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Lesson 18: Energy Changes in Physical Changes Heating and cooling Energy absorbed and released Changes of state (link back to C1)
Year 8 • Chemistry
Energy Changes in Physical Changes
In this lesson, students explore how energy changes during physical changes, understand heating and cooling, and learn when energy is absorbed or released during changes of state using the particle model.
Lesson Objectives
- Understand energy changes during physical changes.
- Describe heating and cooling.
- Explain when energy is absorbed or released.
- Link changes of state to the particle model.
1. Energy and Physical Changes
During a physical change, substances do not change chemically, but energy is transferred.
Energy changes affect how particles move.
[ Image Placeholder – Energy Transfer Diagram ]
Key idea:
• Physical changes involve energy changes
• Particles gain or lose energy
• Physical changes involve energy changes
• Particles gain or lose energy
2. Heating and Cooling
Heating adds energy to a substance.
Cooling removes energy from a substance.
[ Image Placeholder – Heating vs Cooling ]
• Heating → particles move faster
• Cooling → particles move slower
• Cooling → particles move slower
Example:
Ice melts when heated because particles gain energy.
3. Energy Absorbed and Released
Energy can be either absorbed or released during physical changes.
[ Image Placeholder – Energy Absorbed vs Released ]
Energy absorbed:
• Melting
• Evaporation
• Melting
• Evaporation
Energy released:
• Freezing
• Condensation
4. Changes of State (Link to C1)
Changes of state happen because of energy changes and particle movement.
This links directly to the particle model (C1).
[ Image Placeholder – Particle Model of States ]
• Solid → Liquid → Gas (energy absorbed)
• Gas → Liquid → Solid (energy released)
• Gas → Liquid → Solid (energy released)
Practice Questions
A. Fill in the Blanks
- Heating __________ energy to particles.
- Cooling __________ energy from particles.
- Melting requires energy to be __________.
- Freezing __________ energy.
- Physical changes involve __________ changes.
B. True or False
- Energy changes happen during physical changes.
- Particles move faster when cooled.
- Evaporation absorbs energy.
- Condensation releases energy.
- Changes of state are chemical changes.
C. Short Answer
- What happens to particle movement when a substance is heated?
- Name one change where energy is absorbed.
- Name one change where energy is released.
- How does this link to the particle model?
- Why does ice melt when heated?
✅ Show Answer Key
A. Fill in the Blanks
- adds
- removes
- absorbed
- releases
- energy
B. True or False
- True
- False
- True
- True
- False
C. Short Answer
- Particles move faster.
- Melting / evaporation.
- Freezing / condensation.
- Energy affects particle movement.
- Particles gain energy and break free.
© Aviate Learning – Energy Changes in Physical Changes (Year 8)
🔥❄️ Interactive Heating & Cooling Simulator
Use the buttons to add or remove energy.
Watch how particle motion and state change.
State: Solid | Energy: Low