chemical reactions - to show that there are two oxygen atoms for ... •malleablebecause atoms...

ChemicalReactionsUnit4

Lesson1:ChemicalBondsUnit4:Reactions

Compounds

• MostsubstancesaroundyouareNOT elements.• Therearearound100elements,butmillionsofdifferentsubstances.• Mostsubstancesarecompounds.Remember,acompoundisasubstancemadeofatomsoftwoormoredifferentelements.• Theatomsofdifferentelementsareheldtogetherincompoundsbychemicalbonds.• Chemicalbondscanhold atomstogetherinlargenetworksorsmallgroups.• Chemicalbondshelpdeterminetheproperties ofacompound.

PropertiesofCompounds

• Thepropertiesofacompounddependon:• Whichelements thecompoundcontains• Howtheatomsarearranged

• Forexample:theatomsofcarbonandhydrogencanformmanythousandsofdifferentcompounds.Eachcompoundhasacertainnumberofcarbonandhydrogenatomsarrangedinaspecificway.Someofthesecompoundsinclude:• Naturalgas• Partsofautomobilegasoline• Hardwaxofcandles• Manyplastics

PropertiesofCompounds

•Thepropertiesofacompoundareverydifferent fromthepropertiesoftheelementsthatmakethem.• Example:Waterismadefromtwoatomsofhydrogenbondedtooneatomofoxygen.Atroomtemperature,hydrogenandoxygenarebothcolorless,odorlessgases.Theyremaingasesdowntoextremelylowtemperatures.However,waterisaliquidattemperaturesupto100˚Candasolidbelow0˚C.

ChemicalFormulas

• Rememberthatatomsofelementscanberepresentedbytheirchemicalsymbols.Achemicalformula usesthesechemicalsymbolstorepresenttheatomsoftheelementsandtheirratiosinachemicalcompound.• Carbondioxideisacompoundconsistingofoneatomofcarbonattachedbychemicalbondstotwoatomsofoxygen.Hereishowyouwouldwritethechemicalformulaforcarbondioxide:• Findthesymbolsforcarbonandoxygenontheperiodictable.Writethesesymbolssidebyside.• Toshowthattherearetwooxygenatomsforeverycarbonatom,placethesubscript“2”totherightoftheoxygenatom’ssymbol.

• Becausethereisonlyoneatomofcarbonincarbondioxide,youdon’tneedasubscriptforcarbon.Thesubscript“1”isneverused.

CarbonDioxide

CO2•Thechemicalformulashowsonecarbonatomsbondedtotwooxygenatoms.

Glucose(Sugar)

SameElements,DifferentCompounds

Vs.

ChemicalBonds

• Chemicalbondsarethe“glue”thatholdstheatomsofelementstogetherincompounds.Chemicalbondsarewhatmakecompoundsmorethanjustmixtures ofatoms.• Chemicalbondsformwhentheelectrons intheelectronshellaroundtwoatomsinteract.Howtheelectronsinteract determinesthekindofchemicalbondthatisformed.• Chemicalbondshaveagreateffecton:• Chemicalandphysicalproperties ofcompounds• Howdifferentsubstancesinteract

TransferofElectrons

• Rememberanion isformedwhenanatomgainsorlosesoneormoreelectrons.• Gaininganelectron=negativeion• Losinganelectron=positiveion

• Ionstypicallyforminpairs whenoneatomtransfersoneormoreelectronstoanotheratom.• Group1metalscommonlyloseoneelectrontoformpositive ions.(1+)• Group2metalscommonlylosetwoelectronstoformpositive ions.(2+)• Transitionmetalsalsolose(variousamountsof)electronstoformpositive ions.• Group17nonmetalscommonlygainoneelectrontoformnegative ions.(1-)• Group16nonmetalscommonlygaintwoelectronstoformnegative ions.(2-)

IonicBonds

• Ingeneral,ionicbondsformbetweenmetals andnonmetals.Themetalloses theelectron(s),sothenonmetalgains theelectron(s).•WhenanatomofanelementfromGroup1comesnearanatomofanelementfromGroup17,theyformanionicbond.Anionicbondistheforceofattractionbetweenpositiveandnegativeions.• Ionicbondsformbetweenallnearbyionsofoppositecharge.• Thesebondsmakeioniccompoundsverystableandstrong.

