| Lesson Plan |
| Grade: |
Date: 25/02/2026 |
| Subject: Physics |
| Lesson Topic: understand that isotopes are forms of the same element with different numbers of neutrons in their nuclei |
Learning Objective/s:
- Describe the relationship between atomic number, mass number, and neutron number.
- Explain why isotopes of the same element have identical chemical properties but may differ in stability.
- Calculate the number of neutrons in a given isotope using N = A − Z.
- Interpret isotope notation and distinguish stable from radioactive isotopes.
- Apply knowledge of isotopes to real‑world contexts such as radiocarbon dating and nuclear medicine.
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Materials Needed:
- Projector or interactive whiteboard
- Slide deck on isotopes
- Periodic‑table handouts
- Worksheet with isotope notation and calculation problems
- Sample isotope data sheet (e.g., C‑12, C‑14, U‑235)
- Exit‑ticket cards
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Introduction:
Begin with a quick poll: “What makes two atoms of the same element different?” Connect this to prior learning about protons and atomic number, then state that today students will discover how varying neutron numbers create isotopes. Success criteria: students will read isotope notation, compute neutron counts, and explain stability differences.
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Lesson Structure:
- Do‑now (5 min): Students answer the poll question on index cards; teacher notes misconceptions.
- Mini‑lecture (10 min): Present isotope notation, Z, A, N definitions with slide examples (C‑12, C‑14).
- Guided practice (10 min): Worksheet calculations of neutron numbers for several isotopes.
- Group activity (12 min): Using periodic tables, groups list natural isotopes of a chosen element and discuss stability.
- Real‑world applications (8 min): Brief case studies on carbon dating and PET scans; identify the isotopes used.
- Check for understanding (5 min): Quick quiz via Kahoot or show of hands.
- Exit ticket (5 min): Write one stable and one radioactive isotope and explain the difference.
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Conclusion:
Summarise that isotopes share the same proton count but differ in neutron number, affecting mass and stability. Review a few exit‑ticket responses as retrieval practice. For homework, students will calculate the average atomic mass of chlorine using provided isotopic abundances.
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