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-

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 2+ 1- Need more of Br Ratio of ions 1 2 Formula CaBr2 Ca2+ Br- Br Ca 2 electrons

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

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

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

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

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 1+ 1- Need more of neither Ratio of ions 1 1 Formula LiNO3

More Complicated Formulae What is the formula of magnesium nitrate? Symbols: Mg NO3- Charge on ions 2+ 1- 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.

More Complicated Formulae What is the formula of sodium sulphate? Symbols: Na+ SO42- Charge on ions 1+ 2- 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!

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.

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.

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.

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.

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

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

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

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

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

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