Here's how to figure that out:
* Calcium chloride: Calcium (Ca) has a +2 charge, and chloride (Cl) has a -1 charge. To balance the charges, you need two chloride ions for every calcium ion.
* Sodium carbonate: Sodium (Na) has a +1 charge, and carbonate (CO₃) has a -2 charge. To balance the charges, you need two sodium ions for every carbonate ion.
Let me know if you need help with other chemical formulas!
