Final answer:
The suffix used for ketone groups in IUPAC naming is -one.
Step-by-step explanation:
The suffix used for ketone groups in IUPAC naming is -one.
The longest chain containing the ketone group is chosen as the parent name, with the last 'e' of the suffix replaced with -one.
For example, propan-2-one is the IUPAC name for a ketone with a ketone group attached to the second carbon in a three-carbon chain.