The Development of the Atomic Model

This lesson covers the history of the atomic model and how our understanding of the atom has changed over time — as required by the Edexcel GCSE Chemistry specification (1CH0), Topic 1: Key Concepts in Chemistry. You need to understand how scientific models develop when new experimental evidence is found, and be able to describe the key models in the history of atomic theory.

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Why Do Scientific Models Change?

A model in science is a simplified representation of something that helps us explain observations and make predictions. Scientific models are not permanent — they change when new experimental evidence is discovered that the current model cannot explain.

Key principles:

• Models are based on the best evidence available at the time.
• When new evidence contradicts the current model, scientists must modify or replace it.
• The development of the atomic model is an excellent example of how science progresses through evidence and peer review.