This free naming ionic compounds worksheet gives Grade 11 students 37 questions on writing names and formulas for ionic compounds, from simple salts like NaCl to compounds with Roman numerals and polyatomic ions.
It covers binary compounds, multivalent metals, polyatomic ions, common naming errors and a short challenge section. An ion reference table and a complete answer key are included.
- Grade 11 · SCH3U
- 37 marks
- 35–45 minutes
- Answer key included
What's in This Naming Ionic Compounds Worksheet
The sheet builds one rule at a time, so students master binary names before adding Roman numerals and polyatomic ions.
| Part | Skill practised | Marks |
|---|
| A | Binary compounds: formula → name | 6 |
| B | Binary compounds: name → formula | 6 |
| C | Multivalent metals and Roman numerals | 8 |
| D | Polyatomic ions, both directions | 10 |
| E | Spot the mistake | 4 |
| F | Challenge: finding the metal's charge, and ammonium phosphate | 3 |
It matches the Ontario SCH3U expectations for chemical nomenclature in the Matter, Chemical Trends and Chemical Bonding unit. Names follow IUPAC (Stock system) conventions, so iron(III) rather than "ferric."
How to Name Ionic Compounds
Every name on this naming ionic compounds worksheet follows three rules:
- Metal first, unchanged. Na becomes sodium; Ca becomes calcium.
- Non-metal second, ending in -ide. Chlorine becomes chloride and oxygen becomes oxide. Polyatomic ions keep their own names, such as sulfate or nitrate.
- Roman numerals for multivalent metals. If the metal can form more than one charge, show its charge in brackets: FeCl3 is iron(III) chloride.
Students need to know the common ions. These are the ones used on the worksheet, and the PDF prints them on page 1:
Common cationsNa+, K+, Li+, Ag+, NH4+ (ammonium)
Mg2+, Ca2+, Zn2+, Al3+
Multivalent metalsFe2+ / Fe3+
Cu+ / Cu2+
Pb2+ / Pb4+
Sn2+ / Sn4+
Monatomic anions (-ide)F− fluoride, Cl− chloride
Br− bromide, I− iodide
O2− oxide, S2− sulfide
N3− nitride, P3− phosphide
Polyatomic anionsOH− hydroxide, NO3− nitrate
NO2− nitrite, HCO3− hydrogen carbonate
SO42− sulfate, SO32− sulfite
CO32− carbonate, PO43− phosphate
Going from name to formula is where most marks are lost. Use the charges so they add to zero. For aluminum sulfide:
- Write the ions with charges: Al3+ and S2−.
- Find the lowest common multiple of 3 and 2, which is 6.
- You need two Al3+ (+6) and three S2− (−6), giving Al2S3.
Many teachers call this the criss-cross method: each ion's charge becomes the other's subscript, then reduce if possible. For polyatomic ions, keep the ion in brackets when you need more than one: Ca(NO3)2. If you want students to classify bonds first, our ionic or covalent worksheet is the step before this one. For the official rules, the IUPAC nomenclature page covers naming conventions, and the Wikipedia list of polyatomic ions is a handy extended reference.
Naming Ionic Compounds Practice Questions
These are the same questions as in the naming ionic compounds worksheet PDF. Try them, then open the answers below.
Part A – Binary Compounds: Formula → Name
- NaCl
- MgBr2
- Al2O3
- K2S
- CaF2
- Li3N
Part B – Binary Compounds: Name → Formula
- calcium chloride
- sodium oxide
- aluminum sulfide
- magnesium nitride
- potassium iodide
- zinc oxide
Part C – Multivalent Metals (Roman Numerals)
Formula → name
- FeCl3
- CuO
- Cu2O
- PbO2
- SnCl2
Name → formula
- iron(II) sulfide
- copper(II) nitride
- lead(II) bromide
Part D – Polyatomic Ions
Formula → name
- NaOH
- CaCO3
- (NH4)2SO4
- KNO3
- Mg3(PO4)2
Name → formula
- aluminum hydroxide
- ammonium chloride
- sodium hydrogen carbonate
- calcium nitrate
- iron(III) sulfate
Part E – Spot the Mistake
Explain the error and write the correct answer.
- A student writes the formula for magnesium chloride as MgCl.
- A student names FeCl2 as “iron chloride.”
- A student writes calcium hydroxide as CaOH2.
- A student names NaCl as “sodium chlorine.”
Part F – Challenge
- What is the charge on iron in Fe2O3? Show your work, then name the compound.
- Why does calcium chloride not need a Roman numeral, but copper chloride does?
