Secondary 3 Chemical Bonding Notes - Pure Chemistry

Chemical BondingSyllabusLearningObjectives/ Notes 3.1IonicBonding (a)describetheformationofionsbyelectronloss/gainandthattheseionsusuallyhavetheelectronicconfigurationofanoblegas(b)describe,includingtheuseof‘dot-and-cross’diagrams,theformationofionicbondsbetweenmetalsandnon-metals,e.g.NaCl;MgCl2 (c)statethationicmaterialscontainagiantlatticeinwhichtheionsareheldbyelectrostaticattraction,e.g.NaCl(studentswillnotberequiredtodrawdiagramsofioniclattices)(d)relatethephysicalproperties(includingelectricalproperty)ofioniccompoundstotheirlatticestructure(seealso3.4(g)) 3.2Covalent Bonding (a)describetheformationofacovalentbondbythesharingofapairofelectronsandthattheatomsinthemoleculesusuallyhavetheelectronicconfigurationofanoblegas(b)describe,using‘dot-and-cross’diagrams,theformationofcovalentbondsbetweennonmetallicelements,e.g.H2 ;O2 ;H2 O;CH4 ;CO2 (c)deducethearrangementofelectronsinothercovalentmolecules(d)relatethephysicalproperties(includingelectricalproperty)ofcovalentsubstancestotheirstructureandbonding(seealso3.4(g)) 3.3MetallicBonding (a)describemetalsasalatticeofpositiveionsina‘seaofelectrons’(b)describethegeneralphysicalpropertiesofmetalsassolidshavinghighmeltingandboilingpoints,malleable,goodconductorsofheatandelectricityintermsoftheirstructure(seealso3.4(g)) 13.4StructureandPropertiesof Materials (b)describeanalloyasamixtureofametalwithanotherelement,e.g.brass;stainlesssteel(c)identifyrepresentationsofmetalsandalloysfromdiagramsofstructures(d)explainwhyalloyshavedifferentphysicalpropertiestotheirconstituentelements(e)comparethestructuresofthefollowingsubstancesinordertodeducetheirproperties:(i)simplemolecularsubstances,e.g.methane,iodine(ii)macromolecules,e.g.poly(ethene)(iii)giantcovalentsubstances,e.g.sand(silicondioxide),diamond,graphite(seealso3.4(g))(f)comparethebondingandstructuresofdiamondandgraphiteinordertodeducetheir

propertiessuchaselectricalconductivity,lubricatingorcuttingaction(studentswillnotberequiredtodrawthestructures)(g)deducethephysicalandchemicalpropertiesofsubstancesfromtheirstructuresandbondingandviceversa(seealso3.1(d),3.2(d),3.3(b)and3.4(e)) 4.1FormulaeandEquationWriting (a)statethesymbolsoftheelementsandformulaeofthecompoundsmentionedinthesyllabus(c)deducetheformulaeofsimplecompoundsfromtherelativenumbersofatomspresentandviceversa(d)deducetheformulaeofioniccompoundsfromthechargesontheionspresentandviceversa 2IonicBonding 1. Formationof IonsBigidea1: TheStableElectronicConfigurationof aNobleGas 1.TheelementsfoundinGroup0ofthePeriodicTableareknownasnoblegases.Someexamplesofthenoblegasesarehelium,neon,argon,krypton,xenonandradon. 2.Noblegasesarestableandunreactive.Theyaremonatomicandexistassingleatoms.

3.Noblegasesarestablebecausetheyhavefullyfilledoutershells.Heliumhasadupletconfigurationwhileallothernoblegaseshaveanoctetconfiguration.(thusareinert anddonotreactwithotheratoms.) 4.Atomsofotherelementsarereactivebecausetheiroutershellsarenotfullyfilled.Theseatomslose,gainorshareouterelectronstoachievecompletevalencesh