structure C=O. This functional group is fundamental in organic chemistry and is found in various compounds, including aldehydes and ketones, which play essential roles in biological systems and metabolic processes.

The carbonyl group features a carbon atom that is sp2 hybridized, leading to a planar structure. The presence of the double bond contributes to the polarity of the carbonyl bond, as oxygen is more electronegative than carbon. This polarity often makes carbonyl groups reactive, particularly in nucleophilic addition reactions, which are crucial for biological chemistry and biochemical pathways.

The other structural representations listed do not accurately depict a carbonyl group. For instance, a simple C-O representation lacks the double bond, which is essential for defining the carbonyl. C=C denotes a carbon-carbon double bond, unrelated to carbonyl functionality. Lastly, C-H shows a single bond between carbon and hydrogen, which also does not relate to the carbonyl structure. Therefore, the structure C=O uniquely identifies the carbonyl group.