A Levels Chemistry (9701)•9701/12/M/J/22
Explanation
Periodic trends in period 3 elements
Steps:
- Identify positions: Na (group 1), Mg (group 2), Si (group 14) in period 3.
- Recall atomic radius trend: decreases left to right due to increasing effective nuclear charge.
- Recall electronegativity trend: increases left to right as atoms attract electrons more strongly.
- Plot relative values: Na (largest radius, lowest EN), Mg (medium), Si (smallest radius, highest EN), yielding inverse relationship.
Why A is correct:
- Matches Pauling electronegativity scale and atomic radius data, showing EN rising as radius falls across period 3.
Why the others are wrong:
- B: Incorrectly shows increasing radius with EN, reversing size trend.
- C: Depicts flat or non-inverse relation, ignoring both trends.
- D: Places Si with low EN, contradicting group trend.
Final answer: A
Topic: The Periodic Table: chemical periodicity
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