NamesofIonicCompounds

• Thenameofanioniccompoundisbasedonthenamesoftheionsitismadeof.• Thenameofapositiveionisthesameasthenameoftheatomsfromwhichitisformed.• Thenameofanegativeionisformedbydroppingthelastpartofthenameoftheatomandaddingthesuffix-ide.

• Tonameanioniccompound,thenameofthepositiveionisplacedfirst,followedbythenameofthenegativeion.• Example:SodiumChloride• Sodiumisthepositiveion;chlorineisthenegativeion

CovalentBonds

•Anotherwayinwhichatomscanbondtogetherisbesharingelectrons.Nonmetal atomsusuallyformbondswitheachotherinthisway.•Apairofsharedelectronsbetweentwoatomsiscalledacovalentbond.• Informingacovalentbond,neitheratomgainsorlosesanelectron,sono ionsareformed.

CovalentBonds

• Thesharedelectronsareattractedtoboth positivelychargednuclei.• Thenumberofcovalentbondsthatanatomcanformdependsonthenumberofelectrons thatithasavailableforsharing.• Example:AtomsoftheHalogenfamily(Group17)cancontributeonlyone electrontoacovalentbond.• Example:Group16=2covalentbonds;Group15=3 covalentbonds;Carbon&Silicon=4 covalentbonds

CovalentBonds

Agroupofatomsheldtogetherbycovalentbondsiscalledamolecule.

CovalentBonds

• Sometimesatomsmaysharemorethanonepairofelectronswithanotheratom.Adoublebondconsistsoffour(twopairsof)sharedelectrons.

• Atriplebondmeansthattheatomssharesix(threepairsof)electrons.

CovalentBonds

MetallicBonds

•Metal atomsbondtogetherbysharingtheirelectronswithoneanother.• Theatomssharetheelectronsequally inalldirections,whichallowstheelectronstomoveeasilyamongtheatomsofthemetal.• Thepropertiesofmetalsaredeterminedbymetallicbonds.• Good conductorsbecauseofthefreemovementofelectrons•Malleable becauseatomscanslidepastoneanother

Checkpoint:ChemicalBonds

1.Whatisthedifferencebetweenanionicbondandacovalentbond?

Ionicbond:Oneatomlosesanelectron,whiletheotheratomgainstheelectron.Covalentbond:Electronsaresharedbetweentwoatoms.Neitheratomgainsorlosesanelectron.

Lesson2:ChemicalReactionsUnit4:Reactions

ChemicalReactions

•Rememberthatachemicalchangeoccurswhensubstanceschangeintooneormoredifferent(new)substances.•Achemicalreactionproducesnewsubstancesbychangingthewayinwhichatomsarearranged.• Inachemicalreaction,bondsbetweenatomsarebrokenandnewbondsformbetweendifferentatoms.• Thisbreakingandformingofbondstakesplacewhenparticlesoftheoriginalmaterialscollidewithoneanother.Afterachemicalreaction,thenewarrangementsofatomsformdifferentsubstances.

ReactantsandProducts

•Reactants arethesubstancespresentatthebeginningofachemicalreaction.• Example:Intheburningofnaturalgas,methane(CH4)andoxygen(O2)arethereactants.CH4 +O2à CO2 +H2O

•Products arethesubstancesformedbyachemicalreaction.• Example:Intheburningofnaturalgas,carbondioxide(CO2)andwater(H2O)aretheproducts.CH4 +O2à CO2 +H2O

•Reactantsandproductscanbeelementsorcompounds,dependingonthereactiontakingplace.

ReactantsandProducts

•Duringachemicalreaction,bondsbetweenatomsinthereactantsarebroken andnew bondsareformedintheproducts.• Example:Whennaturalgasisburned,bondsbetweenthecarbonandhydrogenatomsinmethanearebroken.Bondsbetweentheoxygenatomsintheoxygenmoleculesarebroken.Newbondsareformedbetweencarbonandoxygenincarbondioxidegasandbetweenhydrogenandoxygeninwatervapor.

