Groups and outer-shell electrons
Groups and outer-shell electrons

A group is a vertical column in the periodic table. Elements in the same main group have the same number of electrons in their outer shell, so they often have similar chemical properties.
Step-by-step lessons on Edexcel GCSE Chemistry 7.1.1 Classifying elements by group in the periodic table. 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.