Inside the atom
Inside the atom

An atom has a tiny, dense nucleus at its centre. The nucleus contains protons and neutrons, while electrons occupy shells around the nucleus.
Step-by-step lessons on Edexcel GCSE Chemistry 2.1.2 Structure of the atom and subatomic particles. Each one builds up to exam-style questions. Nail the core quantitative topics — moles, balancing equations and calculations — early on, since they underpin higher-tier questions across every paper and topic.