2 ElementsElements are the simplest substances. There are about 100 different elementsNSOCFeKEach elements has just one particular type of atom that is different to the atoms in any other elementNEven in elements atoms usually join (bond) together.In some elements atoms bond to form small simple structures.In other elements atoms bond into giant structures with millions of atoms.
3 Water – a simple structure DNA – a large & complex structure CompoundsCompounds are formed when different elements chemically react together.In these reactions different types of atom become chemically bonded.Like elements some compounds have small simple structures with just a few atoms bonded togetherOther compounds have large, complex structures containing thousands or even millions of bonded atoms.OHWater – a simple structureDNA – a large & complex structure
4 Compounds are not just mixtures Reacting is different to just mixing.The physical and chemical properties of compounds are very different to their original elements.COMPOUNDELEMENTSCarbon oxygenCarbon dioxideCOCO(black solid)(colourless gas,that supportscombustion)(a colourless gas, that extinguishes fire)
5 Rust consists of iron combined with oxygen ActivityCopy the Table and fill in the last column.NameFormulaElement or compoundRust consists of iron combined with oxygenSodium chlorideNaClcompoundNickelNielementCopper sulphateCuSO4compoundWaterH2OcompoundOxygenO2elementRustFe2O3compoundMercuryHgelementSandSiO2compound
6 exist in layers (or shells) around the outside of the nucleus Bonding and atomsTo understand bonding we must know a little about the atoms from which elements are made.Atoms consist of three types of particles that are even smaller than atoms:Protons } These exist inNeutrons } the nucleus.Electrons }exist in layers (or shells) around the outside of the nucleus
7 No charge on element atoms Two of the three particles in atoms have an electrical charge.Protons Neutrons Electrons -1BUT atoms have equal numbers of protons and electrons. This means their overall charge = zero.For exampleFluorine9 protons 9+9 electrons 9-10 neutrons 0Total Charge 019F920Ne10Neon Copy & Fill in the gaps___ protons ______ electrons ______neutrons ___Total Charge ___1010+1010-10
8 Noble Gases: full shells The electrons around the outside of atoms are arranged in layers called shells1st Shell: electrons2nd Shell: electrons3rd Shell: electronsEach shell has a maximum number of electrons that it can hold.In noble gases the shells are completely full rather than partially full.During bonding other atoms try to attain the “full electron shell” structure of the noble gases.
9 Atoms can be joined together in 3 possible ways Types of bondingAtoms can be joined together in 3 possible waysMetal and non-metalNon-metals onlyMetals onlyIonic BondingCovalent BondingMetallic BondingAll three types involve changes in the electrons in the outermost electron shells of the atoms
11 IONIC BONDING Most ionic compounds contain a metal and a non-metal. When metals react they lose outer shell electrons to leave a full electron shell.This produces a charged atom (ion) with a + charge.Lose 1 or more electronsNeutral atomn+Positive ionWhen non-metals react with a metal they gain electrons to achieve a full electron shell.Gain 1 or more electronsNeutral atomn-Negative ion
12 Opposites attract – lattices The oppositely charged ions are attracted into a lattice that gets bigger and bigger until it consists of millions of ions+-+-+-+-+-oppositesattractAnd ion, and ion, and ion!
13 Lattices are 3-Dimensional We have shown ions attracting and building into a 2 dimensional sheet.+-In fact the whole process will be going on in three dimensions to build up a giant 3-D lattice.+-And so on to build a giant 3-D lattice with millions of ions.+-
14 Ions and electron structures Metals lose electrons to form positive(+) ions called cations.n+Non-metals gain electrons to form negative (–) ions called anions.n-We know that the atoms lose or gain electrons to achieve full electron shells.To understand more about how ionic compounds form we must look at what is happening to the outer shell electrons.
15 Formation of sodium chloride 1. Formation of sodium ions Sodium has 1 electron in its outer shell.If it loses this it will have no partially filled shells.NaNa+Loses 1 electronSodium atom (2.8.1)Sodium 1+ ion (2.8.0)This only happens if there is another atom able to accommodate the lost electron.