EvidenceofChemicalReactions

• Somechemicalchangesareeasytoobserve.Othersarenotaseasytosee.Ifyouobservetwoormoreofthesesignsduringachange,youmostlikelyareobservingachemicalchange:• Productionofanodor• Changeintemperature• Changeincolor• Formationofagas(bubbles)• Formationofaprecipitate (asolid)

ClassificationofChemicalReactions

•Chemicalreactionscanbeclassifiedbasedonthewaystheproductsaremade:•Synthesis•Decomposition•Combustion

ClassificationofChemicalReactions:Synthesis

•Inasynthesis reaction,anewcompoundisformedbythecombination ofsimplerreactants.•Example:nitrogendioxide(NO2),apartofsmog,formswhennitrogenandoxygencombineintheair.

ClassificationofChemicalReactions:Decomposition

• Inadecomposition reaction,areactantbreaksdownintosimplerproducts.Theproductscouldbeelementsorothercompounds.Decompositioncanbethoughtofasbeingthereverseofsynthesis.• Example:watercanbedecomposedintoitselements–hydrogenandoxygen.

ClassificationofChemicalReactions:Combustion

• Inacombustion reaction,onereactantisalwaysoxygen.Anotherreactantoftencontainscarbonandhydrogen.Thecarbonandhydrogenatomscombinewithoxygen,producingcarbondioxideandwater.• Example:Theburningofmethaneisacombustionreaction.

TheRatesofChemicalReactions

•Mostchemicalreactionstakeplacewhenparticlesofreactantscollide withenoughforcetoreact.•Chemicalreactionscanoccuratdifferent rates.• Strikingamatchcauseaveryquickchemicalreaction.• Therustingofanironnailmaytakemonths.


•However,thefollowingfactorscanchangetheratesofchemicalreactions:• Concentration – Thenumberofparticlespresentinacertainvolume.Ahigh concentrationofreactantsmeansalargenumberofparticlesthatcancollideandreact.• Example:Turningupthegasstoveincreasestheconcentrationofmethanemoleculesthatcancombinewithoxygenintheair.Theresultisabiggerflamesandafastercombustionreaction.


•However,thefollowingfactorscanchangetheratesofchemicalreactions:• Surfacearea – Supposeoneofthereactantsinachemicalreactionisasinglelargepieceofmaterial.Particlesofthesecondreactantcannotgetinsidethelargepiece.Theycanreactonlywithparticlesonthesurface.• Tomakethereactiongofaster,thelargepieceofmaterialcouldbebrokenintosmallerpiecesbeforethereactionstarts.Breakingitintosmallerpiecesincreasethesurfaceareaofthematerial,whichincreases therateofthereaction.


•However,thefollowingfactorscanchangetheratesofchemicalreactions:• Temperature – Therateofareactioncanbeincreasedbymakingtheparticlesmovefaster.Theresultisthatmorecollisionstakeplacepersecondandoccurwithgreaterforce.Thewaytomaketheparticlesmovefasteristoaddenergytothereactants.Addingenergyraisestheirtemperature.• Example:Manychemicalreactionsincookingdonotoccurunlessheatisadded.Usuallythereactionsincookingcanbestoppedbyremovingthefoodfromtheheatsource.


•However,thefollowingfactorscanchangetheratesofchemicalreactions:• Catalysts:Therateofareactioncanbechangedchemicallybyaddingacatalyst.Acatalyst isasubstancethatincreasestherateofachemicalreactionbutisnotitselfconsumedinthereaction.Thismeansthatafterthereactioniscomplete,thecatalystremainsunchanged.• Catalystsareveryimportantformanyindustrialandbiologicalreactions.Infact,manychemicalreactionswouldproceedslowlyornotatallwithoutcatalysts.

Energy

•TheLawofConservationofEnergystatesthatenergycannotbecreatedordestroyed.Itcanonlybetransferredtoadifferenttypeofenergy.•Energyisneededtobreakbondsinreactantmolecules.•Energyisreleasedwhenbondsareformedinproductmolecules.

ExothermicChemicalReactions

•Sometimesmoreenergyisreleasedwhenproductsformthanisneededtobreakthebondsinthereactants.Thenenergyisreleasedduringthereaction.•Areactioninwhichenergyisreleasediscalledanexothermicreaction.•Thisenergyisoftenreleasedasheat.• Example:Allcommoncombustionreactions

EndothermicChemicalReactions

• Sometimesmoreenergyisrequiredtobreakthebondsinthereactantsthanisreleasedwhentheproductsform.Thenenergymustbeaddedtothereaction.Thatis,thereactionabsorbsenergy.•Areactioninwhichenergyisabsorbediscalledanendothermicreaction.• Endothermicreactionsoftenproduceadecrease intemperature.

