This key facts covers The Shell Rules within Electronic Configuration for GCSE Chemistry. Revise Electronic Configuration in Atomic Structure for GCSE Chemistry with 24 exam-style questions and 24 flashcards. This topic appears less often, but it can still be a useful differentiator on mixed-topic papers. It is section 4 of 12 in this topic. Use this key facts to connect the idea to the wider topic before moving on to questions and flashcards.
Topic position
Section 4 of 12
Practice
24 questions
Recall
24 flashcards
📌 The Shell Rules
Electrons are arranged in shells around the nucleus:
- 1st shell (closest to nucleus) — holds maximum 2 electrons
- 2nd shell — holds maximum 8 electrons
- 3rd shell — holds maximum 8 electrons (at GCSE level)
Filling order:
- Electrons always fill the lowest energy shell first (closest to nucleus)
- Only when a shell is full do electrons move to the next shell
- This is why electronic configuration follows predictable patterns!
Writing electronic configuration: Numbers separated by commas, e.g., 2,8,1 means 2 electrons in shell 1, 8 in shell 2, 1 in shell 3.