C2 Topic 1 and 2

C2.1 Mendeleev • Mendeleevcreatedtheperiodictablein1871.• Hearrangedelementsinorderoftheirproper:es.•  -groups=down.•  -period=across

• Metalsareonthele?handsideoftheperiodictable.

Hearrangedthembythefollowingproper:es:

• Atomicmass• Density• Mel:ngPoint• Formulaoftheoxide

PaGernsemergeddownthegroupsandacrosstheperiodswhichconfirmedhispredic:ons.

C2.2 Structure of the atom

•  AtomsaremadeupofPROTONS,NEUTRONSandELECTRONS.

•  Theyarefoundintheposi:onsshownonthediagram.

•  Atomisthesmallestofpar:cles.

Electronshells

Nucleuscontainingprotonsandneutrons

Par0cle Rela0veMass

Rela0veCharge

Proton 1 +1

Neutron 1 0

Electron 1/1840 -1

Electronsfillshellsfromthemiddleintheorderof2,8,8,18(howmanyelementsareineachperiod)

Thegroupnumbercorrespondstothenumberofelectronsintheoutershell.

C2.3 The Modern Periodic Table •  Topnumber–MASSNUMBER

Thenumberofprotonsandneutrons

•  BoGomnumber–ATOMICNUMBERThenumberofprotons

(alsothesameaselectrons)

Al27

13

Protons=13Electrons=13Neutrons=27-13=14

Protonsandneutronsarepackedtogether0ghtlyinthenucleus(highdensity)

Electronsarespreadoutinshells(lowdensity)

Isotope-Elementswiththesamenumberofprotonsandelectronsbutdifferentnumberofneutrons.

C2.4 Electron shells

•  Electronlocatedintheshell.•  Electronicconfigura:on=howtheelectronsarearrangedinanatom.

C2.5 Ionic Bonding •  IonicbondsformbetweenMETALSandNON-METALS.•  IonicbondinginvolvesthetransferofELECTRONS.• MetallicIonsarePOSITIVELYcharged(ANIONS).• Non-metallicelementsareNEGATIVELYcharged(CATIONS). Loose

electron +

Common Ions Charged ParDcles.

Tobecomeposi:velychargedanatommustloseelectrons.Tobecomenega:velychargedandatommustgainelectrons.

C2.5 Ionic compounds- non metal and a metal. •  ConductelectricitywhenMOLTEN(melted)andinanAQUEOUSSOLUTION(dissolvedinwater)

•  DONOTconductelectricityasaSOLID•  HavehighMELTINGandBOILINGpoints

•  UsuallySOLIDatROOMTEMPERATURE

Ion=anatomwithaposi:veornega:vecharge.Ca:ons=metalatomsloseelectronstoformposi:velychargedionscalledca:ons.Anions=Non-metalatomsgainelectronstoformnega:velyionscalledanions.

Transferringelectrons=ionicbonds.

Ioniccompoundshavealaacestructure,witharegulararrangementofions,heldtogetherbyelectrosta:cforcesbetweenoppositelychargedions.

C2.6 Ionic compounds

•  Ioniccompoundscontainions.Belowaresomeofthecommonones.

Compoundions=containmorethanoneelement.Namesofioniccompounds=Ifthecompoundcontainsoxygenitendswithan–ate…..eg…..Ironsulfate=FeSO4Ifnooxygenthentheyendinan–ide…….IronSulfide….FeS

C2.7 ProperDes of ionic Compounds •  Solid=doesnotconductelectricity•  Liquid=conductelectricity…WHY….ionsarefreetomovearoundandtheyarecharged.• Mel:ngpoints=whenasubstancechangesfromsolidtoliquid.• Boilingpoint=changesfromaliquidtoagas.•  Ionicsubstances=highboilingpointsandhighmel:ngpoints.•  Ionicbonds=strongandlotsofthemtobreaksoneedslotsofenergy.

C2.8 Solubility Soluble=substancedissolves.Insoluble=doesnotdissolveSalt=Acid+alkaliTableexplainswhichsaltsaresolubleandwhicharenot.