- Write the formula and name for the compound formed by ammonium and phosphate ions.
Naming Ionic Compounds Worksheet Answer Key
Open each part to check your work. The printable answer key is on pages 3–4 of the PDF.
Part A answers (Q1–6)
- NaCl → sodium chloride
- MgBr2 → magnesium bromide
- Al2O3 → aluminum oxide
- K2S → potassium sulfide
- CaF2 → calcium fluoride
- Li3N → lithium nitride
Part B answers (Q7–12)
- calcium chloride → CaCl2
- sodium oxide → Na2O
- aluminum sulfide → Al2S3
- magnesium nitride → Mg3N2
- potassium iodide → KI
- zinc oxide → ZnO
Part C answers (Q13–20)
- FeCl3 → iron(III) chloride
- CuO → copper(II) oxide
- Cu2O → copper(I) oxide
- PbO2 → lead(IV) oxide
- SnCl2 → tin(II) chloride
- iron(II) sulfide → FeS
- copper(II) nitride → Cu3N2
- lead(II) bromide → PbBr2
Part D answers (Q21–30)
- NaOH → sodium hydroxide
- CaCO3 → calcium carbonate
- (NH4)2SO4 → ammonium sulfate
- KNO3 → potassium nitrate
- Mg3(PO4)2 → magnesium phosphate
- aluminum hydroxide → Al(OH)3
- ammonium chloride → NH4Cl
- sodium hydrogen carbonate → NaHCO3
- calcium nitrate → Ca(NO3)2
- iron(III) sulfate → Fe2(SO4)3
Part E answers (Q31–34)
- Charges don’t balance: Mg2+ needs two Cl−. Correct: MgCl2
- Iron is multivalent, so the charge must be shown. Correct: iron(II) chloride
- A polyatomic ion used more than once needs brackets. Correct: Ca(OH)2
- A monatomic anion ends in “-ide.” Correct: sodium chloride
Part F answers (Q35–37)
- 3 O × (−2) = −6, so 2 Fe = +6 and each Fe is 3+. Name: iron(III) oxide
- Calcium only forms Ca2+; copper can be Cu+ or Cu2+, so its charge must be stated.
- (NH4)3PO4, ammonium phosphate
5 Common Naming Mistakes
Part E of the naming ionic compounds worksheet is built around these, because they cost students marks on every test.
- Unbalanced charges. MgCl looks fine until you check: Mg2+ needs two Cl−, so it's MgCl2.
- Missing Roman numerals. "Iron chloride" could be FeCl2 or FeCl3. The numeral is required for multivalent metals.
- Roman numeral = subscript. The numeral is the metal's charge, not how many atoms there are. Fe2O3 is iron(III), not iron(II).
- Forgetting brackets. CaOH2 means something different from Ca(OH)2.
- Wrong ending. Monatomic anions end in -ide (chloride, not chlorine). Polyatomic ions keep their own endings (sulfate, nitrite).
How to Use This Naming Ionic Compounds Worksheet in Class
As a teacher, I split it across the nomenclature lessons:
- Day 1: Parts A and B after introducing binary ionic compounds.
- Day 2: Part C once Roman numerals are taught, and Part D after polyatomic ions.
- Review: Parts E and F as an exit ticket or quiz warm-up. The spot-the-mistake questions quickly show who is guessing.
For more practice, follow up with the chemical bonding quiz or try the free chemistry calculators to find molar masses of the compounds students just named.
Frequently Asked Questions
Is this naming ionic compounds worksheet free?
Yes. The worksheet and answer key are free to download and print as a PDF, with no account needed.
How do you name an ionic compound?
Name the metal (cation) first, then the non-metal (anion) with its ending changed to -ide. Add a Roman numeral for multivalent metals such as iron or copper, and keep the name of polyatomic ions unchanged.
When do you use Roman numerals in ionic compound names?
Only for metals that can form more than one charge, such as Fe, Cu, Pb and Sn. The numeral shows the charge, so FeCl3 is iron(III) chloride.
Why do some formulas need brackets?
Brackets go around a polyatomic ion when more than one of that ion is needed, such as Ca(OH)2 or Mg3(PO4)2.
What grade is this naming ionic compounds worksheet for?
It is written for Grade 11 chemistry (Ontario SCH3U) and suits any introductory high school chemistry course.
More Free Grade 11 Chemistry Resources
Ready to practise? Download the free naming ionic compounds worksheet PDF (use the Download button above), print it double-sided, and keep the answer key pages for marking.