Question

What is the functional group of an aldehyde?

Answer 1

Hint : We know that the carbon is double bonded to the oxygen atom and hydrogen it attached to it. This functional group is very similar to ketones and they both undergo similar reactions. Aldehydes and ketones are organic compounds that have a carbonyl functional group.

Complete Step By Step Answer:
To answer this question firstly we have to discuss what a functional group is. In organic chemistry, functional groups are specific substituents in molecules which are responsible for the characteristic reaction of that molecule. The same functional groups will undergo similar reactions regardless of the type of molecule it is attached to.
Basically, a functional group is the identity of a certain class of compounds. We know alcohol, ketone, aldehyde, ester, ether and many more functional groups in organic chemistry. Molecules with alcohol functional groups will undergo similar kinds of reaction as other molecules with the same functional group.
Aldehydes are compounds where the carbonyl group has one hydrogen atom attached to it along with either a second hydrogen atom or a hydrocarbon group that can be an alkyl group or a group containing a benzene ring. The smallest aldehyde is formaldehyde. The most common example of an aldehyde is formaldehyde, which is $HCHO.$
This is true for any other functional group too. Now let us identify the functional group given to us. The functional group given to us is $CHO.$ The carbonyl carbon is attached to the oxygen atom which has a hydrogen atom. This functional group is known as an aldehyde. $CHO$ is the characteristic functional group of aldehydes. Here, the carbon occupied in the carbonyl center (a carbon atom double bonded to an oxygen atom) is also attached to a hydrogen atom, giving us a $CHO$ group and there can be other substituents on the carbon atom.

Note :
Remember that aldehydes are very similar to ketones. The only difference is ketones have a ‘R’ group instead of the hydrogen atom. Aldehydes with maximum four carbons (as well as ketones) are soluble in water due to the possibility of hydrogen bonding. Higher aldehydes (and ketones) do not dissolve in water. Aldehydes undergo reactions similar to ketones like halogenation, oxidation, reduction etc.