Here’s a version of common oxidation states:
1. Hydrogen (H)
- +1 with nonmetals (HCl, H₂O)
- –1 in metal hydrides (NaH, CaH₂)
2. Oxygen (O)
- –2 usually (H₂O, CO₂)
- –1 in peroxides (H₂O₂)
- +2 in OF₂
3. Alkali Metals (Li, Na, K, …)
- Always +1 (NaCl, K₂O)
4. Alkaline Earth Metals (Be, Mg, Ca, …)
- Always +2 (MgO, CaCl₂)
5. Transition Metals
- Can have multiple states:
- Fe → +2, +3
- Cu → +1, +2
- Cr → +2, +3, +6
6. Halogens (F, Cl, Br, I)
- Usually –1 (NaCl, HBr)
- Can be positive with oxygen: Cl → +1, +3, +5, +7
7. Other Nonmetals
- N → –3 (NH₃), +3 (NO₂⁻), +5 (NO₃⁻)
- S → –2 (H₂S), +4 (SO₂), +6 (SO₄²⁻)
- P → –3 (PH₃), +3 (H₃PO₃), +5 (H₃PO₄)
In short:
- Metals → usually positive
- Nonmetals → usually negative, but can be positive in oxides or oxyanions