This document provides an overview of thermochemistry and nuclear chemistry concepts. It defines different types of energy, including radiant, thermal, chemical, and potential energy. The first law of thermodynamics states that energy cannot be created or destroyed, only converted from one form to another. Chemical reactions can be exothermic or endothermic depending on whether energy is released or absorbed. Enthalpy changes (ΔH) are used to quantify energy changes in chemical and physical processes. The document also discusses thermochemical concepts like heat, work, state functions, and calorimetry which involve measuring energy changes during physical and chemical changes.