Alcohols are a family of compounds that contain carbon, hydrogen and oxygen. Each molecule has an -OH group joined to a carbon chain. The first four members are methanol, ethanol, propanol (propan-1-ol) and butanol (butan-1-ol), which have one, two, three and four carbon atoms.
Their formulae are CH3OH, C2H5OH, C3H7OH and C4H9OH. Each one has one more carbon atom than the one before. For propanol, three carbon atoms carry seven hydrogen atoms in the chain, and the OH group adds one more, so one molecule has eight hydrogen atoms in total.
When you draw an alcohol showing all the covalent bonds, every bond is a single bond. Each carbon atom forms four bonds, each oxygen atom forms two bonds and each hydrogen atom forms one bond. The oxygen sits in the OH group, with one bond to a carbon atom and one bond to a hydrogen atom.
