1. O3: O = 0
2. Al: Al = 0
3. HF: H = +1, F = -1
4. Cl2: Cl = 0
5. NaCl: Na = +1, Cl = -1
6. MgO: Mg = +2, O = -2
7. O2: O = 0
8. Na2S: Na = +1, S = -2
9. Cl2O7: Cl = +7, O = -2
10. H2SO4: H = +1, S = +6, O = -2
11. K2Cr2O7: K = +1, Cr = +6, O = -2
12. HNO3: H = +1, N = +5, O = -2
13. Cu(NO3)2: Cu = +2, N = +5, O = -2
14. Ba(OH)2: Ba = +2, O = -2, H = +1