1. Lesson 12: Ionic Compounds & Formulas and Naming for Multivalent Metals

2. What does multivalent mean?
Compounds with multivalent metals are written with Roman numerals in the chemical name (ie. manganese (IV) oxide)
Multivalent – metals that form ions in more than one way
The Roman Numeral tells you two things:
The metal can form ions with different charges
The charge on the metal ion.
The most common ion is listed first
Look at your periodic table.
(What is the most common ion for Cu? Au?)

3. What is the arrow pointing at?

4. What are multivalent ions?
It’s pointing at Copper which is a multivalent metal.
Copper has 2 ion forms
It forms a 1+ or 2+ ion
Copper I Chloride
Copper II Chloride

5. Roman Numerals
Use roman numerals from I – VII which corresponds to ion charges
Metal Ion Charge
Roman numeral +1 I +2 II +3
III +4 IV +5 V +6 VI +7
VII

6. Roman Numerals
Use roman numerals from I – VII which corresponds to ion charges
For example:
Nickel can have two ion forms, Ni2+ and Ni3+
These are named nickel (II) and Nickel (III)

7. Steps for writing formulas for multivalent compounds
Step 1: Identify each ion and its charge
Example: Iron (III) bromide
Fe Br -

8. Steps for writing formulas for multivalent compounds
Step 2: Use subscripts to write the formula
(use the same swap and drop method)
Example: Fe Br -
FeBr3

9. Steps for writing formulas for multivalent compounds
Step 3: Double Check - does the total number of (+) and (-) ions in the compound balance to zero?
FeBr3
1Fe3+ : +3
3Br-: -1, -1, -1

10. Try the formula for titanium (IV) nitride
Ti4+ and N3-

11. Steps for writing formulas for multivalent compounds
Step 1: Identify each ion and its charge
Example: Titanium (IV) nitride
Ti N3-

12. Steps for writing formulas for multivalent compounds
Step 2: Use subscripts to write the formula
(use the same swap and drop method)
Example: Ti N3-
Ti3N4

13. Steps for writing formulas for multivalent compounds
Step 3: Double Check - does the total number of (+) and (-) ions in the compound balance to zero?
Ti3N4
3Ti4+ :
4N3-: -3, -3,

14. Writing formulas for compounds that contain a multivalent metal
Key Points to remember:
The metal is always first
The metal is always the positive ion
The metal could be a multivalent metal
Go to the periodic table and check

15. Steps for Writing formulas for compounds that contain a multivalent metal
Step 1: Identify a metal and its charge from the periodic table.
Example:
Cu2S
Metal is Cu.
Cu can be Cu+2 or Cu+1

16. Steps for Writing formulas for compounds that contain a multivalent metal
Step 2: Determine the ratio of ions in the formula
Example:
Cu2S
This formula means there are 2 copper ions for every 1 sulphide ion:
2 Cu : 1 S

17. Steps for Writing formulas for compounds that contain a multivalent metal
Step 3: Note the charge of the (-) ion from the periodic table
Example:
Cu2S
Sulphur has a charge on 2-

18. Steps for Writing formulas for compounds that contain a multivalent metal
Step 4: Choose the charge from the (+) ion that balances out the formula
Example: Cu2S
2 Cu: ____ ____
1S: 2-
What charge for Cu should we use +1 or +2 ?

19. Steps for Writing formulas for compounds that contain a multivalent metal
Step 4: Choose the charge from the (+) ion that balances out the formula
Example: Cu2S
2 Cu:
1S: 2-
That’s right - we should use the 1+ charge as that balances the charges to zero

20. Steps for Writing formulas for compounds that contain a multivalent metal
Step 5: Write the name of the compound
Example: Cu2S
2 Cu:
1S: 2-
Since we used the 1+ charge the name of the compound is: copper (I) sulphide

21. Your turn to try some…..
complete the problems in your note package as well as the one’s in the booklet given out.