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1.1.7 Electronic structure
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Shells and energy levels

Shells and energy levels

Simplified shell model for the first 20 elements, with shells labelled n=1, n=2, and n=3

Electrons occupy orbitals in subshells. They fill the lowest-energy available subshells first. Shell number describes the main energy level and distance scale from the nucleus, but shell distance does not universally determine orbital energy because subshell energies can cross.

1.1.7 Electronic structure Lesson

  1. GCSE
  2. /Chemistry
  3. /1.1.7 Electronic structure

Step-by-step lessons on AQA GCSE Chemistry 1.1.7 Electronic structure. 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.

Lessons