1. Ionic Compounds: Naming and Formula Writing

2. Naming Compounds
Chemists have developed systematic ways to name compounds.
If you learn the naming rules, you can examine a compound’s formula and determine its name, and vice versa.
Many compounds also have a common name.
NaCl has the common name salt and the systematic name sodium chloride.

3. Oxidation Numbers
All compounds have an electrical charge of zero (they are neutral).
An oxidation number indicates the charge on the atom (or ion) when electrons are lost, gained, or shared in chemical bonds.

4. Naming Ionic Compounds
Identify if the metal cation has more than one potential charge.
Such metals are usually (but not always) found in the transition metals section of the periodic table.
Notable Exceptions:
Always Zn2+ and Ag+
Sn and Pb can have multiple charges

7. IONIC COMPOUNDS If charges cancel, just write the symbols
Na Cl NaCl
If charges do not cancel, criss-cross:
Ca Cl CaCl2
***Do not move the charge, only the number
***Do not write the 1

8. Binary Ionic Compounds
Binary compounds are those that contain only two different elements. The names for binary ionic compounds containing a metal that forms only one type of ion have the following form:
Name of Cation + Base Name of Anion + ide

9. Binary Ionic Compounds
Since the charge of the metal is always the same for these types of compounds, it need not be specified in the compound’s name.
Example: MgF2
Cation Name: Magnesium
Anion Name: Fluorine
Correct Anion Name: Fluoride
Complete Name: Magnesium Fluoride

10. Binary Ionic Compounds

11. Practice Name these compounds: CaO Al2O3 KF MgCl2 Li3N Calcium Oxide
Aluminum Oxide KF
Potassium Fluoride
MgCl2
Magnesium Chloride
Li3N
Lithium Nitride

12. Practice Write the formula for these ionic compounds:
Potassium bromide
KBr
Sodium oxide
Na2O
Zinc nitride
Zn3N2

13. Binary Ionic Compounds
If the cation could have more than one charge, then the charge must be specified in the metal’s name.
We specify the charge with a Roman numeral (in parentheses) following the name of the metal.

14. Binary Ionic Compounds
For example, we distinguish between Cu+ and Cu2+ by writing a (I) to indicate the 1+ ion or a (II) to indicate the 2+ ion:
Cu+ Copper(I)
Cu2+ Copper(II)

15. Binary Ionic Compounds
These compounds are named using the following form:
Name of Cation
(charge of metal in roman numerals)
Base Name of Anion + ide + +

16. Binary Ionic Compounds
We can determine the charge of the metal from the chemical formula of the compound.
The sum of all the charges must be zero.

17. Binary Ionic Compounds
What is the charge of iron in FeCl3? +3
How do we know?
Chlorine has a -1 charge and there are 3 of them
What is the name for FeCl3?
Iron (III) Chloride

18. Practice Name the following compounds:
PbCl4
Lead (IV) Chloride
PbO
Lead (II) Oxide
Explain why CaO is not named calcium (II) oxide.
Calcium has a +2 charge and oxygen has a -2 charge, so the charges already balance

19. Practice Write the formula for the following compounds:
Chromium (II) chloride
CrCl2
Tin (IV) oxide
SnO2
Iron (III) oxide
Fe2O3

20. Writing Formulas a Little Quicker
Simply cross the oxidation numbers and make them positive

21. Let’s try some more! Manganese (IV) Phosphide Manganese (IV) Oxide
Mn4+ + P3-  Mn3P4
Manganese (IV) Oxide
Mn4+ + O2-  Mn2O4  MnO2

22. Polyatomic Ionic Compounds
Ionic compounds containing polyatomic ions are named using the same procedure we apply to other ionic compounds, except that we use the name of the polyatomic ion whenever it occurs.

23. Polyatomic Ionic Compounds
For example, we name KNO3 using its cation, K+, potassium, and its polyatomic anion, NO3-, nitrate.
KNO3 potassium nitrate

24. Remember the Polyatomic Ions
NO31- Nitrate
SO42- Sulfate
PO43- Phosphate
OH1- Hydroxide
CO32- Carbonate
NH41+ Ammonium
What types of bonds occur in polyatomic ions?

25. Practice
Fe(OH)2
Iron Hydroxide
NH4NO3
Ammonium Nitrate

26. Practice Write the formula for the following compounds: barium nitrate
Ba(NO3)2
ammonium iodide
NH4I
iron (III) hydroxide
Fe(OH)3

27. Polyatomic Ionic Compounds
Many polyatomic ions are oxyanions, anions containing oxygen.
When a series of oxyanions contain different numbers of oxygen atoms, they are named systematically according to the number of oxygen atoms in the ion.

28. Polyatomic Ionic Compounds
If there are two ions in the series, the one with more oxygen atoms is given the ending -ate and the one with fewer is given the ending -ite.
NO3− nitrate SO42− sulfate NO2− nitrite SO32− sulfite

29. Polyatomic Ionic Compounds
If there are more than two ions in the series, then the prefixes hypo-, meaning “less than,” and per-, meaning “more than,” are used.
ClO − hypochlorite BrO − hypobromite ClO2− chlorite BrO2− bromite ClO3− chlorate BrO3− bromate ClO4− perchlorate BrO4−perbromate

30. Practice
K2CrO4
Potassium Chromate
Mn(NO3)2
Manganese Nitrate

31. Practice Write the formula for the following compounds:
sodium perchlorate
NaClO4
sodium chlorite
NaClO2
sodium nitrate
NaNO3
sodium nitrite
NaNO2