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PART - 1 CH - 3 Classification of Elements and Periodicity in Properties — Chemistry STD 11 Science — Question

Rajasthan BoardEnglish MediumSTD 11 ScienceChemistryPART - 1 CH - 3 Classification of Elements and Periodicity in Properties2 Marks
Question
How do atomic radius vary in period and in group? How do you explain the variation?
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Answer

Atomic radius increases an moving from top to bottom in a group because as the value of principal quantum number (n) increases, new shells are added. Therefore, the valence electrons move away from the nucleus because internal energy levels remain filled with electrons, due to which shielding effect the nuclear force of attraction reduces.
Atomic radius decreases while moving from left to right in period because the shell remains the same and electrons keep filling in the same shell but the nuclear charge increases due to which the force of nuclear attraction increases.

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