"Reactions and Mechanisms" refers to the processes by which chemical substances transform into new products. A chemical reaction involves the breaking and forming of bonds between atoms, resulting in a change in the composition of the substances involved. Common types of reactions include synthesis, decomposition, and redox reactions. The mechanism of a reaction describes the step-by-step sequence of events at the molecular level. It explains how reactants are converted into products, detailing the intermediates and transition states involved. Understanding these mechanisms is crucial for fields like organic chemistry and biochemistry, as it helps predict reaction outcomes and develop new synthetic pathways.