Question

Why is the ionic radius of sodium far smaller than its atomic radius?

Answer 1

Ions can be both positively charged or negatively charged. I assume that by ‘ion’ u mean the positively charged species. These ions, called cations are formed when electrons from the outermost shell are taken away. This results in less repulsion between the other electrons and thus the effective nuclear charge becomes greater, which holds the outer electrons with greater force, reducing the atomic size