1. Ionic Compound Nomenclature
Vocabulary
polyatomic ion
multivalent
“Olympic Pieces”, Banksy, British, 2012

2. Why do we need names for people?

3. Why do we need names for compounds?

4. So how do we name ionic compounds?
It’s easy! Name each of the ions in the compound. There’s just a couple of things to keep in mind.

5. Rule #1
Name the cation first and the anion second (just like they are in the formula).

6. Rule #2
If the anion is an element, change the ending of the element to “-ide.” Examples: chlorine becomes chloride phosphorous becomes phosphide

7. Rule #3
If the anion is a polyatomic ion, do not change its name. (The polyatomic ions are listed on your polyatomic ion sheet. If you have lost yours, you can download a new one on my website.)

8. Polyatomic Ion Sheet

9. Rule #4
If the cation can have more than one charge (if it is multivalent), use a Roman numeral to indicate the charge of the cation. (These are generally the transition metals and tin and lead. There are some exceptions we’ll look at later.)

10. Transition metals with tin and lead2+ 1+

11. Practice #1 Name the following ionic compound: NaCl
Rule #1: sodium chlorine
Rule #2: sodium chloride
Rule #3: N/A
Rule #4: N/A
So the compound is sodium chloride

12. Practice #2 Name the following ionic compound: Al2O3
Rule #1: aluminum oxygen
Rule #2: aluminum oxide
Rule #3: N/A
Rule #4: N/A
So the compound is aluminum oxide

13. Practice #3 Name the following ionic compound: Na2SO4
Rule #1: sodium sulfate
Rule #2: N/A
Rule #3: sodium sulfate
Rule #4: N/A
So the compound is sodium sulfate

14. Practice #4 Name the following ionic compound: Ca3(PO3)2
Rule #1: calcium phosphite
Rule #2: N/A
Rule #3: calcium phosphite
Rule #4: N/A
So the compound is calcium phosphite

15. Practice #5 Name the following ionic compound: FeCl2
Rule #1: iron chlorine
Rule #2: iron chloride
Rule #3: N/A
Rule #4: this one applies this time because iron is a transition metal and can have multiple charges (it’s multivalent), so let’s take a closer look…

16. Multivalency
Most transition metals (and lead and tin) are multivalent (i.e., they can have more than one charge.) This is in contrast to the elements in groups 1, 2, and 13 which can only have one charge. Iron is a transition metal, so in order to correctly name this compound, we need to figure out what charge is on the iron cation.

17. Fe Cl2 Multivalency in FeCl2
So the compound was FeCl2. We don’t know the charge of Fe, but we do know the charge of Cl because it is a group 17 element.
Fe Cl2 1- ?+
Cation
Anion
Ion Charge
Number of Ions
Total Charge 1-

18. Fe Cl2 Multivalency in FeCl2
Because there are 2 chloride ions, we have a total negative charge of 2-.
Fe Cl2 1- ?+ x
Cation
Anion
Ion Charge
Number of Ions
Total Charge 1- 2 2-

19. Fe Cl2 Multivalency in FeCl2
Remember: Compounds MUST be neutral. So what must the total positive charge be to neutralize the 2- charge of the chloride ions?
Fe Cl2 1- ?+
Cation
Anion
Ion Charge
Number of Ions
Total Charge 1- 2
Always must add up to zero!! 2+ 2-

20. Fe Cl2 Multivalency in FeCl2
Since there is only one iron atom in this formula, the charge on iron must be 2+.
Fe Cl2 1- ?+
Cation
Anion
Ion Charge
Number of Ions
Total Charge 2+ 1- 1 2
Always must add up to zero!! 2+ 2-

21. Fe Cl2 Multivalency in FeCl2
So in the name, we will use a Roman numeral 2 to indicate the charge of iron.
It is iron(II) chloride
Fe Cl2 1- 2+

22. Practice #5 Name the following ionic compound: FeCl2
Rule #1: iron chlorine
Rule #2: iron chloride
Rule #3: N/A
Rule #4: iron(II) chloride
So the name is iron(II) chloride

