What defines thermal energy?

Thermal energy is defined as the total energy of the particles in a substance related to its temperature. This concept arises from the idea that the particles (atoms and molecules) within any given material are in constant motion, and their kinetic energy contributes to the overall thermal energy. As the temperature of a substance increases, the motion of its particles also increases, resulting in a higher thermal energy state.

This definition highlights the relationship between thermal energy and temperature, demonstrating that temperature is a measure of the average kinetic energy of the particles. The more energetic the particles are, the higher the temperature and the greater the thermal energy.

In contrast, the other choices do not accurately capture the essence of thermal energy. The energy of an object due to its internal structure pertains more to potential energy related to the arrangement of particles, rather than their movement. Energy resulting from mechanical work focuses on forces acting through distances, which is separate from the particle motion that defines thermal energy. Lastly, while energy associated with chemical bonds involves interactions between atoms within molecules, it is not synonymous with thermal energy, which is specific to the kinetic energy of particles in motion.