General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C. Timberlake © 2016 Pearson Education, Inc. 6.4 Polyatomic Ions Sodium chlorite, NaClO 2, is used in the processing and bleaching of pulp from wood fibers and recycled cardboard. Learning Goal Write the name and formula for an ionic compound containing a polyatomic ion.

General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C. Timberlake © 2016 Pearson Education, Inc. Polyatomic Ions Polyatomic ions are a group of atoms with an overall charge. often consist of a nonmetal such as phosphorus, sulfur, carbon, or nitrogen and oxygen. usually have a 1−, 2−, or 3− charge. have a negative charge, except for NH 4 +, ammonium, which has a positive charge,

General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C. Timberlake © 2016 Pearson Education, Inc. Polyatomic Ions Many products contain polyatomic ions, which are groups of ions that have an ionic charge.

General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C. Timberlake © 2016 Pearson Education, Inc. Polyatomic Ions, Names, and Formulas

General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C. Timberlake © 2016 Pearson Education, Inc. Names of Polyatomic Ions 1.Names of most common polyatomic ions end in ate. SO 4 2− sulfate PO 4 3− phosphate NO 3 − nitrate 2.When a related ion has one less oxygen, its name ends in ite. SO 3 2− sulfite PO 3 3− phosphite NO 2 − nitrite

General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C. Timberlake © 2016 Pearson Education, Inc. Names of Polyatomic Ions 3.Exceptions to these rules are the following: CN − cyanide OH − hydroxide 4.Add an H + to the polyatomic ion, and add +1 to its charge. CO 3 2− + H + =HCO 3 − carbonate+ H + =bicarbonate or hydrogen carbonate SO 4 2− + H + =HSO 4 − sulfate+ H + =bisulfate or hydrogen sulfate

General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C. Timberlake © 2016 Pearson Education, Inc. Names of Polyatomic Ions 5.Halogens form 4 polyatomic ions with oxygen. Each has a −1 charge. ClO 4 − perchlorate ClO 3 − chlorate ClO 2 − chlorite ClO − hypochlorite Sodium chlorite is used in the processing and bleaching of pulp from wood fibers and recycled cardboard.

General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C. Timberlake © 2016 Pearson Education, Inc. Writing Formulas for Compounds Containing Polyatomic Ions When writing formulas for ionic compounds containing polyatomic ions, we use the same rules of charge balance as those for simple ionic compounds. Consider the formula for magnesium nitrate: Magnesium ion Nitrate ion Mg 2+ + NO 3 − NO 3 − (2+) + 2(1−)=0 Mg NO 3 − =Mg(NO 3 ) 2 Parentheses are placed around the polyatomic ion, and the subscript is placed just outside the parentheses.

General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C. Timberlake © 2016 Pearson Education, Inc. Guide to Writing Formulas with Polyatomic Ions

General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C. Timberlake © 2016 Pearson Education, Inc. Writing Formulas with Polyatomic Ions, Aluminum Bicarbonate Write the formula for aluminum bicarbonate. STEP 1 Identify the cation and polyatomic ion (anion). CationPolyatomic ion Al 3+ HCO 3 − STEP 2 Balance the charges. Al 3+ HCO 3 − HCO 3 − 1(3+) +3(1−) = 0

General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C. Timberlake © 2016 Pearson Education, Inc. Writing Formulas with Polyatomic Ions, Aluminum Bicarbonate Write the formula for aluminum bicarbonate. STEP 3 Write the formula, cation first, using the subscripts from charge balance. Al(HCO 3 ) 3

General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C. Timberlake © 2016 Pearson Education, Inc. Study Check Write the formula for sodium phosphate.

