Science 9: Chapter3 Elements combine to form compounds
Multivalent Metals
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Mutivalent metals are the metals that can form two or more different positive ions with different ion charges. The ion charges is called the
combining capacity of the ion.
Example: Iron Fe²⁺ Fe³⁺
Using periodic table to find out the combining capacities of the following metals
1
2
3
4
5
6
Metal
chromium
copper
mercury
tin
manganese
lead
Metal ions showing different combining capacities
To distinguish between two ions formed from multivalent atoms, the chemical name has a Roman numeral.
Example: iron (III) sulfide
The roman numeral
1. Tells us that the metal in the compound can form ion with different ion charges
2. Tells us the charge on the metal ion in that compound
Example: iron (III) sulfide, iron has an ion charge of 3⁺ in this compound-----------
Complete the following table
Roman numeral
I
II
III
Metal ion charge
1+
Roman numeral
V
VI
VII
Metal ion charge
Fe³⁺
Science 9: Chapter3 Elements combine to form compounds
IV
Rules for writing
FORMULAS of compounds containing multivalent metal
Steps
iron (III) sulfide
1. Identify metal ion
and its charge
2. Identify non metal
ion and its charge
3. Determine the
total charges
needed to balance
positive and
negative ions
Fe³⁺
4. Note the ratio of
positive ions to
negative ions
5. Use ratios as
subscripts to write
the formula
*Subscript “1” is
not shown in the
subscript
2 Fe³⁺ ions for
every 3 S²⁻
S²⁻
Fe³⁺: +3+3 = +6
S²⁻: -2-2-2=-6
Fe₂S₃
lead (IV) oxide
copper(I) sulfide manganese(IV)
oxide
tin (IV) nitride
Science 9: Chapter3 Elements combine to form compounds
Writing
NAMES of compounds containing multivalent metal (Rules on textbook page 90)
Steps
Cu₃P
1. Identify the metal
copper(Cu)
2. Verify that it can form
more than one kind of
ion by checking the
periodic table
Cu ⁺ Cu ⁺³
3. Determine the ratio of
ions in the formula
Cu₃P means 3 Copper ions
for every 1 phosphide ion
4. Note the charge of the
negative ion from the
periodic table
P³⁻
5. The positive and
negative charges must
balance out. Determine
what the charge needs
to be on the metal ion
to balance the negative
ion
Each of the three copper
ions must have a +1 charge
to balance the 1 phosphide
ion with a charge 3-.
Therefore, copper(I)
6. Write the name
compound
copper(I) phosphide
MnO₂
HgI₂
PbF₄
Science 9: Chapter3 Elements combine to form compounds
***DO Textbook Practice Problems Page 89 1.(a-n) and Page 90 1.(a-o)