Which element's ionic radius is smaller than its atomic radius?
A. Neon.
B. Sulfur.
C. Sodium.
D. Nitrogen.
E. Argon.
Elements that lose electrons form positive ions that are smaller than atoms of the same element. Therefore the ionic radius of these ions is smaller than its atomic radius. Only choice c, sodium, is a metal that will lose electrons. Neon and argon are stable and will neither lose nor gain electrons. Nitrogen and sulfur will tend to gain electrons, each having a larger ionic radius than atomic radius.