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when heat is added to a substance, describe how the molecules are affected. enter your answer in the space provided.

Here is the kinetic theory of matter: All matter is made up of atoms and molecules that are constantly moving. When heat is added to a substance, the molecules and atoms vibrate faster. As atoms vibrate faster, the space between atoms increases. They contract when they lose their heat.

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When heat is added to a substance, the molecules vibrate faster. The space in between molecules increases as molecules vibrate faster. The increased spacing causes the substance to expand. Depending on the state of the substance, whether it is a solid or liquid, if enough heat is added, the increased vibration and spacing will lead to a change in state - from solid to liquid or from liquid to gas.