Ionic Charges and Polyatomic Ions

The video tutorial explains how to write the formula for calcium oxalate. It begins by identifying calcium as a metal with a 2+ charge and oxalate as a polyatomic ion with a 2- charge. The tutorial emphasizes the importance of balancing these charges to form an ionic compound with a net charge of zero. The final formula for calcium oxalate is presented as CaC2O4.

What is the element symbol for calcium as found on the periodic table?

• Cu

• Ca

• C

• Cl

Which of the following is a polyatomic ion?

• Sodium

• Chloride

• Oxalate

• Calcium

What is the ionic charge of the oxalate ion?

• 3-

• 2-

• 2+

• 1+

How can you find the charge of the oxalate ion if you don't memorize it?

• By asking a friend

• By checking the periodic table

• By guessing

• By looking it up on a table of polyatomic ions

What is the ionic charge of calcium in the compound calcium oxalate?

• 0

• 3+

• 2+

• 1+

What is the net charge of the compound calcium oxalate?

• 1+

• 0

• 3+

• 2-