unctional group- collection of atoms at a site within a molecule with a common bonding pattern The group reacts in a typical way, generally independent of the rest of the molecule For example the double bonds in simple and complex alkenes react with bromine in the same way OH CH C C H Reaction site Double bond• Functional group - collection of atoms at a site within a molecule with a common bonding pattern • The group reacts in a typical way, generally independent of the rest of the molecule • For example, the double bonds in simple and complex alkenes react with bromine in the same way