Stuff and Substance | Teachers’ Guide | S3

TGB7: More ideas on temperature, holding power and energy

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1.	You might ask more able students to suggest whether holding power of particles is greater in P than in Q. Although the diagrams of P and Q do not show any clear difference in line thickness, students should use the fact that P shows particles in fixed patterns to suggest that the holding power must be greater in this case.
2.	Some students may suggest that the particles in snapshot Q must be more energetic than those in P because they aren’t held in place and have enough energy to break loose. Although this idea makes a lot of sense, it is better for them to focus on the idea that particles in snapshot Q aren’t held as strongly so they will be able to break free sooner – with less energy needed, at a lower temperature – than those in snapshot P.
3.	It is important to distinguish between the energy level of particles and the type of movement/freedom of movement they have. Students often think that the particles of ‘a liquid’ must have more energy than the particles of ‘a solid’, and that particles of ‘a gas’ must be even more energetic. This is only the case when we are comparing particles of the same substance in different states, however, and does not apply to different substances in different states: the particles of solid iron at 1000°C will be more energetic than those of oxygen at room temperature, for example.