Polyatomic ions quiz: match formulas, names and charges
Practice the common polyatomic ions, from ammonium (NH₄⁺) to phosphate (PO₄³⁻). You need their names, formulas and charges to write and name ionic compounds such as Ca(NO₃)₂ and (NH₄)₂SO₄, so learning them early saves time in every later topic.
Best: —
How it works
Each round has 10 questions drawn from the site’s list of polyatomic ions. Some questions show a formula and ask for the ion’s name, and others show a name and ask for its charge; you pick from four options. Every answer gets instant feedback, and your best score is saved in your browser.
Play it three ways: a classic round of 10 questions, a 60-second speed round (25 right answers earns a star), or survival, where you keep going until you miss three.
Tips
- Use the sentence “Nick the Camel ate a Clam for Supper in Phoenix”: the consonants give the number of oxygen atoms and the vowels give the negative charge, so Nick is NO₃⁻, Camel is CO₃²⁻, Clam is ClO₃⁻, Supper is SO₄²⁻ and Phoenix is PO₄³⁻.
- An -ite ion has one fewer oxygen atom than its -ate partner but the same charge: sulfate is SO₄²⁻ and sulfite is SO₃²⁻.
- Per- adds one oxygen to an -ate ion and hypo- removes one from an -ite ion: perchlorate is ClO₄⁻ and hypochlorite is ClO⁻.
- Adding hydrogen makes the charge one less negative: phosphate PO₄³⁻, hydrogen phosphate HPO₄²⁻, dihydrogen phosphate H₂PO₄⁻.