HESI A2 Chemistry Practice Exam – Prep, Study Guide & Practice Questions

Thermal energy is defined as the total kinetic energy of the particles in a substance. This concept arises from the notion that the temperature of a material is a measure of the average kinetic energy of its particles. As particles move faster, the thermal energy increases, leading to a rise in temperature. This kinetic energy arises from the constant motion of atoms and molecules within a substance, whether they are vibrating in place (in solids), moving past each other (in liquids), or moving freely (in gases).

While other forms of energy, such as chemical energy and gravitational potential energy, can also influence the behavior of matter, they do not define thermal energy itself. Therefore, recognizing thermal energy specifically relates to the motion of particles helps in understanding various physical phenomena, such as heat transfer and the behavior of substances at different temperatures.