Use the periodic table to compare the sizes of ionic radii with the corresponding atomic radii or other ionic radii. Choose from smaller and larger in the blanks below: A sodium cation is than a sodium atom.

A sodium atom loses one electron to form a sodium cation (Na⁺). Losing an electron reduces electron–electron repulsion, and the remaining electrons are pulled more strongly toward the nucleus, so Na⁺ is smaller than a sodium atom. The correct choice is smaller.

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