Naming ionic compounds worksheet
This naming ionic compounds worksheet provides (1) a compact rule set, (2) guided examples, (3) practice problems, and (4) a complete answer key. The focus is introductory general chemistry nomenclature: binary ionic compounds, variable-charge metals (Roman numerals), and common polyatomic ions.
Core idea: An ionic compound is electrically neutral, so the total positive charge from the cation(s) equals the total negative charge from the anion(s).
Naming pattern: cation name + (Roman numeral if needed) + anion name (-ide for monatomic anions, or the polyatomic ion name).
Rules to use on the worksheet
- Identify the ions. Metals form cations; nonmetals form anions. Polyatomic ions behave as a single charged unit.
- Name the cation first. Use the element name (e.g., sodium, calcium). If the metal can have more than one charge (common for transition metals), include a Roman numeral showing the cation charge (e.g., iron(III)).
- Name the anion second. A monatomic anion ends in -ide (chloride, oxide, sulfide). A polyatomic anion keeps its standard name (nitrate, sulfate, hydroxide).
- Writing the formula: choose subscripts so the total charge is zero (reduce to lowest whole-number ratio). Parentheses are used only when a polyatomic ion appears more than once.
Common ions reference (mini table)
| Ion type | Formula | Name | Charge |
|---|---|---|---|
| Cation | Na+ | sodium | +1 |
| Cation | Ca2+ | calcium | +2 |
| Cation | Al3+ | aluminum | +3 |
| Cation (polyatomic) | NH4+ | ammonium | +1 |
| Anion | Cl− | chloride | −1 |
| Anion | O2− | oxide | −2 |
| Anion (polyatomic) | NO3− | nitrate | −1 |
| Anion (polyatomic) | SO42− | sulfate | −2 |
| Anion (polyatomic) | OH− | hydroxide | −1 |
Visualization: quick decision flow for ionic naming and formulas
Guided examples (use these as models)
Example 1 (binary, fixed-charge metal): Name CaCl2.
- Ca is a Group 2 metal → Ca2+ (calcium).
- Cl is a halogen → Cl− (chloride).
- Name = calcium chloride.
Charge check (optional): \( \text{Ca}^{2+} + 2\text{Cl}^{-} \rightarrow \text{CaCl}_2 \)
Example 2 (variable-charge metal): Name FeCl3.
- Three Cl− contribute total −3, so Fe must be +3.
- Name = iron(III) chloride.
Charge logic: \( 3 \times (-1) = -3 \Rightarrow \text{Fe} = +3 \)
Example 3 (polyatomic ion): Write the formula for calcium nitrate.
- Calcium is Ca2+.
- Nitrate is NO3−.
- Two nitrates are needed to balance +2 → Ca(NO3)2.
Worksheet A: Name these ionic compounds (formula → name)
Write the correct name on the blank line. Include Roman numerals where required.
| # | Formula | Compound name |
|---|---|---|
| 1 | NaCl | |
| 2 | MgO | |
| 3 | Al2S3 | |
| 4 | NH4Br | |
| 5 | FeO | |
| 6 | FeCl3 | |
| 7 | Cu2O | |
| 8 | SnI4 | |
| 9 | Ca(OH)2 | |
| 10 | KNO3 | |
| 11 | Al2(SO4)3 | |
| 12 | Pb(NO3)2 |
Worksheet B: Write formulas (name → formula)
Write the correct formula. Use parentheses for polyatomic ions only when the polyatomic ion repeats.
| # | Compound name | Formula |
|---|---|---|
| 13 | calcium fluoride | |
| 14 | aluminum oxide | |
| 15 | iron(II) sulfide | |
| 16 | iron(III) sulfate | |
| 17 | copper(I) chloride | |
| 18 | ammonium carbonate | |
| 19 | magnesium hydroxide | |
| 20 | lead(IV) oxide | |
| 21 | potassium phosphate | |
| 22 | calcium nitrate |
Answer key
| # | Correct answer |
|---|---|
| 1 | sodium chloride |
| 2 | magnesium oxide |
| 3 | aluminum sulfide |
| 4 | ammonium bromide |
| 5 | iron(II) oxide |
| 6 | iron(III) chloride |
| 7 | copper(I) oxide |
| 8 | tin(IV) iodide |
| 9 | calcium hydroxide |
| 10 | potassium nitrate |
| 11 | aluminum sulfate |
| 12 | lead(II) nitrate |
| 13 | CaF2 |
| 14 | Al2O3 |
| 15 | FeS |
| 16 | Fe2(SO4)3 |
| 17 | CuCl |
| 18 | (NH4)2CO3 |
| 19 | Mg(OH)2 |
| 20 | PbO2 |
| 21 | K3PO4 |
| 22 | Ca(NO3)2 |
Self-check: common mistakes to avoid
- No prefixes (mono-, di-, tri-) in ionic compound names.
- Use Roman numerals only when the metal can have multiple charges (Fe, Cu, Sn, Pb, etc.).
- Do not change polyatomic ion spelling (nitrate stays nitrate; sulfate stays sulfate).
- Parentheses only when needed: Ca(NO3)2 needs parentheses, but KNO3 does not.
- Reduce subscripts to the simplest whole-number ratio after balancing charges.
Direct takeaway
A naming ionic compounds worksheet becomes straightforward when every problem is treated as a charge-balance task: identify ions, determine the cation charge (Roman numeral if needed), apply the correct anion name, and ensure the formula sums to zero net charge.