Chemical energy is the potential energy stored within the chemical bonds between atoms in molecules. When chemical reactions occur, these bonds are broken and new bonds are formed, releasing or absorbing energy. Nuclear energy is stored within the nucleus of an atom, in the forces holding protons and neutrons together. Potential energy is stored energy based on position or state (e.g., gravitational potential energy, elastic potential energy). Thermal energy is energy associated with the temperature of an object due to the kinetic energy of its atoms and molecules.