How do aldehydes differ from ketones?

Aldehydes and ketones contain a double bond between carbon and oxygen.

Aldehydes have a double bond at the end of the molecule. This means that the carbon at the end of the chain has a double bond with the oxygen atom.

Ketones have a double bond anywhere in the molecule except at the end. This means that you will see a double bond with oxygen from one of the carbons in the middle of the chain.

If you are unsure if a substance is an aldehyde or a ketone, you can use Tollen’s reagent. Tollen’s reagent has the formula [Ag (NH3) 2] NO3 and can oxidize aldehydes but not ketones.