16 Formation of sodium chloride 2.Formation of Chloride ions Chlorine has 7 electrons in its outer shell.If it gains 1 electron it can achieve a full outer electron shell. It is, therefore, going to be able to accept the electron that the sodium wants to lose.ClClGains 1 electron(from sodium)Chlorine atom (2.8.7)Chlorine I - ion (2.8.8)
17 Formation of Sodium Chloride- the overall process. Sodium loses itsouter electron.Chlorine gains it.The result isboth end up withfull shellsClNaTwo oppositelycharged ionsare formed,which attract.Millions of such pairs form a giant latticeNaCl
18 Simpler electron diagrams We can assume full inner electron shells.We can therefore sometimes shorten bonding diagrams by omitting to draw the inner electron shells.NaClNaCl
19 Bonding in Magnesium Oxide More than one electron may be transferred between atoms in ionic bonding.OMg22.214.171.124.6Magnesium atomOxygen atomMg2+O2-2.8Magnesium Oxide
20 Draw a simplified bonding diagram (omitting inner shells) for magnesium oxide. MgOMagnesium atomOxygen atomMg2+O2-Magnesium Oxide
21 Copy the diagram and draw another box showing the electron configuration in sodium fluoride. Na126.96.36.199.7Sodium FluorideNa+F-Sodium atomFluorineatom2.82.8
22 Bonding in Lithium Oxide The bonding in lithium oxide is more complicated in that there are different numbers of each atom.LiOLi+O2-
23 Bonding in Lithium Nitride The bonding in lithium nitride similarly involves different numbers of each atom.LiLi+N3-LiN
24 Bonding in Aluminium Fluoride In aluminium fluoride it is the non-metal atoms that we need more of.AlFFAl
25 ActivityFollowing the previously shown slides draw bonding diagrams for the compounds formed from the following atoms:Lithium (2.1) and fluorine (2.7)Sodium (2.8.1) and sulphur (2.8.6)Magnesium (2.8.2) and sulphur (2.8.6)Magnesium (2.8.2) and fluorine (2.7)Aluminium (2.8.3) and nitrogen (2.5)Remember that the total number of electrons lost by the metal must equal the total number of electrons gained by the non-metal
26 Electrons Lost = Electrons Gained Both sodium chloride and magnesium oxide are simple ionic compounds.In both cases the metal and non-metal need to lose or gain the same number of electrons respectively.NaCl1 electronNa+Cl-2 electronsOMgO2-Mg2+This is not always the case.
27 Different numbers of electrons Consider the reaction of sodium with oxygen.Sodium (2.8.1) needs to lose 1 electron.Oxygen (2.6) needs to gain 2 electronsThis can only happen if there are two sodium ions formed for every one oxygen ion formed.NaONa+O2-1 electron per sodiumThe formula will be Na2O.
28 Different numbers of electrons Consider the reaction of magnesium with chlorine.Magnesium (2.8.2) needs to lose 2 electron.Chlorine (2.8.7) needs to gain 1 electronsWe need 2 chlorines for every one magnesium.ClMgMg2+Cl-2 electronsThe formula will be MgCl2
29 Charges on ionsWhen atoms form ions they aim to attain electron shells that are either completely full or completely empty.If we know the electron configuration of an atom we can usually work out how many electrons it must lose or gain to achieve a noble gas configuration.This will tell us the charge on its ion.
