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.

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. https://www.youtube.com/watch?v=p9iQ5Qn42DM Then work out the formula of the following compounds. The answers will come when you ‘click’

Straightforward formulae first

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

zinc oxide Zn2+ O2- What are the ions? What is the formula? ZnO

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

magnesium sulfide Mg2+ S2- What are the ions? What is the formula? MgS

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

Now for some slightly more challenging formulae

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

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

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

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

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

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

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

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

Now lets add some examples when complex ions are needed.

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

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

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

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

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

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

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

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

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

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

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.

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

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

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

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

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

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

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

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