LuduminaAT-02 · AT-U1 · Planned
Evidence and the changing atomic model
Learning objectives
Use scattering evidence to explain replacement of plum-pudding model; sequence electron, nucleus, Bohr levels, proton and neutron developments.
8463 §§4.4.1.3 / 8464 §§6.4.1.3
DfE single-science pp.43–44 / Combined pp.35–36. Evidence checked 30 September–1 October 2026. Skills: WS1.1,1.2,1.6,3.6; MS2c,4a.
Needs firstAT-01
Explanation
The scattering pattern challenged a diffuse positive-charge model. Most particles passed through, supporting mostly empty space; a few strongly deflected, supporting a small dense positive nucleus. Models develop through evidence, comparison and review rather than one perfect picture.
Concepts, equations and units: Models predict observations; most alpha pass, few large deflections; nucleus tiny,dense,positive; Chadwick neutron evidence.
Prediction, demonstration and game exercise
Predict, observe, explain
Predict scattering patterns from two models then reveal an evidence histogram; explain revision and peer scrutiny.
Planned learner game exercise
Choose a model consistent with supplied trajectories and write a revision memo citing observations.
Independent practice
Interpret frequency table/histogram and produce a two-observation argument.
Original practice example · Shared
Why did rare large alpha deflections favour the nuclear model over plum pudding?
Show working and model answer
Working / reasoning
Concentrated positive charge and mass could strongly deflect a small fraction close to the nucleus; diffuse charge could not account for the pattern.
Answer
They supported a small dense positive nucleus, consistent with most alphas passing through.
Exit check and success criteria
Both key observations linked to nuclear structure and historical sequence broadly correct.
During practice, compare the prediction with evidence and give an error-specific prompt. The exit item uses a fresh context or fresh values, answered independently.
Misconceptions, practical links and mastery
Check these misconceptions
Most alpha particles hit nucleus; one diagram proves every model feature; Bohr/Chadwick experimental detail is required.
Practical preparation
No live radiation apparatus; historical-data simulation.
Virtual preparation and revision only. Required hands-on activities and school records remain separate.
Proposed mastery
0: not yet evidenced. 1: supported. 2: independent exit criteria met. 3: successful changed-context transfer. Advance at 2; revisit with fresh retrieval. These are not GCSE grades.