Photosynthesis

•ProbablythemostimportantseriesofendothermicreactionsonEarthisphotosynthesis.•Photosynthesisistheendothermicprocessbywhichlightisabsorbedandusedtochangecarbondioxideandwaterintooxygenandglucose.•Unlikemanyotherendothermicreactions,photosynthesisdoesnot absorbenergyasheat.• Theenergyisstoredintheglucosemolecules,readytobeusedbytheplantswhenneeded.

Photosynthesis

LawofConservationofMass

•TheLawofConservationofMassstatesthatinachemicalreaction,atomsareneithercreatednordestroyed.• FrenchchemistAntoineLavoiseir concludedthislawthroughworkinthe1780s.• Inotherwords:Allatomspresentinthereactantarealsopresentintheproducts.

LawofConservationofMass

•Thetotalmassofreactantsisequal tothetotalmassofproducts.• Example:Themassofsodiumplusthemassofchlorinethatreactswiththesodiumisequaltothemassoftheproductsodiumchloride.Becauseatomsareonlyrearrangedinachemicalreaction,theremustbethesamenumberofsodiumatomsandchlorineatomsintheboththereactantsandproducts.

ChemicalEquations

•Achemicalequationrepresentshowatomsarerearrangedinachemicalreaction.• Theatomsinthereactantsareshownontheleft sideoftheequation.• Theatomsintheproductsareshownontheright sideoftheequation.•Noatomsarecreatedordestroyed.Thenumberofatomsofeachdifferentelement,therefore,mustbethesameoneachsideoftheequation.

ChemicalEquations

• Inordertowriteachemicalequation,youneedtoknow:• Thereactantsandproductsinthereaction• Theatomicsymbolsandchemicalformulasofthereactantsandproductsinthereaction• Thedirectionofthereaction

C+O2 à CO2

“Carbonreactswithoxygentoyieldcarbondioxide.”

ChemicalEquations

•ChemicalreactionsfollowtheLawofConservationofMass.Theequationsshowthisequalityintermsofatoms.•Thesamenumberofatoms ofeachelementmustappearonboth sidesofachemicalequation.•Youmustbalance theequationtomakethenumberofatomsequaloneachsideoftheequation.

BalancingChemicalEquations

•Thenumbersinfrontofthechemicalformulasarecalledcoefficients.•Coefficients indicatehowmanymoleculestakepartinthereaction.Ifthereisnocoefficient,thenonlyonemoleculeofthattypetakespartinthereaction.•Rememberasubscript indicatesthenumberofatomsofanelementinamolecule.

CoefficientsVs.Subscripts

3NaCl

Coefficient

3molecules ofNaCl =NaCl NaCl NaCl

H2O

Subscript

2atoms ofhydrogenin1moleculeofH2O=HHO

3H2O3molecules ofH2O(with2atomsofhydrogenineach molecule)

=H2OH2OH2O

=HHOHHOHHO

=6atomsofH3atomsofO

BalancingChemicalEquations

CH4 +O2 à CO2 +H2O

H4=4atomsofhydrogen

Need4atomsofhydrogen

2

Nowwehave4atomsofoxygen

Weneed4atomsofoxygen

2

C=1H=4O=4

C=1H=4O=4

Lesson3:SolutionsUnit4:Reactions

Solutions

• Asolution isamixtureoftwoormoresubstancesthatisidenticalthroughout.• Ifyoustirsandintoaglassofwater,youcanidentifythesandasaseparatesubstancethatfallstothebottomoftheglass.Sandinwaterisamixture,butnotasolution.• Ifyoustirsugarintoaglassofwater,youcannotidentifythesugarasaseparatesubstance.Therefore,sugarinwaterisacommonsolution.•Manysolutionshavecertainproperties thatmakeuscallthemacidsorbases.

Acids

•Acidsarefoundinmanyfoods,suchasorangejuice,tomatoes,andvinegar.•Theytasteslightlysour whendissolvedinwaterandproduceaburningoritchy feelingontheskin.•Strongacidsshouldnever betastedortouched.Thesesolutionsareusedinmanufacturingandaredangerouschemicals.

