What will be the correct order of sizes of C,NP,S? Shoud we solve by using the concept of shielding effect?

Dear student,

Atomic radii in general decreases left to right in a period and increases down the group.
Order of atomic radii is P >S > C > N.
Decrease in atomic radii on moving from C to N and P to S in a period is because as we move left to right in a period as the number of electron increases the number of protons in the nucleus also increases due to which the valance shell electron experience greater effective nuclear charge ; therefore more strongly pulled by the nucleus , thus decreasing their sizes. Shielding effect decreases in the order s > p > d orbital electrons. s orbital electrons have greater shielding effect on the nucleus. On moving left to right in a period shielding effect is operable but is same across a period, therefore here we consider only the increase in the effective nuclear charge experienced by the valance shell electrons.


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