Nucleophilic additions are chemical reactions where a nucleophile, a species with a high electron density, attacks an electrophile, which is electron-deficient. This process typically occurs in carbonyl compounds, such as aldehydes and ketones, where the carbon atom in the carbonyl group is positively polarized. The nucleophile donates its electrons to form a new bond, resulting in an intermediate compound. After the nucleophile adds to the carbonyl carbon, the intermediate can undergo further reactions, often leading to the formation of alcohols. This type of reaction is fundamental in organic chemistry and is widely used in the synthesis of various organic compounds.