Atomic StructureTopic Summary
Knowledge Organiser: Electronic Configuration
Part of Electronic Configuration · GCSE GCSE Chemistry revision
This topic summary covers Knowledge Organiser: Electronic Configuration 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 12 of 12 in this topic. Use this topic summary to connect the idea to the wider topic before moving on to questions and flashcards.
Topic position
Section 12 of 12
Practice
24 questions
Recall
24 flashcards
Knowledge Organiser: Electronic Configuration
Key Terms
- Shell: Energy level where electrons are found
- Configuration: Arrangement written as e.g. 2,8,1
- Outer shell electrons: Determine chemical properties
- Group: = number of outer electrons
- Period: = number of occupied shells
Must-Know Facts
- Shell capacities: 1st = 2, 2nd = 8, 3rd = 8
- Electrons fill lowest energy shell first
- Same group = same outer electrons = similar properties
- Full outer shell = stable = unreactive (Group 0)
- Group 1: 1 outer electron, very reactive
- Group 7: 7 outer electrons, very reactive
Key Equations
- Group number = number of outer shell electrons
- Period number = number of occupied electron shells
- Total electrons = atomic number (for neutral atoms)
Common Mistakes
- Writing 2,8,3 for aluminium (Al, Z=13): Correct — but students often put all 13 in one shell; remember 2 + 8 + 3
- Mixing up group and period: Group = column (outer electrons); Period = row (number of shells)
- Saying 3rd shell holds 18 electrons: At GCSE the 3rd shell holds maximum 8 electrons
- Configuration doesn't determine reactivity: It does — number of outer electrons directly determines how reactive the element is