General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C. Timberlake © 2016 Pearson Education, Inc. Solution Write the formula for sodium phosphate. STEP 1Identify the cation and polyatomic ion (anion). CationPolyatomic ion Na + PO 4 3− STEP 2Balance the charges. Na + PO 4 3− Na + 3(1+) + 1(3−) = 0

General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C. Timberlake © 2016 Pearson Education, Inc. Solution Write the formula for sodium phosphate. STEP 3 Write the formula, cation first, using the subscripts from charge balance. Na 3 PO 4

General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C. Timberlake © 2016 Pearson Education, Inc. Naming Compounds with Polyatomic Ions When naming ionic compounds containing polyatomic ions, first write the positive ion, usually a metal. write the name of the polyatomic ion second. Recognizing polyatomic ions in a chemical formula helps to name it correctly. As with other ionic compounds, no prefixes are used.

General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C. Timberlake © 2016 Pearson Education, Inc. Compounds with Polyatomic Ions

General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C. Timberlake © 2016 Pearson Education, Inc. Study Check Select the correct formula for each. 1.aluminum nitrate A. AlNO 3 B.Al(NO) 3 C.Al(NO 3 ) 3 2.copper(II) nitrate A. CuNO 3 B.Cu(NO 3 ) 2 C.Cu 2 (NO 3 ) 3.iron(III) hydroxide A. FeOHB.Fe 3 OHC.Fe(OH) 3 4.tin(IV) hydroxide A. Sn(OH) 4 B.Sn(OH) 2 C.Sn 4 (OH)

General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C. Timberlake © 2016 Pearson Education, Inc. Solution Select the correct formula for each. 1.aluminum nitrateC.Al(NO 3 ) 3 2.copper(II) nitrateB.Cu(NO 3 ) 2 3.iron(III) hydroxideC.Fe(OH) 3 4.tin(IV) hydroxideA.Sn(OH) 4

General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C. Timberlake © 2016 Pearson Education, Inc. Guide to Naming Compounds with Polyatomic Ions

General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C. Timberlake © 2016 Pearson Education, Inc. Flow Chart, Naming Ionic Compounds

General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C. Timberlake © 2016 Pearson Education, Inc. Study Check Name the following ionic compounds: A.Ca(NO 3 ) 2 B.FePO 4

General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C. Timberlake © 2016 Pearson Education, Inc. Solution Name the following ionic compounds: STEP 1 STEP 2STEP 3STEP 4 IdentifyNameNameName cation/anioncationanion compound A. Ca(NO 3 ) 2 Ca 2+ NO 3 − calciumnitratecalcium nitrate B. FePO 4 Fe 3+ PO 4 3− iron(III)phosphateiron(III) phosphate

General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C. Timberlake © 2016 Pearson Education, Inc. Study Check Name each of the following compounds containing polyatomic ions. A.MgSO 3 B.MgSO 4 C.Pb 3 (PO 3 ) 2

General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C. Timberlake © 2016 Pearson Education, Inc. Solution Name the following ionic compounds: STEP 1STEP 2STEP 3STEP 4 IdentifyNameNameName cation/anioncationanioncompound A. MgSO 3 Mg 2+ SO 3 2− magnesiumsulfitemagnesium sulfite B. MgSO 4 Mg 2+ SO 4 2− magnesiumsulfatemagnesium sulfate C. Pb 3 (PO 3 ) 2 Pb 2+ PO 3 3− lead(II)phosphitelead(II) phosphite

General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C. Timberlake © 2016 Pearson Education, Inc. Study Check Name each of the following compounds: A.Fe 2 (SO 4 ) 3 B.Ba 3 (PO 3 ) 2 C.NiCO 3

General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C. Timberlake © 2016 Pearson Education, Inc. Solution Name the following ionic compounds: STEP 1STEP 2STEP 3STEP 4 IdentifyNameNameName cation/anioncationanion compound A. Fe 2 (SO 4 ) 3 Fe 3+ SO 4 2− iron(III)sulfateiron(III) sulfate B. Ba 3 (PO 3 ) 2 Ba 2+ PO 3 3− bariumphosphitebarium phosphite C. NiCO 3 Ni 2+ CO 3 2− nickel(II)carbonatenickel(II) carbonate