30 Charges and Metal ions 2.8.2 Mg2+ 2.8.3 Al3+ 2.1Li+ Metals usually lose electrons to empty this outer shell.The number of electrons in the outer shell is usually equal to the group number in the Periodic Table.For example,Mg2.8.2 Mg2+Al2.8.3 Al3+Li2.1Li+
31 Charges and non-metal ions Outer shells with 5 or more electrons usually gain electrons to fill up the outer shell.For example,Oxygen (2.6) gains 2 electrons to form O2-Chlorine (2.8.7) gains 1 electron to form Cl-ClO2.62.8 O O2-2.8.7 Cl Cl-
32 ActivityCopy out and fill in the Table below showing what charge ions will be formed from the elements listed.HHeLiNaKBeScTiMgVCrMnFeCoNiCuZnGaGeSeBrCaKrAlPNOSClFNeArSiBCAsNaChargeOuter electronsNeBrOAlKCaClNLiSymbol15723681+3-1-2+3+2-
33 The formulae of ionic compounds This is most quickly done in 5 stages.Remember the total + and – charges must =zeroFor example, the formula of calcium bromide.Symbols: Ca BrCharge on ionsNeed more of BrRatio of ions 1 2Formula CaBr2Ca2+Br-BrCa2 electrons
34 The formulae of ionic compounds For example, the formula of aluminium bromide.Symbols: Al BrCharge on ionsNeed more of BrRatio of ions 1 3Formula AlBr3Al3+Br-BrAl3 electrons
35 The formulae of ionic compounds For example, the formula of aluminium oxide.Symbols: Al OCharge on ionsNeed more of ORatio of ions 2 3 (to give 6 e-)Formula Al2O3Al3+O2-OAl2e-
36 Activity Metals: Li Ca Na Mg Al K Non-Metals: F O N Br S Cl Using the method shown on the last few slides, 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 KNon-Metals: F O N Br S Cl
37 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 presentChargeFormulaIon2-1-1+CO32-OH-NH4+SO42-NO3-carbonatehydroxideammoniumsulphatenitrateNOSHC
38 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 ionsNeed more of neitherRatio of ions 1 1Formula LiNO3
39 More Complicated Formulae What is the formula of magnesium nitrate?Symbols: Mg NO3-Charge on ionsNeed more of NO3-Ratio of ions 1 2Formula Mg(NO3)2The 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.
40 More Complicated Formulae What is the formula of sodium sulphate?Symbols: Na+ SO42-Charge on ionsNeed more of Na+Ratio of ions 2 1Formula Na2SO4No brackets here as only one SO42- ion needed.Note although Na contains 2 letters it only represents a single atom – so no brackets!
41 Write down how to work out the formula of aluminium hydroxide. Symbols:Charge on ionsNeed more ofRatio of ionsFormulaAl3+OH-3+1-OH-13Al(OH)3Again we need brackets as 3 complete OH- ions are needed meaning that for each aluminium there are 3 oxygens and 3 hydrogens.
42 Write down how to work out the formula of ammonium sulphate. Symbols:Charge on ionsNeed more ofRatio of ionsFormulaNH4+SO42-1+2-NH4+21(NH4)2SO4Again we need brackets as 2 complete NH4+ ions are needed meaning that for each sulphate ion there are 2 nitrogen and 8 hydrogens.
43 Need to get total charge =6 Write down how to work out the formula of aluminium sulphate.Symbols:Charge on ionsNeed more ofRatio of ionsFormulaAl3+SO42-3+2-Need to get total charge =623Al2(SO4)3No 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.
44 Copy this choosing words from below to fill the gaps. loselatticeselectronsgainmetalFormed 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 _____.metallosegainelectronslattices.
45 Which of the following will have ionic bonding? Copper chlorideIronBrassSulphur dioxide
46 Which of the following is NOT true of ionic bonding? Metal ions have a + chargeNon-metal ions have a - chargeThey form a 2 dimensional latticeThey have giant structures
47 Which of the following is true about the oxide ion? Formed by oxygen atoms losing 2 electrons.Oxygen ions have an empty second shellExist in pairsHave a 2- charge16O8
48 Which of the following is true about the sodium ion? Has a 2,8,1 electron arrangementFormed by sodium atoms gaining 1 electron.Sodium ions have an empty second shellHave a 1+ charge23Na11
49 What formula compound will be formed from Mn4+ and O2- ions? Mn2O4MnO2Mn2OMnO4
50 What formula compound will be formed from Ga3+ and SO42- ions? Ga2(SO4)3Ga3(SO4)2Ga2S3O12Ga (SO4)3