What monatomic ions do potassium (Z = 19) and iodine (Z = 53) form?

Alkali metals are the metals present in Group . Using the periodic table, the elements in this group are lithium (Li), sodium (Na), potassium (K), rubidium (Rb), caesium (Cs), and francium (Fr). These electropositive metals lose one electron quickly (as there is only one electron in their valence shell and on losing this they achieve noble gas configuration) to generate monoatomic ions with a +1 charge on them. Hence, potassium produces a${\mathbf{K}}^{\mathbf{+}}$cation.

Theelements in Group (also called halogens) are nonmetals. The halogen elements on the modern periodic table are fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and astatine (At). They are electronegative in nature. So, these nonmetals gain one electron rapidly(as there are seven electrons in their valence shell and on accepting one electron from some metal they achieve noble gas configuration) to generate mono-anions with a -1 charge on them. Therefore, iodine produces a anion.