A homologous series is a group of compounds with the same general formula and similar chemical properties.
A hydrocarbon is a compound made up of only hydrogen and carbon particles.
Saturated means that a compound is made up of only single bonds, it has no double bonds. Alkanes are a homologous series of saturated hydrocarbons.
Unsaturated means that a compound includes double bonds. Alkenes are a homologous series of unsaturated hydrocarbons.
A general formula is a type of empirical formula that represents of all of the members of a homologous series.
Isomers are molecules with the same chemical formula but different structures (e.g. diamond and graphite are both carbon, but are very different because they are isomers)