Bases

•Basesarethechemicalopposite ofacids.•Theytendtotastebitter,ratherthansour,andoftenfeelslippery tothetouch.•Basesarealsofoundincommonproductsaroundthehome,includingsoap,ammonia,andantacids.•Strongbases,likethelyeusedforuncloggingdrains,arealsodangerous chemicals.

Acids,Bases,andIons

•Generally,acompoundthatisanacidorabaseactsasanacidorabaseonlywhenitisdissolved inwater.• Inawater-basedsolution,thesecompoundsproduceions.•Forexample,ifahydrogenatom,whichconsistsof1protonand1electron,losesitselectron,itbecomesahydrogen ion.Ithasapositive charge.

Acids

•Anacid isasubstancethatcandonateahydrogenion(aproton)toanothersubstance.• Forexample,whenthecompoundHCl isdissolvedinwater,thecompoundseparatesintohydrogenions(H+)andchlorideions(Cl-).Thehydrogen ionsarefreetoreact withothersubstances,sothesolutioniscalledanacid.•Whenhydrogenchlorideisdissolvedinwater,thesolutioniscalledhydrochloricacid. H2Ol l

Bases

•Abase isasubstancethatcanacceptahydrogenionfromanothersubstance.• Forexample,whenthecompoundNaOH isdissolvedinwater,thecompoundseparatesintosodiumions(Na+)andhydroxideions(OH-).Thehydroxideionsarefreetoacceptprotonsfromeithersubstances,sothesolutionisabase.• ThesolutionthatresultswhenNaOH isdissolvedinwateriscalledsodiumhydroxide. H2O

AtomicLevel

•Onanatomiclevel,thedifferencebetweenacidsandbasesisthatacidsdonate protonsandbasesaccept protons.•Whenaproton– ahydrogenion– fromanacidisacceptedbyahydroxideionfromabase,thetwoionsjointogetherandformamoleculeofwater.• Thissimpletransferofprotonsbetweensubstancesisinvolvedinmanyusefulandimportantchemicalreactions.

TestingforAcids

• Onesafewaytotestforanacidistoplaceafewdropsofasolutiononacompoundthatcontainsacarbonate (CO3).• Forexample,limestone isarockthatcontainscalciumcarbonate(CaCO3).Whenanacidtouchesapieceoflimestone,areactionoccursthatproducescarbondioxidegas.

• Acidsalsoreactwithmostmetals.Thereactionproduceshydrogengas,whichyoucanseeasbubbles.• Themostcommonwaytoidentifyistheirabilitytochangecolorsofcertaincompoundsknownasacid-baseindicators.Onecommonindicatorislitmus,whichisoftenpreparedonslipsofpaper.Whenadropofacidisplacedonlitmuspaper,thepaperturnsred.

TestingforBases

•Basesfeelsoapyorslipperybecausetheyreactacidicmoleculesinyourskincalledfattyacids.Thisisactuallyhowsoapismade– mixingabase(usuallysodiumhydroxide)withfattyacidsproducessoap.So,whenabasetouchesyourskin,thecombinationofthebasewithyourownfattyacidsactuallymakesasmallamountofsoap.•Basesalsochangethecolorsofacid-baseindicators.Whenadropofbaseisplacedonlitmuspaper,thepaperturnsblue.

StrengthsofAcids

• Strong acidsbreakapartcompletelyintoions.• Example:Hydrogenchloride(HCl)dissolvesinwatertoformhydrochloricacid.Itbreaksdownintohydrogenionsandchlorideions.Nohydrogenchlorideremainsinthesolution.Becauseallthehydrogenchlorideformsseparateions,hydrochloricacidisastrongacid.

•Weak acidsdonotformmanyionsinasolution.• Example:Aceticacid(HC2H3O2)istheacidinvinegar.Whenitdissolvesinwater,onlyabout1%oftheaceticacidbreaksupintohydrogenionsandacetateions.Theother99%oftheaceticacidremainsunchanged.Therefore,itisaweakacid.

