Which of the following elements has the smallest ionic radius?

a. K

b. Li

c. O

d. S

Lithium

Explanation:

Lithium is an alkali metal. This means that lithium is expected to be a member of the group one elements on the periodic table.

The group one elements ionize by losing one electron. Hence, the form univalent positive ions after ionization.

Lithium has 3 electrons, 2 belonging to the k shell with the valence L having the other electron. Upon ionization, it forms the ion Li+.

This means it has lost the electron in the valence shell probably through an ionic transfer. This means the only electron it has is in the S shell, which is of a smaller size when compared to elements having multiple rings of shell.

It is expected that negative ions become larger when they ionize as they receive more electrons while that of metals I. e positive electrons shrink when they ionize as they are givers of electrons.