atomic radius trend

Question

Which order correctly represents increasing atomic radius (period 2 elements)?

RankGuru · Accepted Answer

1. **Trend across a Period**: Atomic radius decreases from left to right as you move across a period.
2. **Reason**: The nuclear charge ($Z$) increases by one unit for each element, pulling the electrons in the same main shell closer to the nucleus. Shielding by inner electrons remains constant.
3. **Positions in Period 2**: The elements are Carbon ($Z=6$), Nitrogen ($Z=7$), Oxygen ($Z=8$), and Fluorine ($Z=9$).
4. **Relative Sizes**: Fluorine is the furthest right and thus the smallest. Carbon is the furthest left and thus the largest.
5. **Correct Order**: Increasing radius means **Smallest → Largest**: **$F < O < N < C$**.

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atomic radius trend

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