This comprehensive OCR A Level Chemistry PowerPoint lesson introduces electron shells, sub-shells and atomic orbitals through clear explanations, diagrams, worked examples and practice activities.

Designed for OCR Chemistry A (H032/H432), Module 2: Foundations in Chemistry, this resource covers specification points 2.2.1(a) and 2.2.1(b) – Electron Structure. It is ideal for Year 12 students developing their understanding of atomic structure and the arrangement of electrons within atoms.

The lesson introduces electron shells as energy levels surrounding the nucleus, explaining the principal quantum number and the maximum number of electrons that can occupy each of the first four shells. Students progress from the simplified GCSE model of electron arrangements to a more detailed understanding of sub-shells and atomic orbitals.

An atomic orbital is introduced as a region around the nucleus that can hold a maximum of two electrons with opposite spins. The PowerPoint explores the shapes of s-orbitals (spherical) and p-orbitals (dumbbell-shaped), alongside the number of orbitals and maximum electron capacities of s-, p- and d-sub-shells.

Students learn how shells, sub-shells and orbitals relate to one another, including how their individual electron capacities determine the maximum number of electrons within a shell. Electron spin and the requirement for paired electrons to have opposite spins are also explained.

The resource includes a starter activity, key terminology, detailed diagrams, structured practice activities, knowledge checks and answers to support assessment for learning.

Supplied as an editable PowerPoint presentation (.pptx), this resource is suitable for classroom teaching, revision and consolidation of fundamental atomic structure concepts.

Last updated: November 2026.