23. Practice #6 Name the following ionic compound: CrF3
Rule #1: chromium fluorine
Rule #2: chromium fluoride
Rule #3: N/A
Rule #4: chromium(III) fluoride
So the name is chromium(III) fluoride

24. Practice #7 Name the following ionic compound: Cu3P
Rule #1: copper phosphorous
Rule #2: copper phosphide
Rule #3: N/A
Rule #4: let’s look at this one more closely

25. Practice #7 (Cu3P)
Copper is a transition metal so we need to determine its charge in this compound. We don’t know copper’s charge, but we do know phosphorous’ charge because it is in group 15. ?+ 3-
Cu3 P x
Cation
Anion
Ion Charge
Number of Ions
Total Charge 3- 1 3-

26. Practice #7 (Cu3P)
You might think that copper will be 3+ to cancel out the 3- charge. But no. Remember there are 3 ions of copper in this compound that add up to 3+. ?+ 3-
Cu3 P
Cation
Anion
Ion Charge
Number of Ions
Total Charge 3- 3 1 3+ 3-

27. Cu3 P Practice #7 (Cu3P) So what is the charge on each copper ion? 1+
So we will name this copper(I) phosphide ?+ 3-
Cu3 P
Cation
Anion
Ion Charge
Number of Ions
Total Charge 1+ 3- 3 1 3+ 3-

28. Practice #8 Name the following ionic compound: Ni2(C2O4)3
Rule #1: nickel oxalate
Rule #2: N/A
Rule #3: nickel oxalate
Rule #4: nickel is a transition metal, so let’s look at this more closely

29. Practice #8
We don’t know nickel’s charge, but we do know oxalate’s charge. By using oxalate’s charge we can determine nickel’s charge. Ni2(C2O4)3 ?+ 2-

30. Practice #8
First we need to figure out the total negative charge.
What is the charge on oxalate (the anion)?
How many oxalate ions are there?
So what is the total negative charge? ?+ 2-
Ni2(C2O4)3 x
Cation
Anion
Ion Charge
Number of Ions
Total Charge 2- 3 6-

31. Practice #8
Now let’s figure out information about the cation, nickel.
Because the compound must be neutral, what is the total positive charge in the compound?
How many nickel ions are there?
So what is the charge on each nickel ion? ?+ 2-
Ni2(C2O4)3
Cation
Anion
Ion Charge
Number of Ions
Total Charge 2- 2 3
Always must add up to zero!! 6+ 6-

32. Practice #8
Now let’s figure out information about the cation, nickel.
Because the compound must be neutral, what is the total positive charge in the compound?
How many nickel ions are there?
So what is the charge on each nickel ion? 3+ 2-
Ni2(C2O4)3
Cation
Anion
Ion Charge
Number of Ions
Total Charge 3+ 2- 2 3
Always must add up to zero!! 6+ 6-

33. Practice #8 Ni2(C2O4)3 It is nickel(III) oxalate.
So now that we know the charge on each nickel ion, we can name this compound.
It is nickel(III) oxalate. 2- 3+
Ni2(C2O4)3

34. Practice #9 Name the following ionic compound: TiO2
Rule #1: titanium oxygen
Rule #2: titanium oxide
Rule #3: N/A
Rule #4: titanium is a transition metal, so let’s look at this more closely

35. Practice #9
Ti O2 ?+ 2-

36. Practice #9 Ti O2 ?+ 2- x 2- 2 4- Cation Anion Ion Charge
Number of Ions
Total Charge 2- 2 4-

37. Practice #9 Ti O2 ?+ 2- 2- 1 2 Always must add up to zero!! 4+ 4-
Cation
Anion
Ion Charge
Number of Ions
Total Charge 2- 1 2
Always must add up to zero!! 4+ 4-

38. Practice #9 Ti O2 4+ 2- 2- 1 2 Always must add up to zero!! 4+ 4-
Cation
Anion
Ion Charge 4+
Number of Ions
Total Charge 2- 1 2
Always must add up to zero!! 4+ 4-

39. Practice #9 Ti O2 It is titanium(IV) oxide
So now that we know the charge on each nickel ion, we can name this compound.
It is titanium(IV) oxide 2- 4+
Ti O2