Ionic Compound Formulas and Naming for Multivalent Metals Notes
What does multivalent mean?
 Some transition metals are multivalent
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This means they have more than one ion form
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Look at the periodic table (textbook) and locate some multivalent transition metals
The most common ion is listed first
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What is the most common ion for Cu? , Au?
Writing names for multivalent ions
•We need to distinguish between the two or three different ion forms
•Use roman numerals from I – VII which corresponds to 1+ - 7+ ion charges
•For example:
–Nickel can have two ion forms, Ni2+ and Ni3+
–These are named nickel (II) and Nickel (III)
Writing formulas for compounds containing a multivalent metal
•There will only be 1 multivalent metal in a compound
•It is the metal so it is first in the name (same as ionic compounds)
•The roman numeral will indicate which ion form is in the compound
***If you are not told what the charge is on the metal with more than one charge, assume it is the most common
charge. (charge on top)***
Steps for writing formulas for multivalent compounds
•Step 1: Identify each ion and its charge
•Step 2: Determine the total charges needed to balance positive and negative
•Step 3: Note the ratio of positive ions to negative ions
•Step 4: Use subscripts to write the formula, 1’s are not shown in subscript
Try the formula for
titanium (IV) fluoride
manganese (III) sulfide
Compound Naming
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To name metals with more than one charge we use the Stock system.
In the Stock system, the charge of the metal is indicated by a Roman numeral written after the name of the
metal.
o Fe2O3 - iron(III) oxide
o FeO - iron(II) oxide
o PbO2 - lead(IV) oxide
The Stock system should not be used for metals that have only one possible charge.
Steps for Writing names for formulas for compounds that contain a multivalent metal (stock system)
•Step 1: Identify a multivalent metal
•Step 2: identify its different ion forms
•Step 3: determine the ratio of ions in the formula
•Step 4: what is the charge on the negative ion?
•Step 5: Balance the positive and negative charges
•Step 6: Write the name using roman numerals in brackets, following the positive ion to indicate which ion was
used
Example: FeI2
Example: PbF4