Polyatomic Ions Section 3 6 Polyatomic Ions Sometimes

Polyatomic Ions Section 3. 6

Polyatomic Ions • Sometimes a group of atoms come together in a structure such that they act like one single ion with a single charge • Polyatomico Poly means many o Atomic means atoms • A polyatomic ion has 2 or more nonmetals grouped together that have one ionic charge 2

Polyatomic Ions • Can tell they are ions because they are paired with a metal • Ex. Mg. SO 4 o Mg is the metal, with a charge of 2+ o SO 4 is the nonmetal polyatomic ion, with a charge of 2 - • Be familiar with the polyatomic ions on the next slide o Know formula, name, and charge 3

Common Polyatomic Ions Nonmetal Carbon Formula Name CO 32 - carbonate HCO 3 - hydrogen carbonate or bicarbonate CH 3 CO 2 - acetate CN- cyanide NO 3 - nitrate NO 2 - nitrite Oxygen OH- hydroxide Phosphorus PO 43 - phosphate HPO 42 - hydrogen phosphate H 2 PO 4 - dihydrogen phosphate SO 42 - sulfate HSO 4 - hydrogen sulfate or bisulfate SO 32 - sulfite HSO 3 - hydrogen sulfite or bisulfite Nitrogen Sulfur 4

Formula and Naming Rules • Do not change • Still balance using the single charge • Name with the polyatomic name, no need to change any endings The charges are not equal in magnitude, +2 and -1 Two OH- anions are needed to balance charge Use a subscript outside the parentheses Use parentheses around all atoms of the ion 5

Example #1 Name or write the formula for the following compounds: 1. Mg. SO 4 2. Calcium carbonate 3. Silver nitrate 4. Na 3 PO 4 5. Al(OH)3 6

Example #1 Solved 1. 2. 3. 4. 5. Magnesium sulfate Ca. CO 3 Ag. NO 3 Sodium phosphate Aluminum hydroxide 7