Worked Examples: Writing Electronic Configurations
Part of Electronic Configuration · GCSE GCSE Chemistry revision
This worked example covers Worked Examples: Writing Electronic Configurations 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 6 of 12 in this topic. Treat this as a marking guide for what examiners are looking for, not just a fact list.
Topic position
Section 6 of 12
Practice
24 questions
Recall
24 flashcards
🧮 Worked Examples: Writing Electronic Configurations
Example 1: Magnesium (Mg) — Atomic number 12
→ Fill 1st shell: 2 electrons (remaining: 10)
→ Fill 2nd shell: 8 electrons (remaining: 2)
→ Fill 3rd shell: 2 electrons
Configuration: 2,8,2
Example 2: Oxygen (O) — Atomic number 8
→ Fill 1st shell: 2 electrons (remaining: 6)
→ Fill 2nd shell: 6 electrons
Configuration: 2,6
Example 3: Potassium (K) — Atomic number 19
→ Fill 1st shell: 2 electrons (remaining: 17)
→ Fill 2nd shell: 8 electrons (remaining: 9)
→ Fill 3rd shell: 8 electrons (remaining: 1)
→ Fill 4th shell: 1 electron
Configuration: 2,8,8,1
Quick Check: An element has electronic configuration 2,8,3. Which group and period is it in, and what is its atomic number?
Group 3 (3 outer electrons), Period 3 (3 shells). Atomic number = 2 + 8 + 3 = 13 (this is aluminium, Al).
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.
Practice Questions for Electronic Configuration
What is the maximum number of electrons the first electron shell can hold?
Explain why noble gases are unreactive.
Quick Recall Flashcards
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