Question

write the charge of each ion in the compound below.
calcium phosphate
calcium = phosphate =
write the formula for the compound below. be sure to include the subscripts, for example: if your answer was cucl₂, you would select cucl2

Explanation:

Step1: Determine the charge of calcium ion

Calcium is in group 2 of the periodic table. Elements in group 2 tend to lose 2 electrons to form cations. So, the charge of calcium ion ($Ca^{2+}$) is $+2$.

Step2: Determine the charge of phosphate ion

Phosphate ion ($PO_{4}^{3 - }$) is a poly - atomic ion. By common knowledge of poly - atomic ions, the charge of phosphate ion is $- 3$.

Step3: Write the formula of calcium phosphate

To form a neutral compound, we use the criss - cross method. The charge of calcium ($+2$) becomes the subscript of phosphate, and the charge of phosphate ($-3$) becomes the subscript of calcium. So the formula is $Ca_{3}(PO_{4})_{2}$.

Answer:

Calcium = $+2$; Phosphate = $-3$; Formula = $Ca_{3}(PO_{4})_{2}$