Polyatomic Ions Quiz

Polyatomic ions are charged groups of atoms that behave as single units in chemical reactions. Unlike monatomic ions such as Na⁺ or Cl⁻, polyatomic ions consist of two or more atoms bonded together with an overall electric charge. Mastering them is essential for writing chemical formulas and balancing equations in general chemistry courses.

Common Polyatomic Ions You Must Know

Among the most frequently tested are the nitrate ion (NO₃⁻), nitrite (NO₂⁻), sulfate (SO₄²⁻), sulfite (SO₃²⁻), phosphate (PO₄³⁻), carbonate (CO₃²⁻), and ammonium (NH₄⁺). The "-ate" suffix generally indicates one more oxygen atom than the "-ite" form of the same ion. General chemistry students are typically expected to memorize at least twenty polyatomic ions for exams.

Beyond naming, you need to know their charges to correctly write ionic compound formulas. For example, calcium phosphate is Ca₃(PO₄)₂ because you need three calcium ions (+2 each) to balance two phosphate ions (−3 each). Review your chemistry fundamentals and tackle this polyatomic ion challenge!