1. Do not print out, just run through the slide show.
Christopher Whitehead Sixth Form: A-level Chemistry Summer Bridging Task
Do not print out, just run through the slide show.

2. How to work out chemical formulae
Watch the youtube clip to explain how
to work out the formula of a given
Compound – JUST WATCH THE FIRST
VIDEO CLIP.
Then work out the formula of the following compounds.
The answers will come when you ‘click’

3. Straightforward formulae first

4. lithium fluoride
Li F-
What are the ions?
What is the formula?
LiF

5. zinc oxide
Zn O2-
What are the ions?
What is the formula?
ZnO

6. sodium chloride
Na Cl-
What are the ions?
What is the formula?
NaCl

7. magnesium sulfide
Mg S2-
What are the ions?
What is the formula?
MgS

8. potassium iodide
K I-
What are the ions?
What is the formula? KI

9. Now for some slightly more challenging formulae

10. FeCl2 iron (II) chloride Fe2+ Cl- What are the ions?
What is the formula?
FeCl2
Fe2+ Cl-
Cl-

11. Cu2O cuprous oxide Cu+ O2- What are the ions? What is the formula?

12. Na2O sodium oxide Na+ O2- What are the ions? What is the formula?

13. MgBr2 magnesium bromide Mg2+ Br- What are the ions?
What is the formula?
MgBr2
Mg2+ Br-
Br-

14. K2S potassium sulfide K+ S2- What are the ions? What is the formula?

15. BaCl2 barium chloride Ba2+ Cl- What are the ions? What is the formula?

16. FeBr3 Iron (III) bromide Fe3+ Br- What are the ions?
What is the formula?
FeBr3
Fe3+ Br-
Br-

17. Fe2O3 Iron (III) oxide Fe3+ O2- What are the ions?
What is the formula?
Fe2O3
Fe3+ O2-
Fe3+ O2-
O2-

18. Now lets add some examples when complex ions are needed.

19. CaCO3 calcium carbonate Ca2+ CO32- What are the ions?
What is the formula?
CaCO3

20. sodium hydroxide
Na OH-
What are the ions?
What is the formula?
NaOH

21. AlPO4 aluminium phosphate Al3+ PO43- What are the ions?
What is the formula?
AlPO4

22. NH4NO3 ammonium nitrate NH4+ NO3- What are the ions?
What is the formula?
NH4NO3

23. ZnSO4 zinc sulfate Zn2+ SO42- What are the ions? What is the formula?

24. NaCH3COO sodium ethanoate Na+ CH3COO- What are the ions?
What is the formula?
NaCH3COO
Na+ CH3COO-

25. BaSO4 barium sulfate Ba2+ SO42- What are the ions?
What is the formula?
BaSO4
Ba2+ SO42-

26. CuSO4 copper (II) sulphate Cu2+ SO42- What are the ions?
What is the formula?
CuSO4

27. sodium hydrogencarbonate
Na HCO3-
What are the ions?
What is the formula?
NaHCO3
Na+ HCO3-

28. silver nitrate
Ag NO3-
What are the ions?
What is the formula?
AgNO3

29. Now lets add some examples when more than one complex ion are needed
Now lets add some examples when more than one complex ion are needed. Same rules apply but brackets are needed if more than one complex ion is required.

30. (NH4)2 O ammonium oxide NH4+ O2- What are the ions?
What is the formula?
(NH4)2 O
NH O2-
NH4+

31. (NH4)2 SO4 ammonium sulfate NH4+ SO42- What are the ions?
What is the formula?
(NH4)2 SO4
NH SO42-
NH4+

32. (NH4)3 PO4 ammonium phosphate NH4+ PO43- What are the ions?
What is the formula?
(NH4)3 PO4
NH PO43-
NH4+

33. Fe(OH)2 Iron (II) hydroxide Fe2+ OH- What are the ions?
What is the formula?
Fe(OH)2
Fe OH-
OH-

34. Fe(OH)3 Iron (III) hydroxide Fe3+ OH- What are the ions?
What is the formula?
Fe(OH)3
Fe OH-
OH-

35. Al(CH3COO)3 aluminium ethanoate Al3+ CH3COO- What are the ions?
What is the formula?
Al(CH3COO)3
Al3+ CH3COO-
CH3COO-

36. Al2(SO4)3 aluminium sulfate Al3+ SO42- What are the ions?
What is the formula?
Al2(SO4)3
Al SO42-
Al SO42-
SO42-

37. Ca3 (PO4)2 calcium phosphate Ca2+ PO43- What are the ions?
What is the formula?
Ca3 (PO4)2
Ca PO43-
Ca2+