atomic radius
What atomic radius means in Chemistry A-Level, as defined for AQA, OCR.
Definitions of atomic radius
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Reference: AQA
Falls steadily across Na to Ar because the outer electrons are pulled in harder as nuclear charge rises with similar shielding.
Going down the group the atomic radius increases, so the outer shell is further from the nucleus and the attraction is weaker.
Decreases across Period 3 because nuclear charge increases while shielding remains similar, pulling the outer shell closer.
Falls across a period because nuclear charge rises while the outer electrons stay in the same shell.
Topics that use atomic radius
- Physical properties of Period 3 elements (AQA A-Level)
- Periodicity (OCR A-Level)
- The halogens (OCR A-Level)
Related terms
- Halogen displacement reactions
- Ammonia solubility as a confirmatory test
- Applying the sequence to specific elements
- Benefits versus risks
- Cations and delocalised electrons
- delocalised electrons
- Diatomic molecular structure of halogens
- Displacement reactions of halogens with halide ions
Using atomic radius in the exam
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