Question

identify the charge of the ions in each compound, then type the formula below:
na po4
sodium phosphate
ca so4
calcium sulfate
(type final formula)
(type final formula)
answer key
3+
2+
1+
3-
2-
1-

Explanation:

Step1: Determine ion charges

• Sodium (\(Na\)) is in Group 1 of the periodic table, so it has a charge of \(1+\).
• Phosphate (\(PO_4\)) is a polyatomic ion with a charge of \(3-\).
• Calcium (\(Ca\)) is in Group 2 of the periodic table, so it has a charge of \(2+\).
• Sulfate (\(SO_4\)) is a polyatomic ion with a charge of \(2-\).

Step2: Use the criss - cross method to find the formula

• For sodium phosphate (\(Na\) and \(PO_4\)):
• The charge of \(Na\) is \(1+\) and the charge of \(PO_4\) is \(3-\).
• Using the criss - cross method (swap the absolute values of the charges as subscripts), we get \(Na_3PO_4\).
• For calcium sulfate (\(Ca\) and \(SO_4\)):
• The charge of \(Ca\) is \(2+\) and the charge of \(SO_4\) is \(2-\).
• Using the criss - cross method (swap the absolute values of the charges as subscripts, and since \(2/2 = 1\)), we get \(CaSO_4\).

Answer:

• For \(Na\): \(1+\)
• For \(PO_4\): \(3-\)
• Formula for sodium phosphate: \(Na_3PO_4\)
• For \(Ca\): \(2+\)
• For \(SO_4\): \(2-\)
• Formula for calcium sulfate: \(CaSO_4\)