1. Naming and Writing Formulas of Ionic Compounds
PAGE 238 – 241

2. Naming Binary Ionic Compounds
STEP 1: Name the METAL ion (unchanged)
STEP 2: Name the NON-METAL ion by changing it’s ending to –IDE.

3. Naming Binary Ionic Compounds
Calcium and Fluorine = Calcium Fluoride

4. Check your understanding
What is the name of the compound formed from these elements?
Lithium and oxygen
Magnesium and sulfur
Rubidium and bromine

5. Naming IONIC COMPOUNDS
Ionic compounds are named with the following rules:
The more positive element is written first.
Change the ending of the last element to ide.
Na2O
CaI2
BaF2

6. Naming IONIC COMPOUNDS
Ionic compounds are named with the following rules:
The more positive element is written first.
Change the ending of the last element to ide.
Na2O sodium oxide
CaI2 calcium oxide
BaF2 barium fluoride

7. Check your understanding
What is the name of the compound formed from these elements?
Lithium and oxygen Lithium oxide
Magnesium and sulfur Magnesium sulfide
Rubidium and bromine Rubidium bromide

8. WRITING CHEMICAL FORMULAS
In ionic compounds, every ELECTRON that is GIVEN by a metal must be ACCEPTED by a non-metal.
Even though ions have charges, when they form ionic bonds in a compound, the overall charge of the compound is NEUTRAL.

9. Writing Formulas of Ionic Compounds
When writing formulas of ionic compounds you must first DETERMINE THE CHARGES of the ions.
The Periodic Table lists ionic charge of each element

10. WRITING CHEMICAL FORMULAS
STEP 1: Determine the charges of each ion.
Eg. A compound of Calcium and Sulfur:
Calcium Ca 2+
Sulfur S 2-

11. WRITING CHEMICAL FORMULAS
STEP 2: Determine total number of charges needed to BALANCE the charges.
Ca S 2-
Total positive = Total negative = 2

12. WRITING CHEMICAL FORMULAS
STEP 3: Determine the LOWEST RATIO.
Ca S 2-
Total positive = Total negative = 2
2:2
1:1

13. WRITING CHEMICAL FORMULAS
STEP 4: Use SUBSCRIPTS to express the ratio. If only ONE element is needed, no subscript is used.
Ca S 2-
Total positive = Total negative = 2
2 : 2
1 : 1 Formula = CaS, not Ca2S2

14. Practice
Write the formula for a compound of Calcium and Chlorine.

15. Practice Write the formula for a compound of Calcium and Chlorine.
1. Determine the charges: Ca Cl-

16. Practice Write the formula for a compound of Calcium and Chlorine.
Determine the charges: Ca Cl-
Balance the charges: , 1- (need TWO chlorine to balance the charges)

17. Practice Write the formula for a compound of Calcium and Chlorine.
Determine the charges: Ca Cl-
Balance the charges: , 1-
Determine the ratio 1 calcium : 2 chlorine

18. Practice Write the formula for a compound of Calcium and Chlorine.
Determine the charges: Ca Cl-
Balance the charges: , 1-
Determine the ratio 1 calcium : 2 chlorine
Use subscripts CaCl2

19. Another One
Write the formula for a compound containing Aluminum and Sulfur
Step 1: Determine the charges Al 3+ S -2

20. Another One
Write the formula for a compound containing Aluminum and Sulfur
Step 1: Determine the charges Al 3+ S -2
Balance the charges 3, 3 : 2,2,2
6 6

21. Another One
Write the formula for a compound containing Aluminum and Sulfur
Step 1: Determine the charges Al 3+ S -2
Balance the charges 3, 3 : 2,2,2
6 6
Use subscripts Al2 S3

22. PRACTICE Lithium and Nitrogen Strontium and fluorine
Lanthanum and Nitrogen

23. PRACTICE Lithium and Nitrogen Li3 N Strontium and fluorine SrF2
Lanthanum and Nitrogen LaN

24. Homework
WB p46 in class

25. Naming and Writing Formulas of Multivalent Compounds

26. IONIC COMPOUNDS WITH MORE THAN ONE COMBINING CAPACITY
Some elements can have MORE THAN ONE ion charge.
They are said to be MULTIVALENT IONS
For example, iron can form two different ions:
Fe and Fe 3+

27. NAMING MULTIVALENT IONS
ROMAN NUMERALS tell us the CHARGE of the multivalent ion (not how many you need)
Cu 3+  
Fe  2+  
Mn   4+  

28. NAMING MULTIVALENT IONS
ROMAN NUMERALS tell us the CHARGE of the multivalent ion
Cu 3+  is called Copper (III)
Fe  2+                 Iron (II)
Mn   4+              Manganese (IV)

29. WRITING FORMULAS OF IONIC COMPOUNDS WITH MULTIVALENT IONS
STEP 1: Determine the charges.
STEP 2: Determine total charges needed to Balance.
Step 3: Note the ratio.
STEP 4: Use subscripts.

