1. Writing and Naming
Ionic compounds
(criss cross method)

2. Be Cl Rule 1: Write the symbol of the metallic element first.
Beryllium combines with Chlorine + 2 - 1
Be Cl
Rule 2:
Place the combining capacity of one element as a subscript of the other element.

3. Be Cl2 1 The formula becomes BeCl2
Rule 3: Leave subscripts with a value of 1 out.
Be Cl2 1
The formula becomes BeCl2

4. Rule 4: Reduce the subscripts when necessary by the greatest common factor.
Magnesium combines with Sulfur + 2 - 2
Mg S S Mg
Mg S

5. Potassium combines with chlorine
Magnesium combines with bromine
Calcium combines with oxygen
Sodium combines with nitrogen
Lithium combines with sulfur
KCl
MgBr2
CaO
Na3N
Li2S

6. Naming Ionic Compounds
Two general rules:
1. Write the full name of the metal ion first.
2. Name the non-metal ion dropping the last
part of the name and adding the suffix “ide”.
The naming of compounds is monitored and updated by the International Union of Pure and Applied Chemistry (IUPAC).

8. Potassium combines with chlorine
Magnesium combines with bromine
Calcium combines with oxygen
Sodium combines with nitrogen
Lithium combines with sulfur
KCl - Potassium Chloride
MgBr2 - Magnesium Bromide
CaO - Calcium Oxide
Na3N - Sodium Nitride
Lithium Sulfide

9. Total e- given by metals equals total e- taken by the non-metals
The metal is named first and the non-metal is named second.
The non-metal always changes end to an “ide”.
Crisscross method - combining capacity of one is the subscript of the other.
Reduce the numbers is possible (2, 4 = 1, 2)
Total e- given by metals equals
total e- taken by the non-metals

11. Transition metals can give away different numbers of electrons.
To avoid confusion:
Brackets are used to show how many electrons the Transition metal is giving away.

12. Roman numerals tell combining capacity of Transition metals.
II 2
III 3
IV 4
V 5
VI 6
VII 7
VIII 8
IX 9
X 10

13. Fe Cl Fe Cl FeCl2 FeCl3 Iron (III) chloride Iron (II) chloride + 2 - 1

14. Write the formula for cobalt (III) oxide:+ 3 - 2
Co O
Co2O3

15. Write the Name: + - 1
Co Br
CoBr 3
Cobalt Bromide
(III)

16. Pb O PbO lead oxide (IV) Write the name of the ionic compound: +4 -2 +1
Pb O
PbO 2
lead oxide
(IV)

17. Write the name: +2 -2 + 1 - 1
Cu S
CuS
copper sulfide
(II)

18. 3. Lead (II) combines with sulfurPb S +2 -2 Pb S
lead (II) sulfide

19. Write the symbol of the metallic element first.
WRITING COMPOUNDS:
Write the symbol of the metallic element first.
Place the combining capacity of one element as a subscript of the other element.
Leave subscripts with a value of 1 out.
NAMING COMPOUNDS:
Write the full name of the metal ion first.
Name the non-metal ion dropping the last
part of the name and adding the suffix “ide”.
Brackets are used to show how many electrons the Transition metal is giving away.