High School Chemistry  ·  Practice by Skill

Naming Compounds Practice Problems

Chemical nomenclature is the system for turning a formula into a name and a name back into a formula. The trick is picking the right set of rules for the type of compound in front of you. Practice below covers ionic names, Roman numerals, covalent prefixes, polyatomic ions, and writing formulas.

What you’ll practice

  • Choosing the rule set: decide whether a compound is ionic, covalent, or an acid before you name it.
  • Ionic names and Roman numerals: name metal and nonmetal pairs, including metals with more than one charge.
  • Polyatomic ions: recognize and keep common polyatomic ions together as a unit.
  • Writing formulas from names: balance the charges so the formula has no net charge.

Learn the method first →

A quick example: writing a formula from a name

Write the formula for calcium phosphate.

Calcium forms Ca2+ and phosphate is PO43−. Find the smallest numbers that make the charges cancel: 3 × (+2) = +6 and 2 × (−3) = −6.

Put parentheses around the polyatomic ion so its subscript applies to the whole group.

The formula is Ca3(PO4)2.

3 free naming compounds problems

Give each one a real try before you open the solution. Your answer is checked as soon as you submit it, and the worked solution shows every step so you can see exactly where a setup went wrong.

#1Metal Charge
In the compound MnO2, oxygen has a -2 charge. What is the charge on the manganese (Mn) ion?
#2Ionic Nomenclature
What is the correct IUPAC name for the compound NaCl?
#3Formula Writing
What is the correct chemical formula for iron(III) sulfate? (Fe3+ and SO42-)

Questions you might have about naming compounds

How do I name an ionic compound?
Name the metal (cation) first, then the nonmetal (anion) with its ending changed to -ide, so NaCl is sodium chloride. If the anion is a polyatomic ion, use its name unchanged, as in sodium nitrate.
When do I use Roman numerals in a name?
Use them when the metal can form more than one charge, which includes most transition metals. The numeral gives the charge of the metal ion, so iron(III) means Fe3+.
How do I name a covalent compound?
Use prefixes (mono-, di-, tri-, tetra-, and so on) to show how many atoms of each element there are, and end the second element in -ide. CCl4 is carbon tetrachloride. Skip mono- on the first element.
How do I write a formula from a compound name?
Write the ions with their charges, then choose subscripts so the total positive and negative charge adds to zero. Use parentheses when you need more than one polyatomic ion.
High School Chemistry · Naming Compounds Practice Problems