Aldehydes and Ketones

Aldehydes and ketones contain a carbonyl group (>C=O), and are collectively called carbonyl compounds.

Aldehydes

In aldehydes, one end of the carbonyl group is attached to an alkyl (or aryl) group and the other is to a hydrogen atom.

Here R and Ar represent alkyl and aryl groups respectively. In condensed structural formulae, the carbonyl group of an aldehyde is represented as −CHO.

Ketones

In ketones, both the ends of carbonyl group are attached to alkyl or aryl groups.

Important Points Regarding Carbonyl Groups

• The carbon atom of carbonyl group is sp² hybridised and has trigonal planar structure.
• Since the electronegativity of oxygen is higher than that of carbon, the C=O bond is polar.
• The carbonyl group exhibits resonance :
  

Nomenclature ^{_{of Aldehydes and Ketones}}

Rules for naming aldehydes and ketones are discussed in nomenclature of aldehydes and ketones. If you want to learn nomenclature from the very beginning, start from nomenclature introduction.