StrengthsofBases

•Basescanalsobestrongorweak.Whensodiumhydroxide(NaOH)dissolvesinwater,itformssodiumions(Na+)andhydroxideions(OH-).NoneoftheoriginalNaOH remainsinthesolution,sosodiumhydroxideisastrong base.•Whenammonia(NH3)dissolvesinwater,onlyabout1%oftheammoniareactswithwatertoformOH- ions.Theother99%remainsunchanged.Therefore,ammonia isaweak base.

MeasuringAcidity

• Theacidityofasolutiondependsontheconcentration ofH+ionsinthesolution.ThisconcentrationisoftenmeasuredonthepHscale.•ApHscalerepresentsahighH+ concentrationwithalownumber(acid)andalowH+ concentrationwithahighnumber(base).•Aneutralcompoundisasubstancethatisneitheranacidorabase.

MeasuringAcidity

•ApHscaleusuallyhasarangefrom0-14.•Numbersbelow 7indicateacidic solutions.AconcentratedstrongacidhasalowpHvalue.•Numbersabove 7indicatebasic solutions.AconcentratedstrongbasehasahighpHvalue.•Neutral compounds– likepurewater– haveapHof7.

pHScale

Checkpoint:Solutions

1. ExplainhowtoreadapHscale.

0-6=acidicsolution(highH+ concentration)7=neutral8-14=basicsolution(lowH+ concentration)

Lesson4:ChemistryofLivingThings

Unit4:Reactions

ChemistryofLivingThings

•Chemicalreactionshappeneverywhere,includinginlivingthings.• Example:Exothermicreactionsprovideuswiththeenergyweneedforournervestoworkandacidstobreakdownfoodinourstomachs.

•Biochemistry isthestudyofthesubstancesandprocessesoccurringinlivingorganisms.

CompositionofLivingThings

•Closeto100elementsoccurnaturally.Ofthese,25arefoundinlivingthings.•Thesixmostcommonelementsinlivingthingsare:• Carbon• Hydrogen• Oxygen• Nitrogen• Phosphorus• Sulfur

OtherElements

• Otherelementsarealsoimportanttotheproperfunctioningoforganisms.Theseelementsinclude:• Sodium&potassiumions– keyroleinthetransmissionofnerveimpulsesbetweenyourbrainandallpartsofthebody• Calciumions– essentialformusclecontractionsandtheclottingofblood• Fluorine– formsasaltwithcalcium,whichmakesteethstronger• Iron– helpscarryoxygeninthebloodtobodycells• Chlorine– combineswithhydrogentocreateacidinthestomachtobreakdownfood• Magnesium– musclecontractions

WaterandSalt

•Thehumanbodyreliesonmanycompounds.Manyofthesehaveverycomplicatedmolecularstructures.•However,twoofthemostimportant compounds,waterandsalt,haveverysimplechemicalstructures.Theyareimportantbecauseofthetypesofbondstheycontain.

Water

•Rememberthatwaterisacovalent bond.Thesebondsmakewateranexcellentsolvent.Ourbodycellscontainmostlywater,somanysubstancescandissolve insidecells.•Thisallowsmanychemicalreactions totakeplaceaswell.Substances(includingblood)caneasilypassinsolutionfromtheoutsideofthecelltotheinsideofthecell.

Salt

• Salt(NaCl)isanotherusefulcompoundforthebody.Rememberthatsaltisanionic bond.Whenioniccompoundsdissolveinwater,theyseparateintopositiveandnegativeions.Theseionsareinsolutioninthebloodandcells.• SaltseparatesintoNa+ andCl- ions.Separatedionsallowasolutiontoconductelectriccurrent.Thisishowthebodysendsnerveimpulses.• Sodiumionsalsohelptokeeptheamountofwaterconstantinthecellsofbodytissues.Theyregulatetheamountofwaterthatpassesinandoutofthecells.• Chlorideionscombinewithhydrogentomakehydrochloricacid,whichhelpsourbodydigestfood.

Carbon

• Althoughcarbon isnotthemostabundantelementinlivingthings,itisthemostimportant.Carbonhastheabilitytobondwithotheratomsindifferentways.• Organiccompoundsarecompoundsbasedoncarbon.Alllivingthings(organisms)areorganicbecausetheycontaincarbon.• However,notallsubstancesmadefromcarbonarefoundinlivingthings.• Examples:diamonds,graphite– entirelymadeofcarbon,butnotorganic

• Acompoundthatisnotconsideredorganiciscalledaninorganiccompound.Thisincludesallcompoundsthatdonotcontaincarbon.Butitalsoincludessomecarbon-containingcompoundsthatarenotfoundinlivingthings.

