Polyatomic Ions

It is also possible for several nonmetal atoms to cluster together in groups and form ions. They are called polyatomic ions. The formulas and charges of these polyatomic ions are not nearly so predictable as the simple anions you just studied. Nor are they all anions. The eight that you will need to memorize are listed here (and in example 8 in your workbook).

You need to know the names and formulas (including charges) for these eight polyatomic ions. You do not need to memorize the names for this lesson, but you will need to memorize them for lesson 9. You do need to memorize the formulas and charges for each of these polyatomic ions for this lesson.

Important Polyatomic Ions
Name	Formula
acetate	C₂H₃O₂^-
carbonate	CO₃^2-
nitrate	NO₃^-
phosphate	PO₄^3-
sulfate	SO₄^2-
chlorate	ClO₃^-
hydroxide	OH^-
ammonium	NH₄⁺

Note that nearly all have "-ate" endings. Note that nearly all contain oxygen with one other element, and nearly all have negative charges.

Soon (by the end of this lesson) you should memorize these, but in the meantime use this list when you need to work with the names and formulas of these polyatomic ions.

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E-mail instructor: Eden Francis

Clackamas Community College
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