30. WRITING FORMULAS OF IONIC COMPOUNDS WITH MULTIVALENT IONS
Iron (III) and Sulfur

31. WRITING FORMULAS OF IONIC COMPOUNDS WITH MULTIVALENT IONS
Fe Sulfur -2
Total charges needed , , -2,-2
Need TWO Iron, THREE Sulfur
Formula is Fe2 S3

32. Practice Write the formula of: Iron (II) Chloride Cobalt (III) Bromide
Tin (IV) Chloride
Mercury (I) Arsenic

33. Practice
Write the formula of:
Iron (II) Chloride FeCl2
Cobalt (III) Bromide CoBr3
Tin (IV) Chloride Sn Cl4
Mercury (I) Arsenic Hg 3 As

34. NAMING IONIC COMPOUONDS WITH MULTIVALENT IONS
WORK BACKWARDS to find out the combining capacity of a multivalent element.
Remember, the ions must combine in a ratio that gives an overall neutral charge.
Example: FeCl2 Example: FeCl3

35. NAMING IONIC COMPOUONDS WITH MULTIVALENT IONS
Example: FeCl2 Example: FeCl3
Iron (II) Chloride Iron (III) Chloride

36. FeO
PbO2
MoN
Cu2S
Mn3P2
AuCl3

37. Molybdenum (III) nitride
FeO
 iron (II) oxide
PbO2
lead (IV) oxide
MoN
Molybdenum (III) nitride
Cu2S
 copper (I) sulfide
Mn3P2
Manganese (II) phosphide
AuCl3
  Gold (III) chloride
Roman Numerals can ONLY be used if the element has more than one combining capacity.
Roman Numerals can ONLY be used if the element has more than one combining capacity.

39. POLYATOMIC IONS

40. Polyatomic Ions
Some atoms come together in groups (like a package of atoms) and have a charge like an ion. These are called polyatomic ions.
Most polyatomic ions are negative and they behave like a single unit in a compound.
The most common positive polyatomic ion is: NH 4+
It behaves like a METALS in a compound.

41. Naming Compounds with Polyatomic ions
When naming, use the given name of the package:
Step 1: Name the cation (unchanged)
Step 2: Name the anion (polyatomic ion)
Eg. CaCO3

42. Naming Compounds with Polyatomic ions
When naming, use the given name of the package:
Step 1: Name the cation (unchanged)
Step 2: Name the anion (polyatomic ion)
Eg. CaCO3 Calcium Carbonate

43. Try these
NaNO3
K2 CrO 4
KOH
LiNO 2

44. Try these
NaNO3 Sodium Nitrate
K2 CrO 4 Potassium Chromate
KOH Potassium Hydroxide
LiNO 2 Lithium Nitrite

45. POLYATOMIC IONS
If more than one of the polyatomic ions is in the compound, BRACKETS are placed around it to keep it as a package and the subscript is written on the OUTSIDE of the bracket. 
The subscript refers to everything inside the brackets.
Example: Al2(CO3)3

46. POLYATOMIC IONS
Example: Al2(CO3)3
How many Oxygen in this formula?

47. POLYATOMIC IONS Example: Al2(CO3)3 How many Oxygen in this formula?
3 x 3 = 9 Oxygen
How many Aluminum?

48. POLYATOMIC IONS Example: Al2(CO3)3 How many Oxygen in this formula?
3 x 3 = 9 Oxygen
How many Aluminum? TWO
THREE carbon

49. More Practice
MgSO4
Ca(NO3)2
Li2SO3
Au2CO3

50. MgSO4 Magnesium Sulfate Ca(NO3)2 Calcium Nitrate
Practice
MgSO Magnesium Sulfate
Ca(NO3)2 Calcium Nitrate
Li2SO Lithium Sulfite
Au2CO Gold Carbonate

51. One positive Polyatomic Ion
NH Ammonium ion
NH4 Cl
Step 1: Name the cation first  in this case, keep the name of the polyatomic ion.
Step 2: Name the anion (change the ending to –ide).

52. One positive Polyatomic Ion
NH4 Cl
Ammonium Chloride

53. Writing Formulas using the Cross Over Method

54. The Cross-over Method
An easy way to write the formula of an ionic compound is to use the crossover method.
The ions must combine in a ratio that gives an overall neutral charge.
Magnesium bromide:

55. Practice Magnesium chloride Barium sulphide Sodium oxide
Barium sulphide
Sodium oxide
Calcium nitride
Potassium fluoride
Beryllium phosphide

56. Practice Magnesium chloride MgCl Barium sulphide BaS Sodium oxide Na2O
Calcium nitride
Ca3N2
Potassium fluoride
 KF
Beryllium phosphide
Be3P2

57. Write the formulas of the polyatomic compounds using the crossover method
Ammonium chloride
Magnesium hydroxide
Calcium chlorate
Calcium sulphate
Potassium nitrite
Lithium nitrate

58. Write the formulas of the polyatomic compounds using the crossover method
Ammonium chloride
 NH4Cl
Magnesium hydroxide
 Mg(OH)2
Calcium chlorate
 Ca(ClO3)2
Calcium sulphate
 CaSO4
Potassium nitrite
KNO2
Lithium nitrate
 LiNO3

59. Homework
Read text p
Answer CYU p 244 #1, 6, 10 a,b,d,e, 11 bcdf, 12abcd
WB page 46