Select a substance such as iodine and explore how physical changes of state can be brought about by supplying heat energy to the substance. Observe what happens when heat energy is removed. Observe the changes of state at both the physical and particle levels. Explain the different properties of solids and gases in terms of their particle movement. This learning object is one in a series of three objects. The series is also packaged as a combined learning object.
Objective
1. Students explain that changes of state occur when heat energy is added to, or removed from, a substance.
2. Students identify that changes of state such as sublimation and reverse sublimation are reversible physical changes.
3. Students explain that iodine will directly change from solid to gas and vice versa.
4. Students describe the properties of solids and gases in terms of their particles. During a change of state the particles of a substance do not change but their movement and the way they are packed together does change.
