Naming Multivalent Compounds

What are multivalent ions?

• Some transition metals can form more than one ion

• In other words some have more than 1 ion form

For Example: Copper has 2 ion forms Can be a 1+ or 2+ ion

Copper I Chloride Copper II Chloride

Writing Multivalent Compounds

Use roman numeral to show which ion form is present

Metal Ion charge Roman Numeral1+ I2+ II3+ III4+ IV5+ V6+ VI7+ VII

Ni2+ or Nickel II, is called Nickel two

Fe3+ or Ion III, is called Iron three

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

Example: Copper II Chloride

Cu2+ and Cl-

+2 = -1-1

ions

Total charge to balance

ratio 1 : 2

formula CuCl2

Example: Manganese IV Oxide

Mn4+ and O-2

+4 = -2-2

ions

Total charge to balance

ratio 1 : 2

formula MnO2

Steps for naming compounds that contain a

multivalent metal• Step 1: Identify the multivalent metal (first ion

written in formula• Step 2: verify that it has more than one ion form• Step 3: determine the ratio of ions in the formula• Step 4: what is the charge on the negative ion?• Step 5: what must be the charge on the positive

metal ion if it is to balance the negative ion• Step 6: write the name of the compound

Example: Au3N

ID the metal Au

Can it be in more than 1 ion form? Au+ and Au3+

Determine the ratio of ions in the formula Au3N 3 Au ions for every 1 N ion

Charge on the negative ion N3-

What does the charge on the metal have to be to balance the negative ion?

If there are 3 Au ions then the charge on Au must be 1+ to balance out N3-

The Name is: Gold(I)Nitride