As has already been indicated, alkanes are relatively unreactive. For an organic molecule to be reactive it needs something additional. A site of reactivity in an organic molecule is called a functional group. C=C double is a functional group. Other functional groups contain elements other than C or H, notably O, N and Cl. A functional group could be an atom or a group of atoms within a molecule that is responsible for its characteristic chemical reactions.Alkanes

Only carbon and hydrogen All single bonds Their names end with -ane Alkenes Only carbon and hydrogen A carbon to carbon double bond Their names end with -ene Alkynes Only carbon and hydrogen A carbon to carbon triple bond Their names end with -yne Alcohols Only one oxygen Has an O-H group Can be classified as 1/2/3 according to position of O-H group on carbon skeleton They are named as alkanol Aldehydes Only one oxygen Has a C=O group C=O group is at the end of the carbon chain, so is next door to a hydrogen atom They are named as alkanalKetones Only one oxygen Has a C=O group C=O group is not at the end of carbon chain, so is next door to 2 carbons They are named as alkanoneEsters Has 2 oxygens One oxygen is part of a C=O bond, the other is next door, sandwiched between two carbons. They are named as Alkylalkanoatecarboxylic acids Has 2 oxygens Has O-H and C=O groups on the same carbon atom This -COOH group has to be at the end of a carbon chain. They are named as alkanoic acidEther Has 1 oxygen No O-H or C=O group The oxygen is sandwiched between two carbon atoms Their names end with -etherAmines Contain Nitrogen Has an NH2 group Can be classified as 1/2/3 according to the number of carbon atoms connected to the N They are named as alkyl amineAmide Has NH2 and C=O groups on the same carbon atom They are named as alkanamideHaloalkanes Have the general formula R-X where R is an alkyl group and X is a halogen They are named as haloalkanes