Chemistry · KS3 Y9 · Particles & States of Matter
Limits of the particle model
Limits of the particle modelFree4:18Heddy Score 3 of 7, below the standard
What you need to know
- Early ideas pictured matter as tiny particles that cannot be broken down, and Dalton described atoms as solid spheres.
- Thomson's discovery of electrons showed atoms are not solid spheres, leading to the plum pudding model.
- Rutherford's gold foil experiment, where some alpha particles bounced back, showed the positive charge sits in a tiny nucleus.
- Bohr placed electrons in shells, and later work found protons and neutrons, so each model was replaced when new evidence exposed its limits.
In this clip
Runs 4:18, from 0:03 to 4:21 of the full video.
Heddy ScoreSeven checks every clip must pass before students see it: trusted, on the map, accurate, focused, accessible, safe, and proven by students.3/7, Below the standard
See the seven stars
- Trusted source · passed. The creator's own upload, live and playable here.
- On the map · not judged yet. A teacher watched it: it mainly teaches this map topic.
- Spec-true · not judged yet. Accurate, and right for the current UK specification.
- Focused · passed. One idea, short enough to watch in one go.
- Accessible · passed. Good captions, clear sound and pictures.
- Safe for children · not judged yet. Right for 11 to 16 year olds, with no sales pitch.
- Proven · not judged yet. Earned from our students: they learn from it, find it helpful and watch it to the end.
Our students
Not enough students yet
Our own students' answers. These are what move ★7 Proven.On YouTube
How the Heddy Score works265K views · 2.72K likes · Cognito 1.37M subscribers
As reported by YouTube on 2026-11-01. Not part of the Heddy Score.Why we picked it
Shows clearly how the simple hard-sphere picture of particles was revised as experiments revealed its limits, a good way into why models are imperfect but useful.
Cognito on YouTubechecked 2026-10-22
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