What is the chemical structure of propanal?

Propanal, also known as propionaldehyde, is an aldehyde with the molecular formula C₃H₆O. Its structure consists of three carbon atoms: two of these are part of a linear chain while the third is part of the aldehyde functional group, which is characterized by the carbonyl group (C=O) located at the end of the carbon chain.

The correct structure, representing propanal, is CH₃-CH₂-CHO. In this structure, the CH₃ (methyl group) indicates the first carbon, the CH₂ (methylene group) represents the second carbon, and the CHO (aldehyde group) indicates the terminal carbon that contains the carbonyl group along with a hydrogen atom. This arrangement directly corresponds to the nomenclature of propanal, as it is a three-carbon aldehyde.

The other structures listed represent different compounds that do not conform to the definition of propanal. This understanding is crucial in organic nomenclature as it highlights the importance of functional groups and their positioning within the carbon chain to accurately name and identify organic molecules.