2.2 Electronic Structure and Periodicity: Can we predict how elements behave?
Use electronic structure and periodic position to predict group properties and reactivity.
How to study WJEC GCSE The Sciences
Move from a scientific model to a prediction or method, collect or interpret evidence, show quantitative working and finish with a conclusion whose limits match the data.
Core concepts
Concept 1
Link atomic number and electron arrangement to period and group.
Exam cue: Identify the unit, entered tier, supplied reference material, command word and relevant scientific enquiry skill.
Concept 2
Predict ion formation and reactivity from outer electrons.
Exam cue: Use the final shell and movement of electrons to justify the predicted ion, group trend or displacement.
Concept 3
Compare trends and reactions in Groups 1 and 7.
Exam cue: Use scientific terminology, show quantitative working with units, and connect conclusions to data and the stated model.
Concept 4
Official subtopics: 2.2.1 The periodic table; 2.2.2 Electronic structure and reactivity; 2.2.3 Group 1 and group 7.
Concept 5
Scientific enquiry and mathematical skills apply in this topic; bold amplification is Higher Tier only.
Risk pitfalls and guardrails
Describing a periodic trend without linking it to electronic structure.
Guardrail: Do not import outgoing 3430QD content, another science route, a fixed required-practical list or unsupported tier and connection assumptions.
Recalling a fact without applying it to the observation, data, practical method or unfamiliar context.
Guardrail: Use the live secure pack: Task A may use groups of up to three; Task B is individual and highly controlled. Two enquiries are selected by the centre from three.
Importing content, required practicals, tier rules or paper structure from the outgoing WJEC or another awarding-body route.
Guardrail: Bold amplification is Higher-only. Units 1-6 may mix tiers, but Unit 7 is untiered.
Memory anchors
Period
A horizontal row whose elements have the same number of occupied shells.
Group
A vertical column whose elements have related outer-electron structures.
Ion
A charged particle formed by loss or gain of electrons.
Group 1
Reactive metals with one outer electron that form positive ions.
Group 7
Reactive non-metals with seven outer electrons that form negative ions.
Checkpoint rule
Do the check-up only after you can summarize each concept in one sentence and identify one dangerous pitfall from memory.
Knowledge Check (after reading)
Short check-up to confirm understanding of this module.
Check-up Questions
What does a period number show for a main-group atom? Justify the prediction from outer electrons and position in the periodic table. Check that the proposed mechanism conserves the relevant quantity.
Why do Group 1 metals form 1+ ions? Justify the prediction from outer electrons and position in the periodic table. Use only the measurements stated in the stem.
Answer all questions to submit.
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Move forward only after this module is stable.
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