3-Pentenal is an aldehyde with the chemical formula C5H8O, featuring a five-carbon chain with a double bond between the third and fourth carbons, and an aldehyde group at the first carbon. It exists as different stereoisomers, including the (Z)-isomer (or cis isomer) and the (E)-isomer (or trans isomer), which refer to the arrangement of the groups around the double bond.