Aldehyde
Aldehydes without rings of carbon are named based on the longest carbon chain containing the aldehyde. Thus, HCHO is named based on methane, and CH3CH2CH2CHO is named based on butane. The name is formed by changing the ending -e of the parent alkane to -al.  HCHO is named methanal.  CH3CH2CH2CHO is named butanal.