1. Multivalent Ionic Compounds

2. Multivalent Compounds
There are some elements on the periodic table that can form different Cations because of their valence electrons.
For example: Copper
It forms both Cu+ and Cu2+
You will also notice it has two names depending on the charge:
Copper (I) Cu+
Copper (II) Cu2+

3. Writing Formulas I 1 II 2 III 3 IV 4 V 5 VI 6 VII 7
We will be using the Stock system, the English name of element and the cation charge in Roman numerals
The Roman numeral tells you how many charges you are dealing with
Manganese (II) will have 2 charges! Mn2+ I 1 II 2
III 3 IV 4 V 5 VI 6
VII 7

4. Let’s Try!
Using the same Crossover method you have been taught, write the formula for Copper (II) Chloride.
Cu²+ and Cl-
Crossover Method =

5. Practice! Chromium (III) Phosphide Ruthenium (IV) Selenide
Palladium (II) Bromide
Iridium (III) Sulfide
Gold (I) Nitride
Copper (I) Oxide
Copper (II) Oxide
CrP
RuSe2
PdBr2
Ir2S3
Au3N
Cu2O
CuO

6. Naming
If the metal is a multivalent ion you will need to figure out the Roman Numeral based on the formula!
Example
Name CoI2
Answer - Cobalt (II) Iodide

7. This is How!! – YES YOU HAVE TO MATH
Multiply the charge on the anion by the number of anions and then divide by the number of cations to get the roman numeral.
Write the names for Fe2S3 SnO2

8. Fe2S3 S²- 3x2 = 6 6/2 = 3 Roman Numeral is (III) Answer
Iron (III) Sulfide

9. SnO2 O²- 2x2 = 4 4/1 = 4 Roman Numeral is (IV) Answer Tin (IV) Oxide
AND THAT IS WHY YOU CAN’T JUST FLIP BACK!

10. Practice CrF3 TiO2 AuCl3 Fe2O3 FeCl2 PdTe Os2O3
Chromium (III) Fluoride
Titanium (IV) Oxide
Gold (III) Chloride
Iron (III) Oxide
Iron (II) Chloride
Palladium (II) Telluride
Osmium (III) Oxide