Quantum chemistry is a branch of chemistry that focuses on the application of quantum mechanics to explain the behavior of atoms and molecules. It provides a theoretical framework for understanding chemical bonding, molecular structure, and electronic interactions by describing the quantum states of systems at the atomic and subatomic level. Quantum chemistry uses mathematical models to calculate properties such as molecular energy levels, reaction rates, and spectroscopic transitions, thereby bridging the gap between classical chemistry and fundamental physics. This approach allows chemists to predict and analyze chemical phenomena with a high degree of accuracy, greatly enhancing our understanding of material properties and chemical reactions.