Chapter EH, Problem 14R

Solution

Interpretation: The charge on alkaline earth metal ions needs to be explained.

Concept Introduction: Atom of an element can lose or gain electron/s to form ions. Here, metals tend to lose electron/s to form positive charge ions or cations and non-metals tend to gain electron/s to form negative charge ions or anions. The charge on an ion is equal to the number of electrons lost or gained.

+2

In the periodic table, alkaline earth metal belongs to group 2. Thus, the number of the valence electron in their valence shell is 2.

Metals tend to lose electrons to form positive charge ions or cations. Since alkaline earth metals have 2 valence electrons, they can lose 2 electrons to attain noble gas electron configuration or to complete their octet.

The charge on an ion depends on the number of electrons lost or gained. If electron/s are lost, the ion will have a positive charge; thus, the charge on alkaline earth metal ions is +2.

Some examples of alkaline earth metal ions are ${\text{Mg}}^{2+}$ , ${\text{Ca}}^{2+}$ , ${\text{Ba}}^{2+}$ , etc.

The charge on alkaline earth metal ions is +2.