Question

How do the acidities of the aqueous solutions of the alkaline earth metal ions (${\mathbf{M}}^{\mathbf{2}\mathbf{+}}$) change in going down the group?

Short answer

The acidities of an aqueous solution of alkaline earth metal decrease the group.

Step-by-step solution

Concept Introduction

The alkaline earth metals are a set of six chemical elements in the periodic table's group two. Beryllium, magnesium, calcium, strontium, barium, and radium are elements. At normal temperature and pressure, the elements have extremely similar properties.

Acidity in group

The acidic character of ions is directly related to the ability to attract electrons.

Hence, the higher the ability to attract the electrons, the greater the acidity.

The electronic configuration of alkaline earth metals is${\mathrm{ns}}^2$.

Alkaline earth metals lose two outermost electrons, form divalent cations,${\mathrm{M}}^{2+}$ and attain noble gas configuration.

Because of that, alkaline earth metals are highly electropositive. This property increases down the group because the distance from the nucleus and the valence shell increases, leading to a decrease in effective nuclear charge.

With a decrease in effective nuclear charge, the tendency to attract the electrons decreases down the group, and the acidities of the aqueous alkaline earth metal decrease.

Therefore, it is concluded the acidity increases down the group.