Why does the simplest ketone have three carbon atoms and no fewer?
1 answer
A ketone is R2C=O; therefore, if we make R1 a CH3 group (the simplest) and the second R group a CH3 group, that makes 3 C atoms. If you take one of the R groups and try to make it smaller (like making it a H atom), one ends up with RCHO and that is an aldehyde, not a ketone.