S3.5.3 For the adult
Changes of state
Why does ice melt on a hot day, and steam turn to drops on a cold lid?
What this chapter teaches
Heat gives particles energy, and cooling takes it away. At the melting point a solid melts, and at the boiling point a liquid boils. Melting and boiling points tell you the state of a material at any temperature.
Three questions to ask
There is no one right wording. Listen for the idea.
- What do you think happens to the particles of ice as it melts?
- How is boiling different from water drying in the sun?
- Is iron a solid, a liquid or a gas in this room, and how could you work it out?
After the chapter, the learner can
- Explain melting, boiling and condensing as particles gain or lose energy
- Use melting and boiling points to find the state at room temperature
What they copy into their notebook
Heat gives particles energy. At the melting point a solid melts. At the boiling point a liquid boils. Cooling takes energy away: gas condenses, liquid freezes.