Variable charge metals
Ionic Compounds
Variable Charge Ions
• Some elements in the transition metals can
form more than one type of ion. Sometimes
they may lose 2, 3, 4 or even more electrons
in order to bond with another element.
• So these metals can form +2, +3 ,+4 etc
cations in one compound but have a different
charge in another compound. In order to tell
them apart we name them differently.
Writing the formula
• When given the name of the compound, the
Roman numeral after the metal tells us the
CHARGE of the metal.
• Copper II Chloride – means Cu+2 Cl-1
• Follow the same steps as before >>>>
1. Write out the charges
2. Criss-cross
3. Combine as a formula unit (get rid of charges on
top)
4. Simplify if needed
Multiple Oxidation States
“tin fluoride”
Tin is either 2+ or 4+ oxidation state.
tin (II) fluoride
tin (IV) fluoride
Sn2+
Sn4+
F1-
SnF2
tin (II) sulfide
Sn2+
S2-
Sn2S2
SnS
F1-
SnF4
B. To find the formula, given the name:
1. Write symbols for the two types of ions.
2. Balance charges to write formula.
Co
Sn
cobalt (III) chloride
Co3+
Cl1–
CoCl3
tin (IV) oxide
Sn4+
O2–
SnO2
tin (II) oxide
Sn2+
O2–
SnO
Lets Practice some –
1.
2.
3.
4.
5.
6.
7.
Lead (IV) oxide
Mercury (II) Chloride
Bismuth (III) sulfide
Iron (II) Bromide
Copper (II) Chloride
Titanium (III) phosphide
Lead (II) oxide
When naming….
You need to work backwards from the formula to find the
charge of the metal.
1. First write the charge (oxidation state) of the nonmetal
(Anion)
2. Multiply the charge by its subscript.
3. The charge (oxidation state) of your cation (metal)
multiplied by its subscript needs to equal this number.
4. Write the name of the compound as usual, then change
the charge of the metal into a roman numeral, put into
parentheses and put it after the name of the metal.
A. To name, given the formula:
1. Figure out charge on
cation.
2. Write name of cation.
3. Write Roman numerals
in ( ) to show cation’s charge.
4. Write name of anion.
Fe
Cu
Stock System
of nomenclature
FeO
iron
Fe?2+ oxide
O2–
Fe2O3
?3+ oxide
iron
Fe
Fe?3+ O2– O2– O2– iron (III) oxide
CuBr
?
1–
copper
Brbromide
Cu1+
copper (I) bromide
CuBr2
1– Br1–
copper
Cu?2+ Brbromide
copper (II) bromide
iron (II) oxide
Let’s practice
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•
•
•
•
1. FeCl3
2. CuO
3. Cr2O3
4. NiS
5. V2O5