Curriculum
Science — Second Preparatory
Unit 1: Matter and Energy
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Unit 2: Matter and Chemical Reactions
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Unit 3: Energy Flow in Photosynthesis and Respiration
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Unit 4: Geological Processes
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Text lesson
Changes of State
Changes of State
Matter changing from one state to another
Matter changing from one state to another
- The state of matter changes when it is heated or cooled, and its chemical composition stays the same.
- Liquid water, ice and water vapour are all made of the same water molecules, H₂O.
- What changes is the arrangement of the molecules, their movement and the forces between them.
- When a solid is heated, its particles gain kinetic energy, overcome the forces holding them together and move to another state.
- When matter is cooled, its particles lose energy, come closer together and become more firmly held.
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