Chapter U1.22, Problem 6E

Interpretation Introduction

Interpretation:

The charge on phosphate ion in ${\text{Ca}}_{\text{3}}{\left({\text{PO}}_{\text{4}}\right)}_{\text{2}}$ should be predicted.

Concept introduction:

An ionic compound is formed from a cation and an anion where cation has positive charge and anion has negative charge. The cation with positive charge is written first followed by the anion in the chemical formula of the ionic compounds.

Answer to Problem 6E

The charge on phosphate ion in ${\text{Ca}}_{\text{3}}{\left({\text{PO}}_{\text{4}}\right)}_{\text{2}}$ is -3.

Explanation of Solution

Calcium phosphate, ${\text{Ca}}_{\text{3}}{\left({\text{PO}}_{\text{4}}\right)}_{\text{2}}$ is an ionic compound. In the ionic compound, calcium is metal that belongs to group 2 in the periodic table thus, it has + 2 charge and phosphate is a polyatomic species.

To form a neutral ionic compound, the subscript of Ca represents the charge on phosphate ions and the subscript of phosphate ion represents the charge on calcium.

Thus, the charge on Ca is + 2. Similarly, the charge on phosphate ion would be -3.

Conclusion

Thus, the charge on phosphate ion in ${\text{Ca}}_{\text{3}}{\left({\text{PO}}_{\text{4}}\right)}_{\text{2}}$ is -3.