2. Step One Write the symbols for the elements in the compound. Ba Cl

3. Look up the oxidation numbers of the elements involved and write them as superscripts to the right of the elemental symbols. Ba 2+ Cl -

4. All net positive charges and negative charges must be equal. The net charge for the compound must equal zero. Ba Cl +2(1) + -1(2) = 0 BaCl 2

5. Practice Magnesium oxide Mg 2+ O 2- MgO +2(1) + -2(1) = 0

6. Practice Aluminum oxide Al 3+ O 2- Al 2 O 3 +3(2) + -2(3) = 0

7. Practice Lead (IV) sulfide Pb 4+ S 2- PbS 2 +4(1) + -2(2) = 0

8. Additional Practice 1.Lithium iodide 2.Cadmium hydride 3.Aluminum oxide 4.Iron (II) oxide

9. Additional Practice Answers 1.LiI 2.CdH 2 3. Al 2 O 3 4. FeO

11. Step One Write the symbols for the ions in the compound. Na + CO 3 -2

12. Determine the correct ratio of sodium ions to carbonate ions. Na + CO 3 -2 +1 (2) + -2(1) = 0 Na 2 CO 3

13. Al +3 SO 4 -2 +3(2) + -2(3) = 0 Al 2 (SO 4 ) 3