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Writing the Formulas of Ternary Ionic Compounds. By: Nick Cox, Cady Conrad and Zoë Greening. A Ternary compound is one that has three or more elements involved in the compound.
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Writing the Formulas of Ternary Ionic Compounds By: Nick Cox, Cady Conrad and Zoë Greening
A Ternary compound is one that has three or more elements involved in the compound. • These ionic compounds will have one or more polyatomic ions. These are ions that have two or more elements clustered together with a charge assigned to the cluster. • Ex. Carbonate ion (CO3-2), Phosphate (PO4-3), Acetate (C2H3O2-) and Chromate (CrO4-2).
The rules for writing the formulas of ternary ionic compounds are pretty much the same as for binary compounds except you will be using polyatomic ion names. • One other thing to keep in mind is that if you have more than one polyatomic ion to indicate in the formula, you group the polyatomic ion in a set of parenthesis and then place the number of those ions on the outside of the parenthesis as a subscript. If you have only one polyatomic ion to indicate in the formula you do not use the parenthesis
What is the formula for Iron III Carbonate? • Identify the symbol of the cation (first part of the name) and the anion The symbol for Iron is Fe and the symbol for Carbonate which is a polyatomic ion is CO3 • Identify the valence or charge of each symbol and place it in parenthesis just above the symbol The valence for Iron III is +3 and the valence for Carbonate is -2
Balance the total positive and negative charge on the cation and anion. We must have the same number of positive charges as we do of negative charges. Since an Iron III has a +3 charge and the Carbonate ion has a -2 then it would take two Fe+3 units to balance three CO3-2 units • Once you have determined the number of units of the cation and anion those become the subscripts which are placed right after the respective symbol. • Fe2(CO3)3
What is the name of Be(HSO3)2 ? • Identify the element name of Be which would be Beryllium • Identify the HSO3 which is Hydrogen Sulfite • Add the two together for the name • Beryllium Hydrogen Sulfite
What is the name of Fe(OH)2 ? • Identify the element name of Fe and recognize that Iron can have more than one valence. • Determine the valence. 1(x) + 2(-1) = 0 x - 2 = 0 x = 2 • Identify the name of the OH which would be Hydroxide • Add the two together identifying the valence for Fe • Iron(II) Hydroxide
Questions Write the formulas for the following: • Tin II Hydrogen sulfate • Magnesium Acetate • Aluminum Hydroxide • Sodium Sulfate • Copper II Phosphate • Lithium Sulfite
More Questions Name the following: • PbSO4 • Sn(C2H3O2)4 • Al2(SO4)3 • BaCrO4 • K3PO4