Polyatomic Ions table E

Definition polyatomic ion: group of 2 + atoms that acts as one ion and has one charge SO 4 -2

Ammonium NH 4 +1

Acetate CH 3 COO -1 or C 2 H 3 O 2 -1

Carbonate CO 3 -2

Cyanide CN -1

Chlorate ClO 3 -1

Nitrate NO 3 -1

Hydroxide OH -1

Phosphate PO 4 -3

Sulfate SO 4 -2

Hydromium H 3 O +1

Ionic formulas with Polyatomic Ions What’s the formula for the compound formed from CO 3 -2 and Mg +2 ? charges must add up to zero write the symbols, positive first! MgCO 3

Try a few more: Na +1 and OH -1 K +1 and HCO 3 -1 Mg +2 and CO 3 -2 Li +1 and NO Ca +2 and SO 4 -2NaOH KHCO 3 MgCO 3 LiNO 3 CaSO 4

These are more challenging: Mg +2 and (PO 4 ) -3 Al +3 and (NO 3 ) -1 Fe +2 and OH -1 Hg 2 +2 and SCN -1 Mg +2 and HCO 3 -1 Al +3 and C 2 O 4 -2 Mg 3 (PO 4 ) 2 Al(NO 3 ) 3 Fe(OH) 2 Hg 2 (SCN) 2 Mg(HCO 3 ) 2 Al 2 (C 2 O 4 ) 3

Naming compounds with polyatomics 1.positive ion always written first 2.(+) ion is metal - check if more than one oxidation state - if > 1 need roman numeral in name (–) ion is polyatomic - 2 nd part name is name of polyatomic (don’t modify ending)

Name the following NaOHNaOH KHCO 3KHCO 3 LiNO 3LiNO 3 CaSO 4CaSO 4 Al(NO 3 ) 3Al(NO 3 ) 3  Fe(OH) 2  CuSO 4  CuSCN Sodium hydroxide Potassium hydrogen carbonate Lithium nitrate Calcium sulfate Aluminum nitrate Iron (II) hydroxide Copper (II) sulfate Copper (I) thiocyanate

Summary for Ionic Compounds with Polyatomic ions Formula: positive first, always metal > 1 oxidation state, name needs roman numeral Name = name metal + name polyatomic