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Polyatomic Ions. Memorize the top ten (see table E). Definition. polyatomic ion : group of two or more atoms that acts as one ion and has one charge SO 4 -2 Ternary Compounds contain 3 or more elements. Ammonium
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Polyatomic Ions Memorize the top ten (see table E)
Definition polyatomic ion: group of two or more atoms that acts as one ion and has one charge SO4-2 Ternary Compounds contain 3 or more elements
Ammonium NH4+1
Acetate CH3COO -1 or C2H3O2-1
Carbonate CO3-2
Cyanide CN -1
Chlorate ClO3-1
Nitrate NO3-1
Hydroxide OH -1
Phosphate PO4-3
Sulfate SO4-2
Hydromium H3O +1
Ionic formulas with Polyatomic Ions • What’s the formula for the compound formed from CO3-2 and Mg+2? • The charges must add up to zero, so just write the symbols, positive first! MgCO3
Try a few more: • Na+1 and OH-1 • K +1 and HCO3-1 • Mg+2 and CO3-2 • Li +1 and NO3-1 • -Ca+2 and SO4-2 NaOH KHCO3 MgCO3 LiNO3 CaSO4
These are more challenging: • Mg+2 and (PO4)-3 • Al+3 and (NO3)-1 • Fe+2 and OH-1 • Hg2+2 and SCN-1 • Mg+2 and HCO3-1 • Al+3 and C2O4-2 Mg3(PO4)2 Al(NO3)3 Fe(OH)2 Hg2(SCN)2 Mg(HCO3)2 Al2(C2O4)3
Naming compounds with polyatomics • positive ion always written first • if (+)’ve ion is a metal - check if more than one oxidation state - if > 1 need roman numeral in name • if (–)’ve ion is polyatomic - 2nd part name is name of polyatomic (don’t modify ending)
Name the following Sodium hydroxide • NaOH • KHCO3 • LiNO3 • CaSO4 • Al(NO3)3 • Fe(OH)2 • CuSO4 • CuSCN 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