Carbon

•Millions ofdifferentcarbon-basedmoleculesexist.•Carbon-basedmoleculescanhavemanydifferentstructures.• Oneimportantstructurehasmoleculesshapedlikelongchains.• Anotherstructurehasmoleculesshapedlikerings.

CarbonChains

• Unlikeatomsofotherelements,carbonatomscanbondtoeachothertoformverylongchains.Onecarbonchainmightcontainhundredsofcarbonatoms.Acarbonchaincanbestraightorbranched.• Inabranchedcarbonchain,othercarbonatoms,orevenothercarbonchains,canbondtocarbonatomsinthemaincarbonchain.• Straightchainsandbranchedchainsarebothresultsofcarbon’sabilitytoformfour bonds.Averylargecarbon-basedmoleculemadeofrepeatingunitsiscalledapolymer.• Eachunitofapolymerisknownasamonomer.• Apolymercanbethousandsofatomslong.

Isomers

• There’sanotherreasonwhytherearesomanycarbon-basedmolecules.•Carboncanformdifferent moleculeswiththesame atoms.Theatomsinthesemoleculesareindifferentplaces,thereforetheyhavedifferentstructures.•Becausetheatomsarearrangeddifferently,theyareactuallytwodifferentsubstances.Compoundsthatcontainthesameatoms,butindifferentplaces,arecalledisomers.

BuildingBlocksofLife

• Theorganicmoleculesinlivingthingsfallintofourmajorgroups:carbohydrates,lipids,proteins,andnucleicacids.• Carbohydrates includesugarsandstarches.Theyarefoundingoods,likepastaandbread.• Lipids arefatsoroils.• Proteins arenecessaryformanyfunctionsinthebody,includingtheformationofmuscletissue.•Nucleicacids arethemoleculesthatcarrythegeneticcodeforalllivingthings.

Carbohydrates

•Carbohydrates areatypeofmoleculemadeupofsubunitsofsugars,andareusedforenergyandstructure.• Theyincludesugars,starches,andcellulose.• Theycontainthreeelements:carbon,hydrogen,andoxygen.• Twomainfunctions:• Sourceofchemicalenergy forcellsinmanylivingthings•Partofthestructural materialsofplants

Lipids

• Lipidsareatypeofmoleculemadeupofsubunitsoffattyacids.Lipidsarefoundinfats,oils,andwaxes,andareusedforstructureandtostoreenergy.•Mostlipidsaremadeofcarbon,hydrogen,andoxygen.•Animalsstorechemicalenergyinfat;plantsstorechemicalenergyinoils.• Somelipidsareimportantpartsofcellstructure.

Proteins

• Proteinsareoneofthemanytypesofmoleculesmadeupofchainsofaminoacidsubunits.Theycontrolthechemicalactivityofacellandsupportgrowthandrepair.• Proteinscontaincarbon,hydrogen,oxygen,nitrogen,sulfur,andotherelements.• Thereareatleast100,000 proteinsinyourbody,eachwithadifferentstructurethatgivesitaspecificfunction:• Structuralmaterials• Controlchemicalreactions• Transportsubstanceswithincells• Partoftheimmunesystemandprotectyoufrominfections

Enzymes

•Someproteinsthatcurlupintoashapeofaballareenzymes.Enzymes areacatalystforachemicalreactioninlivingthings.•Theyarenecessaryformanychemicalreactionsinyourbody.Withoutenzymes,thesereactionswouldoccurtooslowly tokeepyoualive.

NucleicAcids

•NucleicAcidsareatypeofmoleculethatispartofthegeneticmaterialofacell,andisneededtomakeproteins.• Examples:DNAandRNA

• Theyaremadeofcarbon,hydrogen,oxygen,nitrogen,andphosphorus.• Eachofthecells inyourbodycontainsacompletesetofnucleicacids.Thismeansthateachcellhasalltheinstructionsnecessaryformakinganyproteininyourbody.

chemical reactions - to show that there are two oxygen atoms for ... •malleablebecause atoms...

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