This document discusses nucleophilic addition reactions to carbonyl compounds. It defines nucleophiles as electron rich species that donate electron pairs to form bonds. Strong nucleophiles like hydroxide are discussed along with examples of nucleophilic addition including addition of water, alcohols, hydrogen cyanide, organometallic reagents, and ammonia derivatives to carbonyl groups. The mechanism of nucleophilic addition is described as the nucleophile attacking the carbonyl carbon to form a tetrahedral intermediate that then collapses to form the alcohol, hydrate, imine or other product.