aldehydes & ketones have a carbonyl group- which is a carbon double bonded to an oxygen atom (C=O)

aldehyde- when the carbonyl group is at the end of the chain

ketone- when the carbonyl group is in the middle of the chain or in a ring

some common ketones are: propanone (acetone) & cyclohexanone

some common aldehydes are: methanal (formaldehyde), ethanal (acetaldehyde), benzaldehyde

the carbonyl group is very polar

• this makes aldehydes & ketones up to 3-4 carbons in length miscible in water

they are less soluble in water and have lower boiling points than alcohols

• more soluble in water and have higher boiling points than ethers & hydrocarbons

aldehydes & ketones undergo addition reactions at the carbon-oxygen double bond called nucleophilic addition

• this is different from alkene addition because the carbonyl double bond is polar while alkenes have a non-polar pi bond

ketones can’t be further oxidized but aldehydes can be oxidized to carboxylic acids