[ Visit http://www.wewwchemistry.com ] This is a summary of reactions involving hydrocarbons, prepared according to the Singapore-Cambridge GCE A Level 9647 H2 Chemistry syllabus. Free-radical substitution mechanism of alkanes, electrophilic addition of alkenes and electrophilic (aromatic) substitution of arenes are covered. A brief discussion on the aromaticity of the benzene ring, and examples of activating and deactivating substituent groups are also included.