| Lesson Plan |
| Grade: |
Date: 25/02/2026 |
| Subject: Physics |
| Lesson Topic: Describe how the scattering of alpha (α) particles by a sheet of thin metal supports the nuclear model of the atom, by providing evidence for: (a) a very small nucleus surrounded by mostly empty space (b) a nucleus containing most of the mass of the |
Learning Objective/s:
- Describe how Rutherford’s gold‑foil experiment provides evidence for a tiny, dense nucleus.
- Explain why most of an atom’s volume is empty space.
- Identify the positive charge of the nucleus based on α‑particle deflection.
- Interpret scattering data to differentiate small‑angle and large‑angle events.
- Apply the Rutherford scattering concept qualitatively to predict scattering behaviour.
|
Materials Needed:
- Projector and screen for diagrams
- Whiteboard and markers
- Printed worksheet with observation tables
- PowerPoint slides summarising the experiment
- PhET simulation of α‑particle scattering
- Exit‑ticket cards
|
Introduction:
Begin with a striking image of a beam of particles hitting a thin foil to capture interest. Prompt students to recall previous atomic models and ask what they would expect if atoms were solid. State that by the end of the lesson they will be able to explain how the experiment proves a tiny, massive, positively‑charged nucleus and a mostly empty atom.
|
Lesson Structure:
- Do‑now (5') – Quick quiz on atomic models; students note one fact about Rutherford’s experiment.
- Mini‑lecture (10') – Present background, show schematic of the gold‑foil setup and key observations.
- Data analysis activity (15') – In groups, examine the observation table, fill in the “Evidence” column, and discuss what each observation reveals.
- Simulation demonstration (5') – Run the PhET α‑particle scattering simulation; observe trajectories and angles.
- Guided reasoning (10') – Whole‑class discussion linking observations to (a) empty space, (b) massive nucleus, (c) positive charge.
- Worksheet practice (10') – Short questions requiring students to describe why a few particles are deflected sharply and relate it to nuclear mass.
- Check for understanding (5') – Exit ticket: one sentence summarising how the experiment supports the nuclear model.
|
Conclusion:
Recap the three pieces of evidence and emphasise how they collectively overturn the plum‑pudding model. Collect exit tickets to gauge retention and assign a brief homework: write a paragraph comparing the Rutherford model with the modern quantum model.
|