2.10 PrecipitaDons. silvernitrate(soluble)+sodiumchloride(soluble)→silverchloride(insoluble)+sodiumnitrate(soluble)

AgNO3(aq)+NaCl(aq)→AgCl(s)+NaNO3(aq)

Precipita:onreac:on-Aninsolublesolidformedwhentwosolublesubstancesaremixed.

Bariumsulfateisusedasa‘bariummeal’tox-raypa:entsbecauseitis1.  Opaquetox-rays2.  Safetouse3.  Insolublesodoesn’tentertheblood

C2.10 Precipitates •  PrecipitatesareSALTSthatareformedinchemicalreac:onsthatDONOTDISSOLVEinthesolventusedinthereac:on.

C2.11 Ion Tests •  Iontestsformetals(ANIONS)areusuallydonebyFLAMETESTS.•  EachIONproducesacertainflamecolour.

Tes:ngforCATIONSisdonethroughchemicaltes:ng.1.  Chloride–addnitricacidandsilver

nitrate,ifawhiteprecipitateformsthenchlorideionsarepresent.

2.  Sulphate–addhydrochloricacidandbariumchloride,ifawhiteprecipitateformsthensulphateionsarepresent.

3.  Carbonate–addanacidandifthegasproducedturnslimewaterMILKYthecarbonateionswerepresent.(carbonatereleasecarbondioxide)

C2 Topic 3 & 4

C2.12 Covalent Compounds

Learnthesecovalentmolecules.Beabletodrawthemusingdotandcrossdiagrams.

Covalentbondiswhenapairofelectronsaresharedbetweentwoatomsformingamolecule.

MethaneCH4

WaterH2O

HydrogenH2CarbonDioxideCO2

HydrogenChlorideHClOxygenO2

C2.13 ProperDes of Covalent Substances

SimpleCovalentSubstances•  Lowmel:ngpoint•  Lowboilingpoint•  Poorconductorofelectricity

Why?•  Becausethereareweakforcesbetweenmolecules.

GiantCovalentSubstances• Highmel:ngpoint• Highboilingpoint

Why?• Becausetherearestrongforcesbetweenmolecules.

2.13 Diamond vs. Graphite

Diamond•  Usedtomakecuangtools.•  Veryhardwithstrongbondsbetweenmolecules.

•  Doesnotconductelectricitybecausetherearenofreeelectrons.

Graphite•  Usedtomakeelectrodesandlubricant.

•  Therearestrongforcesbetweenmoleculeswithinthelayers–butthereareweakforcesbetweenthelayers.

•  Thereisonefreeelectronforeachcarbonatommeaningitcanconductelectricity.

Bothexamplesofgiantcovalentmolecules.BothmadefromCARBON.

C2.15 Miscible or Immiscible? Keydefini0ons

Miscible–Liquidsthatcompletelymixtoformasolu:on.

Immiscible–Liquidsthatdonotformasolu:onbutseparateintotwolayerse.g.oilandwater.

Separa0ngtwoimmiscibleliquidsUseasepara:ngfunnel.1.  Openthetapandletthelowerliquidflowoutandcollectinabeaker.2.  Closethetapbeforetheupperliquidstartstorunout.3.  Changethebeakerandthenlettheotherliquidflowout.

Separa0ngtwomiscibleliquidsUsefrac:onaldis:lla:ontoseparateliquidairtoformnitrogenandoxygen.Exploitsthefacttheyhavedifferentboilingpoints.1.  Coolairto-200oCtoliquefyit.2.  Warmupto-185oCtoevaporatethenitrogenandkeeptheoxygenliquid.

C2.16 Chromatography Usedtoseparatemixturesofcolouredcompoundsincludinginks,dyesandcolouringagentsinfood.1.  AspotofthemixtureisplacedneartheboGomofapieceofchromatography

paperandthepaperisthenplaceduprightinasuitablesolvent,e.g.water.2.  Asthesolventsoaksupthepaper,itcarriesthemixtureswithit.3.  Differentcomponentsofthemixturewillmoveatdifferentrates.4.  Thisseparatesthemixtureout.RfvaluesDifferentchromatogramsandtheseparatedcomponentsofthemixturescanbeiden:fiedbycalcula:ngtheRfvalueusingtheequa:on:TheRfvalueofapar:cularcompoundisalwaysthesame-ifthechromatographyhasbeencarriedoutinthesameway.Thisallowsindustrytousechromatographytoiden:fycompoundsinmixtures.

