Naming Ionic Compounds - Nomenclature Rules - Free Printable

Let’s go step by step to fill in the missing names and formulas for each ionic compound.

We’ll use these rules:
- For names from formulas: Identify the metal (cation) and nonmetal/polyatomic ion (anion). If the metal can have more than one charge (like iron, copper, tin), we need a Roman numeral. If it only has one common charge (like sodium, magnesium, aluminum), no Roman numeral is needed.
- For formulas from names: Write the symbols of the ions, then balance the charges so the total positive = total negative.

---

Left Column: Given Formula → Find Name

1. ZnCl₂
Zinc always forms Zn²⁺. Chloride is Cl⁻. So two chlorides balance one zinc.
→ zinc chloride

2. TiI₄
Iodide is I⁻. Four iodides mean total -4 charge. So titanium must be +4. Titanium can have multiple charges → use Roman numeral.
→ titanium(IV) iodide

3. Ag₂SO₃
Silver is usually Ag⁺ (only one common charge). SO₃²⁻ is sulfite. Two silvers (+2) balance sulfite (-2).
→ silver sulfite

4. CaSO₄
Calcium is Ca²⁺. SO₄²⁻ is sulfate. Charges balance.
→ calcium sulfate

5. Mg₃P₂
Magnesium is Mg²⁺. Phosphorus as anion is phosphide P³⁻. Three Mg²⁺ = +6, two P³⁻ = -6.
→ magnesium phosphide

6. K₂CO₃
Potassium is K⁺. CO₃²⁻ is carbonate. Two potassiums balance carbonate.
→ potassium carbonate

7. AlPO₄
Aluminum is Al³⁺. PO₄³⁻ is phosphate. Charges balance.
→ aluminum phosphate

8. NH₄OH
NH₄⁺ is ammonium. OH⁻ is hydroxide.
→ ammonium hydroxide

9. Co₃N₂
Nitrogen as anion is nitride N³⁻. Two nitrides = -6. Three cobalts must = +6 → each Co is +2. Cobalt has variable charge → use Roman numeral.
→ cobalt(II) nitride

10. MgBr₂
Magnesium is Mg²⁺. Bromide is Br⁻. Two bromides balance one magnesium.
→ magnesium bromide

---

Right Column: Given Name → Find Formula

11. sodium hydroxide
Sodium = Na⁺, Hydroxide = OH⁻ → combine 1:1
→ NaOH

12. copper(I) arsenide
Copper(I) = Cu⁺, Arsenide = As³⁻ → need 3 Cu⁺ to balance 1 As³⁻
→ Cu₃As

13. beryllium chloride
Beryllium = Be²⁺, Chloride = Cl⁻ → need 2 Cl⁻ to balance
→ BeCl₂

14. calcium oxide
Calcium = Ca²⁺, Oxide = O²⁻ → 1:1 ratio
→ CaO

15. ammonium sulfite
Ammonium = NH₄⁺, Sulfite = SO₃²⁻ → need 2 NH₄⁺ to balance
→ (NH₄)₂SO₃

16. iron(III) oxide
Iron(III) = Fe³⁺, Oxide = O²⁻ → LCM of 3 and 2 is 6 → 2 Fe³⁺ and 3 O²⁻
→ Fe₂O₃

17. vanadium(V) phosphate
Vanadium(V) = V⁵⁺, Phosphate = PO₄³⁻ → LCM of 5 and 3 is 15 → 3 V⁵⁺ and 5 PO₄³⁻
→ V₃(PO₄)₅

18. magnesium nitrate
Magnesium = Mg²⁺, Nitrate = NO₃⁻ → need 2 nitrates
→ Mg(NO₃)₂

19. silver cyanide
Silver = Ag⁺, Cyanide = CN⁻ → 1:1
→ AgCN

20. calcium phosphate
Calcium = Ca²⁺, Phosphate = PO₄³⁻ → LCM of 2 and 3 is 6 → 3 Ca²⁺ and 2 PO₄³⁻
→ Ca₃(PO)₂

---

Final Answer:

| # | Name | # | Formula |
|---|-----------------------|---|---------------------|
| 1 | zinc chloride | 11| NaOH |
| 2 | titanium(IV) iodide | 12| Cu₃As |
| 3 | silver sulfite | 13| BeCl₂ |
| 4 | calcium sulfate | 14| CaO |
| 5 | magnesium phosphide | 15| (NH₄)₂SO₃ |
| 6 | potassium carbonate | 16| Fe₂O₃ |
| 7 | aluminum phosphate | 17| V₃(PO)₅ |
| 8 | ammonium hydroxide | 18| Mg(NO₃)₂ |
| 9 | cobalt(II) nitride | 19| AgCN |
|10 | magnesium bromide | 20| Ca₃(PO₄)₂ |