The shape and polarity of a molecule determines how it will react with other molecules. The physical state of a substance is determined by the forces that hold individual molecules together as a group. This is what determines whether a substance is a solid, a liquid, or a gas. It also determines how much energy is needed to do various things like melting, freezing, boiling, and condensing. The image on this page shows that water can exist in three different states. Water is ice as a solid, water as a liquid, and vapor as a gas. What happens to the intermolecular forces as water changes states? In this topic, you will investigate these molecular forces.
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