Rf=distancemovedbythecompound÷distancemovedbythesolvent

C2.17 Chemical ClassificaDon

Typeofbonding

Mel0ngPoint BoilingPoint SolubilityinWater

Conduc0vity

Ionic High High MostDissolve Conductelectricitywhenmoltenorinsolu:on,notwhensolid

Simplemolecularcovalent

low low Somedissolveinwater

Donotconductelectricity

Giantmolecularcovalent

High High Insoluble Donotconductexceptgraphite

Metallic Highexceptmercury

Highexceptmercury

Insoluble Goodconductors

C2.14 Classifying Substances

Substance Mel0ngPoint BoilingPoint ElectricalConduc0vity

Solubilityinwater

TypeofBonding

SodiumChloride

High High Yesinsolu:onormolten

Soluble IONIC

MagnesiumSulfate

High High Yesinsolu:onormolten

Soluble IONIC

Hexane Low Low No Insoluble SIMPLECOVALENT

Paraffin Low Low No Insoluble SIMPLECOVALENT

Silicondioxide High High No Insoluble GIANTCOVALENT

Coppersulphate

High High Yesinsolu:onormolten

Soluble IONIC

Sucrose High High Soluble GIANTCOVALENT

Couldyouclassifythesesubstancesbasedontheirproper:es? Knowtheseexamples!

C2.18 Metallic Bonding and TransiDon Metals Thestructureofmetals–aregulararrangementofposi:veionssurroundedbyaseaofdelocalisedelectrons.

Metalsaremalleablebecauseionscanslideovereachotherifalargeenoughforceisapplied.Theelectronsholdtheionstogethermeaningthemetalspreadsoutratherthanbreaks.Metalsconductelectricitybecausethedelocalisedelectronsarefreetomove.Ifavoltageisapplied,theelectronsallmoveinthesamedirec:onandthisiscalledacurrent.

Mostmetalsaretransi:onmetalsandtheytypicallyhavehighmel:ngpointsandproducecolouredcompounds.

C2.19 Alkali Metals Alkalimetalsareso?withrela:velylowmel:ngpoints.Lithium,SodiumandPotassiumreactwithwatertoformhydroxides(whicharealkaline)andhydrogengas.

Alkalimetalsgetmorereac:veasyoumovedownthegroupsbecausetheatomslowerdownhavemoreelectronshells.Thismeanstheouterelectronisfurtherawayfromthenucleus,notheldinplaceasstrongly,andeasiertolose–makingitmorereac:ve.

Lithium+wateràLithiumHydroxide+HydrogenSodium+wateràSodiumHydroxide+HydrogenPotassium+wateràPotassiumHydroxide+Hydrogen

C2.20 Halogens

Halogen Colour Stateatroomtemperature

Fluorine PaleYellow Gas

Chlorine Green/yellow Gas

Bromine

Brown Liquid

Iodine Grey Solid

Metal+HalogenàMetalHalide

Potassium+BromineàPotassiumBromide2K(s)+Br2(l)à2KBr2(S)

Calcium+ChlorineàCalciumChloride

2Ca(s)+Cl2(l)à2KCl2(S)

Theyallfollowthesame

paGern.Learnthem.

C2.21 Displacement of the halogens • Displacementreac:ons–amorereac:veelementwilldisplace(taketheplaceof)alessreac:veelement.

PotassiumBromide+ChlorineàPotassiumChloridePotassiumChloride+BromineàNoreac:on

Chlorineismorereac:vethanbrominesowilldisplacethebromine.

SodiumIodide+ChlorineàPotassiumChlorideSodiumChloride+IodineàNoreac:on

Chlorineismorereac:vethaniodinesowilldisplacethe

iodine.

C2.22 More halogen reacDons

Halogensreactwithhydrogentomakehydrogenhalideswhichwilldissolveinwatertomakeacidicsolu:ons.

