Organic reactions, naming systems

An addition reaction involves the combination of two molecules to form a product containing atoms from both reactants. All addition reactions occur on unsaturated organic structures—namely, alkenes, alkynes, carbonyls, and arenes. Not surprisingly, three distinct mechanisms are observed—electrophilic, nucleophilic, and radical. In the electrophilic addition pathway, the unsaturated system acts as the nucleophile supplying electrons to the electrophilic reagent. The opposite is true in the nucleophilic pathway. In either of these two cases, simple electrostatic considerations assist in predicting what will occur. 

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