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Atomic StructureKey Facts

Electronic Configuration and the Periodic Table

Part of Electronic Configuration · GCSE GCSE Chemistry revision

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. Use this page as part of a wider topic revision path rather than treating it as an isolated fact. 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.

Keep building this topic

Read this section alongside the surrounding pages in Electronic Configuration. That gives you the full topic sequence instead of a single isolated revision point.

The Shell RulesWorked Examples: Writing Electronic ConfigurationsThe Atom's Address SystemElectron Shells and Electronic Configuration

Practice Questions for Electronic Configuration

What is the maximum number of electrons the first electron shell can hold?

  • A. 2
  • B. 8
  • C. 18
  • D. 1
1 markfoundation

Explain why noble gases are unreactive.

2 marksstandard

Quick Recall Flashcards

What does the group number tell you?
The number of electrons in the outer shell
Which shell do electrons fill first?
The innermost shell (closest to the nucleus)

24 questions on Electronic Configuration — practise free

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The Shell Rules

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Worked Examples: Writing Electronic Configurations