Electronic Configuration and the Periodic Table
Part of Electronic Configuration — GCSE Chemistry
This key facts covers Electronic Configuration and the Periodic Table 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 5 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 5 of 12
Practice
24 questions
Recall
24 flashcards
🔗 Electronic Configuration and the Periodic Table
This is where it all connects!
- Group number = Number of electrons in the outer shell
- Period number = Number of occupied shells
Examples:
- Sodium (Na) — Configuration: 2,8,1 → Group 1 (1 outer electron), Period 3 (3 shells)
- Chlorine (Cl) — Configuration: 2,8,7 → Group 7 (7 outer electrons), Period 3 (3 shells)
- Carbon (C) — Configuration: 2,4 → Group 4 (4 outer electrons), Period 2 (2 shells)
- Neon (Ne) — Configuration: 2,8 → Group 0 (full outer shell), Period 2 (2 shells)
Why outer electrons matter:
- Atoms with the same number of outer electrons have similar chemical properties
- This is why elements in the same group behave similarly!
- Atoms with full outer shells are very stable and unreactive (noble gases)
Quick Check: Chlorine has atomic number 17. Write its electronic configuration and state which group and period it belongs to.
Configuration: 2,8,7. Group 7 (7 outer electrons). Period 3 (3 occupied shells).