Hydrogen+FluorineàHydrogenFluorideH2(g)+F2(g)à2HF(g)

Hydrogen+ChlorineàHydrogenChloride

H2(g)+Cl2(g)à2HCl(g)

Salt

Sodiumfluoride

Sodiumchloride

Sodiumbromide

Sodiumiodide

Halogen

Fluorine Reac:on Reac:on Reac:on

Chlorine Noreac:on

Reac:on Reac:on

Bromine Noreac:on

Noreac:on

Reac:on

Iodine Noreac:on

Noreac:on

Noreac:on

Displacementreac:onscanbeusedtoworkoutthe

rela:vereac:vityofhalogens.

C2.23 Noble gases

Noblegasesarechemicallyinert(unreac:ve)becausetheyhaveafulloutershellofelectrons.

DiscoveryofNobleGases1.  Chemistsno:cedthe

densityofnitrogenmadeinareac:onwasdifferentfromthatofnitrogenintheair.

2.  Chemistsmadeahypothesisaboutthecomposi:onoftheair.

3.  ChemistsperformedteststoshowthepresenceoftheNoblegasesintheair.

UsesofNobleGases Reason

XenonandArgoninsidefilamentlamps

Tostopthehotfilamentreac:ngwithoxygenandburningaway

ArgonandHeliumusedinwelding

Toformablanketoverthehotmetaltostopitreac:ngwithoxygenintheair

Argonusedinfireex:nguishingsystems

Itisnonflammableandcanbeusedtofillacomputerserverroom(forexample)ifafirebreaksout.

Heliumusedtofillballoonsandairships

Ithaslowdensity

Neoninfluorescentlamps Producesaredlightwhenelectriccurrentispassedthroughitunderlowpressure

C2 Topic5ChemicalReac:ons

C2.24 and C2.25 Temperature changes

Keywords

•  Endothermic–reac:onthattakesheatenergyin,decreasingthetemperatureofthereac:onmixtureanditssurroundings

•  Exothermic–reac:onthatreleasesheatenergy,increasingthetemperatureofthereac:onmixtureanditssurroundings

Facts:•  Duringachemicalreac:onthereisusuallya

transferofenergybetweenthereactantandthesurroundings.

Endothermic•  Notmanyreac:onsareendothermic•  E.g.Sodiumhydrogencarbonate+Hydrochloricacid SodiumChloride+Water+Carbondioxide•  Otherendothermicreac:onsinclude:

–  Photosynthesis–  Dissolvingammoniumnitrate

•  TakesinheatenergyExothermic•  Givesoutheat•  Mostreac:onsareexothermic•  Temperatureincrease•  Allcombus:onreac:onsareexothermic•  E.g.Methane+Oxygen•  Explosions–releasealotofheatandgasesveryquickly

Making/breakingbonds•  Energyneededtobreakbond•  Energyreleasedwhenbondsmade

C2.26, 2.27 and 2.28 Rates of ReacDons and Collision Theory

Keywords

•  Rateofreac0on–Thespeedatwhichareac:ontakesplace•  Concentra0on–Ameasureofhowmuchsoluteisdissolvedin

afixedvolumeofsolvent.

•  Surfacearea–Thetotalareaofallthesurfacesofanobjectorsubstance

Factorsaffec0ngRate1.   Concentra0on

•  Moreconcentrated=morepar:cles

•  Morepar:cles=morecollisions=fasterreac:on

2.Temperature•  Highertemperature=fasterreac:one.g.Andeggcooksfasterinboilingwaterthanwarmwater•  Par:cleshavemoreenergy=movefaster

–  Moreeffec:vecollisions(collidewithmoreenergy)–  Collidemorefrequently

3.Surfacearea(SA)

•  Solidbrokenupintosmallerpieces=largerSA•  Greatersurfacearea=fasterreac:on•  Moresurfacearea=morepar:clesonthesurface

thereforemorefrequentcollisions•  A=SmallerSA(block)•  B=LargerSA(powder)

