1. Activity
Copy out and fill in the Table below showing what charge ions will be formed from the elements listed. H He Li Na K Be Sc Ti Mg V Cr Mn Fe Co Ni Cu Zn Ga Ge Se Br Ca Kr Al P N O S Cl F Ne Ar Si B C As Na
Charge
Outer electrons Ne Br O Al K Ca Cl N Li
Symbol 1 5 7 2 3 6 8 1+ 3- 1- 2+ 3+ 2-

2. The formulae of ionic compounds
This is most quickly done in 5 stages.
Remember the total + and – charges must =zero
For example, the formula of calcium bromide.
Symbols: Ca Br
Charge on ions
Need more of Br
Ratio of ions 1 2
Formula CaBr2
Ca2+
Br- Br Ca
2 electrons

3. The formulae of ionic compounds
For example, the formula of aluminium bromide.
Symbols: Al Br
Charge on ions
Need more of Br
Ratio of ions 1 3
Formula AlBr3
Al3+
Br- Br Al
3 electrons

4. The formulae of ionic compounds
For example, the formula of aluminium oxide.
Symbols: Al O
Charge on ions
Need more of O
Ratio of ions 2 3 (to give 6 e-)
Formula Al2O3
Al3+
O2- O Al
2e-

5. Activity Metals: Li Ca Na Mg Al K Non-Metals: F O N Br S Cl
Work out the formula of all the ionic compounds that you can make from combinations of the metals and non-metals shown below:
Metals: Li Ca Na Mg Al K
Non-Metals: F O N Br S Cl

6. More Complicated Formulae
Ionic compounds may contain ions consisting of groups of atoms rather than a single atom.
Here are some more complicated ions you may come across.
Atoms present
Charge
Formula
Ion 2- 1- 1+
CO32-
OH-
NH4+
SO42-
NO3-
carbonate
hydroxide
ammonium
sulphate
nitrate N O S H C

7. More Complicated Formulae
When working out formula you simply treat the entire group of atoms as though it were a single atom.
The only difficulty is to do with how we write down the final answer.
For example, what is the formula of lithium nitrate?
Symbols: Li NO3-
Charge on ions
Need more of neither
Ratio of ions 1 1
Formula LiNO3

8. More Complicated Formulae
What is the formula of magnesium nitrate?
Symbols: Mg NO3-
Charge on ions
Need more of NO3-
Ratio of ions 1 2
Formula Mg(NO3)2
The brackets around the NO3- ion show that the 2 refers to two complete NO3- ions.
It represents a total of 2 nitrogens and 6 oxygens with each magnesium ion.

9. More Complicated Formulae
What is the formula of sodium sulphate?
Symbols: Na+ SO42-
Charge on ions
Need more of Na+
Ratio of ions 2 1
Formula Na2SO4
No brackets here as only one SO42- ion needed.
Note although Na contains 2 letters it only represents a single atom – so no brackets!

10. Write down how to work out the formula of aluminium hydroxide.
Symbols:
Charge on ions
Need more of
Ratio of ions
Formula
Al3+
OH- 3+ 1-
OH- 1 3
Al(OH)3
Again we need brackets as 3 complete OH- ions are needed meaning that for each aluminium there are 3 oxygens and 3 hydrogens.

11. Write down how to work out the formula of ammonium sulphate.
Symbols:
Charge on ions
Need more of
Ratio of ions
Formula
NH4+
SO42- 1+ 2-
NH4+ 2 1
(NH4)2SO4
Again we need brackets as 2 complete NH4+ ions are needed meaning that for each sulphate ion there are 2 nitrogen and 8 hydrogens.

12. Need to get total charge =6
Write down how to work out the formula of aluminium sulphate.
Symbols:
Charge on ions
Need more of
Ratio of ions
Formula
Al3+
SO42- 3+ 2-
Need to get total charge =6 2 3
Al2(SO4)3
No brackets for Al as only one atom even though it’s 2 letters.
We do need brackets around the SO4 to show it is 3 complete sulphate ions.

13. Copy this choosing words from below to fill the gaps.
lose
lattices
electrons
gain
metal
Formed when a _____ and non-metal react.
Metals ___ electrons to empty their outer electron shell.
Non-metals _____ electrons to fill their outer electron shell.
The ratio of metal ions to non-metal ions will depend upon the number of ________ lost and gained.
The ions formed join up into giant _____.
metal
lose
gain
electrons
lattices.

14. Which of the following will have ionic bonding?
Copper chloride
Iron
Brass
Sulphur dioxide

15. Which of the following is NOT true of ionic bonding?
Metal ions have a + charge
Non-metal ions have a - charge
They form a 2 dimensional lattice
They have giant structures

16. Which of the following is true about the oxide ion?
Formed by oxygen atoms losing 2 electrons.
Oxygen ions have an empty second shell
Exist in pairs
Have a 2- charge 16 O 8

17. Which of the following is true about the sodium ion?
Has a 2,8,1 electron arrangement
Formed by sodium atoms gaining 1 electron.
Sodium ions have an empty second shell
Have a 1+ charge 23 Na 11

18. What formula compound will be formed from Mn4+ and O2- ions?
Mn2O4
MnO2
Mn2O
MnO4

19. What formula compound will be formed from Ga3+ and SO42- ions?
Ga2(SO4)3
Ga3(SO4)2
Ga2S3O12
Ga (SO4)3