1. Chemistry 3.2 Naming Ionic Compounds
Science 9

2. By the end of this lesson you should be able to…
Objectives
By the end of this lesson you should be able to…
Write the formulas for ionic compounds
Including compounds with multivalent and polyatomic ions
Write the names of ionic compounds

3. Ionic Compounds
All ionic compounds are composed of positive and negative ions
The positive ions are donating (or giving) their electrons to the negative ion.

4. Chemical Names
International Union of Pure and Applied Chemistry (IUPAC)
Represents chemists around the world
Came up with rules for naming

5. Naming Rules For Ionic Compounds
The first part of the name always comes from the positive ion
The metal
The second part of the name comes from the negative ion
The non-metal
Non-metals (negative ions) name always changed to an “ide” ending

6. Non-Metal Endings
Non-metals (negative ions) name always changed to an “ide” ending
Symbol
Name F-
fluoride
Cl-
chloride
Br-
bromide I-
iodide
O2-
oxide
S2-
selenide
N3-
nitride
P3-
phosphide

7. Naming Example
NaCl
The first part of the name always comes from the positive ion
The second part of the name comes from the negative ion
Non-metals (negative ions) name always changed to an “ide” ending
Sodium
Chlorine
Chloride

8. Naming Example
NaCl
The first part of the name always comes from the positive ion
The second part of the name comes from the negative ion
Non-metals (negative ions) name always changed to an “ide” ending
Sodium
Chlorine
Chloride

9. Practice AlI3 Na2O Mg3P2 CaSe AgI Aluminum iodide Sodium oxide
Magnesium phosphide
Calcium selenide
Silver iodide

10. Writing Formulas Rules
Hand out cut outs
Rules
In ionic compounds the positive charges balance out the negative charges
Get the symbols and their charges
Criss Cross the charges and delete the signs
You don’t need to write in 1’s

11. Writing Formulas Example Berylium and Nitrogen
Rules
In ionic compounds the positive charges balance out the negative charges
Get the symbols and their charges
Criss Cross the charges and delete the signs
Be N
Berylium: Be2+ Nitrogen: N3- 3- 2+
Be3N2

12. Important
The final formula must be in the smallest whole number ration
Ex. Sn O2- 4+ 2-
Sn O
Sn2O4
WAIT! Your not finished yet
SnO2

13. Practice Write the formulas of.. a) Lithium with Chlorine
b) Calcium with Fluorine
c) Sodium with Sulphur
d) Lithium fluoride
e) Silver sulphide
LiCl
CaF2
Na2S
LiF
Ag2S

14. MultiValent Metals Look at Iron (Fe) on your periodic table
What do you notice about it?
How would we write the formula for Iron and Clorine.
2 different charges +2 and +3 !
Would it be FeCl3 OR FeCl2

15. Solution We need to specify if we are talking about Fe3+ or Fe2+
We use Roman Numerals to name these multivalent atoms
The Roman Numeral tells us the charge on the metal.
Charge
Roman Numeral 1+ I 2+ II 3+
III 4+ IV 5+ V 6+ VI 7+
VII

16. Naming with Multi-Valent Ions
The first part of the name always comes from the positive ion
The metal
Put the roman numeral for the charge in brackets after you name the metal.
The second part of the name comes from the negative ion
The non-metal
Non-metals (negative ions) name always changed to an “ide” ending

17. Naming with Multi-Valent Ions
ex. FeCl3
The first part of the name always comes from the positive ion
iron
Put the roman numeral for the charge in brackets after you name the metal.
Charge is Roman numeral III
The second part of the name comes from the negative ion
Chlorine
Non-metals (negative ions) name always changed to an “ide” ending
Chloride
Iron (III)

18. Naming with Multi-Valent Ions
ex. FeCl3
The first part of the name always comes from the positive ion
iron
Put the roman numeral for the charge in brackets after you name the metal.
Charge is Roman numeral III
The second part of the name comes from the negative ion
Chlorine
Non-metals (negative ions) name always changed to an “ide” ending
Iron (III)
Chloride

19. Formulas with Multivalent ions
Rules are very similar
In ionic compounds the positive charges balance out the negative charges
Get the symbols and their charges
For the multivalent ion use the charge given in the brackets
Criss Cross the charges and delete the signs
You don’t need to write in 1’s

20. Fe Cl Fe Cl Ex. Iron (III) Chloride Get the symbols and their charges
For the multivalent ion use the charge given in the brackets
Criss Cross the charges and delete the signs
You don’t need to write in 1’s 3+ _ Fe Cl 3+ 1- Fe Cl
Formula is FeCl3

21. Polyatomic Ions Found on your periodic table
Always paired up with ions that have the opposite charge
They contain covalent bonds but have an overall charge
You do not need to memorize these since they are on your periodic table!

22. Naming Polyatomic ions
Follow the same naming rules as before
Make sure you name the positive ion THEN the negative ion
But do not change the endings of the polyatomic ions
Keep the name as it is written on the periodic table

23. Formulas for polyatomic ions
BRACKETS, BRACKETS, BRACKETS
When writing a formula that includes a polyatomic ion, if there is a subscript (little number next to the polyatomic ion) you must use brackets
Examples on the board

24. Your Turn Finish naming and formula practice page
Work on mixed up naming worksheet