2-3 Functional Groups:Centers of Reactivity em onasAetwedreertomso0aor9n8ne8ecp66ah Cl-cits c-cH:HC-cH c-cacH onyo unds of hydrogen and carbon which contair mples of the classo o. Many functional groups contain polar bonds adslfcompondrmed a upsecule in the4 2-3 Functional Groups: Centers of Reactivity Functional groups are groups of atoms at sites of comparatively high chemical reactivity. They control the reactivity of the molecule as a whole. Hydrocarbons are molecules that contain only hydrogen and carbon. Alkanes are compounds of hydrogen and carbon which contain only single bonds. When the carbon atoms form a ring, the compounds are called cycloalkanes. Alkenes are hydrocarbons containing one or more C-C double bonds while alkynes contain one or more C-C triple bonds: Benzene, C6H6, and its derivatives are examples of the class of organic compounds called aromatic: Many functional groups contain polar bonds Haloalkanes have already been introduced. Alcohols (C-O-H) and ethers (C-O-C) can be converted into a large variety of other functionalities: The carbonyl functionality, C=O, is found in aldehydes, ketones, and carboxylic acids: Alkyl nitrogen and sulfur compounds are named amines and thiols: R represents a part of an alkane molecule in the following common functional groups: