Magnesium Phosphate and Polyatomic Ions

The video tutorial explains how to write the formula for magnesium phosphate. It begins by identifying magnesium and phosphate, noting that phosphate is a polyatomic ion. The tutorial discusses the ionic charges of magnesium and phosphate, emphasizing the need for these charges to balance to zero. The crisscross method is introduced to adjust subscripts and balance the charges. The tutorial concludes by verifying the formula and ensuring the net charge is zero, resulting in the correct formula: Mg3(PO4)2.

What is the element symbol for magnesium?

• Mg

• Mo

• Ma

• Mn

Which of the following is a polyatomic ion?

• Mg

• O2

• PO4

• Cl

What type of compound is formed when a metal and nonmetals combine?

• Molecular

• Metallic

• Ionic

• Covalent

What is the ionic charge of magnesium in group two of the periodic table?

• 2+

• 1+

• 4+

• 3+

What is the charge of the phosphate ion?

• 4-

• 1-

• 2-

• 3-

What method is used to balance the charges in magnesium phosphate?

• Substitution

• Cross-multiplication

• Addition

• Crisscross

Why do we use parentheses around the phosphate ion in the formula?

• To separate it from magnesium

• To balance the equation

• To show it is a polyatomic ion

• To indicate it is a metal

How many phosphate ions are needed to balance with three magnesium ions?

• Three

• Two

• One

• Four

What is the final formula for magnesium phosphate?

• MgPO4

• Mg2(PO4)3

• Mg3(PO4)2

• Mg(PO4)2