Examples

•  Fastreac:ons=Burning,explosions

•  Slowreac:on=Rus:ng,applebrowning

Catalysts

•  Manychemicalprocessesusecatalyststoincreaserateofproduc:onofproducts

•  Catalystshelptolowerthetemperatureandpressureneeded=lessenergyneeded=savesmoney

Keywords•  Catalyst–Asubstancethatspeedsuptherateofareac:onwithoutbeingused

upinthereac:on•  Cataly0cconverter–DevicefiGedtocarexhaustswithathinlayeroftransi:on

metalcatalystonahoneycombstructuregivingalargesurfacearea..Thecatalystspeedsupthereac:ontocombineCarbonmonoxideandunburnedpetrolintocarbondioxideandwater.

C2.29 Catalysts

Cataly0cconverters•  Reducepollutantsinexhaustgases•  CombineCarbonmonoxide(CO)withoxygen•  Carbondioxideandwaterreleasedinstead•  Containtransi:onmetals(pla:num,rhodiumorpalladium)•  Expensivemetalssosmallamountsused•  Catalystspreadoverahoneycombstructure=largeSurfaceArea•  Worksfasterwiththehotgasesfromtheengineheatitup

B2 Topic6Quan:ta:veChemistry

C2.30 and 2.31 RelaDve Mass

RAM

•  Comparesmasstothatofcarbon12

•  E.g.Hydrogenis12Xlighterthatcarbon

RFM

•  Sumofallmassesintheformula

•  E.g.

EF

•  Simplestwholenumberra:oofatoms/ions

•  E.g.H2Otherearedoublethenumberofhydrogenstooxygen

Keywords•  Rela0veAtomicmass(RAM)–The

meanmassofanatomrela:vetothemassofanatomofcarbon-12,whichhasamassof12.

•  Empiricalformula(EF)–Thesimplestwholenumberra:onofatomsofeachelementinacompound

•  Molecularformula(MF)-Theactualofatomsofeachelementthatcombinetomakeamoleculeofacompound.

•  Rela0veformulamass(RFM)–Thesumoftherela:veatomicmassesofalltheatomsinaformula

B2.32 Percentage composiDon

•  Noatomsarelostormadeinachemicalreac:on.

•  Theyarerearrangedintonewsubstances

•  Youcanuserela:vemassandbalancedequa:onstocalculatethemassofareactantorproduct.

Percentagebymassofanelementinacompound

AM

100

Numberofatomsofelement

= X X

C2.33 Yields

Productsneedtobemakeascheaplyaspossible.Chemistsneedtomakesurethereac:oncreatesasmuchproductaspossible.

Theore0calYield1.  Maximumcalculatedamountofaproductthatcouldbeformedfromagivenamountofreactants.

2. Canbecalculatedfromthebalancedequa:on3. Assumesallreactantareturnedintoproductsandallproductsharvested

ActualYield1. Theactualamountofproductobtainedfromachemicalreac:on.

PercentageYield

1. Theactualyielddividedbythetheore:calyieldasapercentage

Yieldusuallylessthanexpected–3reasons:1.  Reac:onmaybeincomplete

2.  Someproductislost

3.  Otherunwantedreac0onsmayoccurmakingadifferentproduct.

KeywordsYield–theamountofusefulproductobtainedfromareac:on.

C2.34 Waste and Profit

CostEffec0veProcess•  Allfactoriesmustconsiderenvironmentalimpactsincludingdisposalofwaste.

•  Companieswantthemostprofit•  Reac:onsneedtobe

•  Highinpercentageyield•  Allproductsareusefulsotherearenowasteproducts(orusesfoundforwasteproducts–econimicallyviable)

•  Reac:onsarefast(quicktomakelotsofproduct)

Disposal of Waste Products •  Industry make many useful substances (cement, pesDcides, plasDcs) •  Many of the reacDons make waste products: Ø  Not useful Ø  Must be disposed of following strict laws Ø  Expensive to dispose Ø  Can cause environmental problems Ø  Can cause social problems (house prices drop or unpleasant smells)

Keywords•  By-products–Anyproductformedinareac:onin

addi:ontotherequiredproduct•  Wasteproducts–By-productsthathavenouses