The Development of the Atomic Model

This lesson covers the historical development of the atomic model as required by the AQA GCSE Physics specification (4.4.1). You need to understand how scientific ideas about the atom changed over time as new experimental evidence was discovered, and why each model was replaced by a better one.

---

Why Models Change in Science

A model in science is a simplified representation of something complex. Models are useful because they help us understand and predict the behaviour of things we cannot directly observe — like atoms.

Scientific models are not fixed — they change over time when new evidence is discovered that the existing model cannot explain. Each new model must:

• Explain all the evidence that the previous model explained.
• Also explain the new evidence that the previous model could not.

The history of the atomic model is an excellent example of how science progresses through evidence and peer review.