| Lesson Plan |
| Grade: |
Date: 25/02/2026 |
| Subject: Chemistry |
| Lesson Topic: Describe the properties of ionic compounds: (a) high melting points and boiling points (b) good electrical conductivity when aqueous or molten and poor when solid |
Learning Objective/s:
- Describe why ionic compounds have high melting and boiling points.
- Explain how ionic charge, size and lattice structure influence those temperatures.
- Compare electrical conductivity of ionic compounds in solid, molten and aqueous states.
- Predict the conductivity change when an ionic solid is melted or dissolved.
- Apply the concepts to a familiar example such as sodium chloride.
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Materials Needed:
- Projector or interactive whiteboard
- Slide deck on ionic lattices and conductivity
- Sample of table salt (NaCl) and a beaker of water
- Thermometer or temperature data sheet
- Simple conductivity tester or circuit kit
- Student worksheet with checklist and exit‑ticket
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Introduction:
Begin with a quick “mystery solid” demonstration – a piece of salt that does not light a bulb. Ask learners what they know about why some solids melt at very high temperatures and why some conduct electricity only when dissolved. State that today they will uncover the lattice reasons behind these behaviours and the criteria for success: being able to explain both melting‑point trends and conductivity changes.
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Lesson Structure:
- Do‑Now (5'): Students list examples of everyday ionic compounds and guess their melting points.
- Mini‑lecture (10'): Explain ionic lattices, charge magnitude, ionic radii and how they create strong electrostatic forces.
- Guided analysis (10'): Use the NaCl example – show melting/boiling data and discuss why the lattice is strong.
- Interactive demo (10'): Melt a small amount of salt (or use a simulation) and test conductivity in solid, molten, and aqueous states.
- Collaborative worksheet (10'): Groups fill a table comparing states, ion mobility, and conductivity; include a short “why” explanation.
- Check for understanding (5'): Quick “thumbs up/down” quiz on key factors affecting melting points.
- Wrap‑up discussion (5'): Highlight how charge and size modify lattice energy.
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Conclusion:
Recap the two hallmark properties of ionic compounds and the lattice reasons behind them. Students complete an exit ticket by writing one sentence that links lattice strength to both high melting points and conductivity behaviour. Assign homework: a short research task to find another ionic compound, report its melting point, and predict its conductivity in solid, molten, and aqueous forms.
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