1. Energy is the capacity to do work or produce a change. Think of the energy of a substance as the total of the kinetic & potential energies of all the particles present.

2. Temperature is a measure of the average kinetic energy of the particles. Temperature does not depend on the number of particles present, only the average kinetic energy of those particles. Heat is the energy that is transferred from one object to another because of a difference in their temperatures.

3. A hot substance (high temp.) has particles with high average kinetic energy and a cool substance (low temp.) has particles with lower average kinetic energy. When the substances come into contact, the particles collide with each other. During these collisions, some energy is transferred from higher energy particles to lower energy particles. This transfer of energy is called heat. As the collisions continue, the particles of both substances will eventually have the same average kinetic energies. This is when the substances have the same temperature.

4. 1. All matter is made up of tiny particles (atoms, molecules, or ions) 2. These particles are in continuous motion. 3. Particles exert forces of attraction on one another. 4. The higher the temperature, the greater the kinetic energy of the particles.