Question

potassium, lithium,sodium, berylium which of this atom has smallest atomic radius . why?

Answer 1

beryllium is small atomic radius

Answer 2

Beryllium has the smallest atomic radius.
Since we know that Sodium , Potassium and Lithium are in the same group that is first group and are all alkali metals but Beryllium is from second group and and is on the top of the second group. And , so hence across the period the atomic size decreases so Beryllium has the smallest atomic radius or size.

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