Answer. In aldehydes the carbonyl carbon is attached with at least one hydrogen atom while in ketone it is attached on both sides with alkyl groups. For example, functional group of aldehyde is:
O
II
-C-H
While, the functional group of ketone is:
C==== O
Examples are;
O O
║ ║
H-C-H H3C-C-H
Form aldehyde Acetaldehyde
O O
II II
H3C-C-CH3 H3C-C-CH2-CH3
Acetone (Dimethyl ketone) Ethyl methyl ketone