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The Free High School Science Texts: A Textbook for High ...

TheFreeHighSchool ScienceTexts:A TextbookforHighSchool Students , 20051 2003\FreeHighSchool ScienceTexts"Permissionis grantedto copy, distributeand/ormodifythisdocu-ment underthetermsof theGNUFreeDocumentationLicense, any laterversionpublishedby theFreeSoftwareFoun-dation;withnoInvaria nt Sections,noFront-Cover Texts,andnoBack-Cover copy of thelicenseis includedin thesectionentitled\GNUFreeDocumentationL icense".iContentsIMATTERANDMATERIALS11 Classi cationof Materials(Grade10)22 Whatis mattermadeof? (Grade10)33 TheAtom(Grade10) theatom.. Model/ QuantumMechanicalModel.. guration.. of ionizationenergyto supportatomarrangement inPeriodicTable.. ionisationenergiestoprovideevidenceforar range-ment of electronsinto coreandvalence..94 Atomiccombinations,Molecularstructure,Ch emicalBonding(Grade11).

12 Energy and Chemical Change (Grade 11) 77 13 Reaction Types (Grade 11) 78 ... Chapter 1 Classiflcation of Materials (Grade 10) Observing, describing, Classifying and using materials (a macroscopic view) †The material(s) of which an object is composed †Mixtures { Heterogeneous mixtures

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Transcription of The Free High School Science Texts: A Textbook for High ...

1 TheFreeHighSchool ScienceTexts:A TextbookforHighSchool Students , 20051 2003\FreeHighSchool ScienceTexts"Permissionis grantedto copy, distributeand/ormodifythisdocu-ment underthetermsof theGNUFreeDocumentationLicense, any laterversionpublishedby theFreeSoftwareFoun-dation;withnoInvaria nt Sections,noFront-Cover Texts,andnoBack-Cover copy of thelicenseis includedin thesectionentitled\GNUFreeDocumentationL icense".iContentsIMATTERANDMATERIALS11 Classi cationof Materials(Grade10)22 Whatis mattermadeof? (Grade10)33 TheAtom(Grade10) theatom.. Model/ QuantumMechanicalModel.. guration.. of ionizationenergyto supportatomarrangement inPeriodicTable.. ionisationenergiestoprovideevidenceforar range-ment of electronsinto coreandvalence..94 Atomiccombinations,Molecularstructure,Ch emicalBonding(Grade11).

2 A molecule?.. of bonding.. bonding.. molecularstructure..165 Atomicnuclei(Grade11) theatommadeof? .. radioactivity .. , , and rays .. theionizingradiation.. law .. dating.. screen.. 'schamber.. decay .. nature.. theuniverse..476 ThermalProperties& IdealGases(Grade11) 'sLaw : Pressureandvolumeof anenclosedsampleof 'sLaw:Volumeandtemperatureof anenclosedsampleof gas.. 'sHypothesis:Thelinkbetweennumber of gasparticlesandvolume.. GeneralEquations.. theKineticTheoryof Matter..567 OrganicChemistry:Molecules(Grade12) .. organicchemistry?.. carbon.. organiccompounds.. cationof organiccompounds.. OrganicCompounds.. organiccompounds.. organiccompounds.. ,carboxylicacidsandesters..668 OrganicChemistry:Macromolecules(Grade12) 68 IICHEMICALCHANGE699 PhysicalandChemicalChange(Grade10)7010 RepresentingChemicalChange(Grade10).

3 7211 Quantitative Aspectsof ChemicalChange(Grade11)7612 EnergyandChemicalChange(Grade11)7713 ReactionTypes (Grade11) .. of ChemicalReactions.. gases..7914 ReactionRates(Grade12) ectingreactionrates.. chemicalreactions.. ect.. solution.. product..8815 ElectrochemicalReactions(Grade12) .. reagents.. reactions .. electrochemicalcells.. (Leclanchecell).. water.. Aluminium.. ningof copper.. 'slawsof electrolysis.. 102 IIICHEMICALSYSTEMS10716 TheWaterCycle(Grade10)10817 TheNitrogenCycle(Grade10) .. (N2) .. Nitrogen.. (N H3) .. H3.. H3.. H3.. AmmoniumSalts.. AmmoniumSalts.. AmmoniumSalts.. (N O2) .. :.. O2andN2O4.. (HN O3) .. O3: .. O3: .. NitricAcid:.. NitricAcid:.. :.. 11518 TheHydrosphere(Grade10)116v19 TheLithosphere:ExploitingtheEarth'scrust (Grade11)11720 TheAtmosphere(Grade11)11821 TheChemicalIndustry:Resources,Needsandth eChemicalConnection(Grade12)119 Essay1: SyntheticPolymers120A GNUFreeDocumentationLicense123viPartIMAT TERANDMATERIALS1 Chapter1 Classi cationof Materials(Grade10)Observing,describing,C lassifyingandusingmaterials(a macroscopicview) Thematerial(s)of which anobjectis composed Mixtures{Heterogeneousmixtures{Homogeneo usmixtures Puresubstances:elements andcompounds Namesandformulaeof substances Metals,semimetalsandnonmetals Electricalconductors,semiconductorsandin sulators Thermalconductorsandinsulators Magneticandnonmagneticmaterials2 Chapter2 Whatis mattermadeof?}}

4 (Grade10) Atomsandmolecules(simpleandgiant) Materialstructuresandproperities:Linking macroscopicpropertiesofmaterialsto micro(particle)structure Intermolecularandintramolecularforces(ch emicalbonds).Physicalstateanddensity explainedin termsof (NOTETOSELF:(someis coveredalreadybutnotall))3 Chapter3 TheAtom(Grade10) Energyquantizationandelectroncon guration ThePeriodicTableof theElements:Periodicity of ionizationenergytosupportthearrangements of theatomsin thePerodicTableSuccessiveionizationenerg iesto provideevidenceforthearrangement of electronsinto coreandvalenceelectronsAtomsarethebuildi ngblocks of allthestruc-turesandorganismsin ,thesun,grassandtrees,theairwe breathe,andpeopleareallmadeupof di erent combinationsof atomswas inventedby two Greekphilosophers,DemocritusandLeucippus in the o o (atom)meansindi-visiblebeacausetheybelie ved thatatomscouldnotbe broken downinto ,thediscoveryof thefactthatanatomis actuallya complexsystemandcanbe broken into pieceswas themostimportant stepandpivotingpoint in thedevelopment of modernphysics!

5 TheatomNowadays,we know thatatomsaremadeupof apositivelychargednucleusinthecentresurr oundedby orbitingnegativelychargedelectrons. However,inthepast,beforethestructureof theatomhadbeendiscovered,scientistscameu pwithlotsof di erentmodelsorpicturesto describe discovered(by 1897),peoplerealisedthatatomsweremadeupo f even smallerparticlesandtheplumpuddingmodelwa s thispicture,atomsarethought of as thenegative electrons oatingin a soupof positive chargelike plumsin a puddingor raisinsin a fruitcake! ,it was discovered(by Rutherfordin 1911)thatatomshave apositivelychargednucleus(centre)withthe negative wrongandscientiststhenpicturedtheatomlik e a minisolarsystemwheretheelectronsorbitthe nucleuslike exampleit couldnotexplaintheveryinterestingobserva tionthatatomsonlyemitlight at certainwavelengthsor proposingthattheelectronscouldonlyorbitt henucleusin levels.

6 Theexactenergiesof theorbitalsdependsonthetype of atom,forexampleHeliumhasdi erentenergylevelsto anelectronjumpsdownfroma higherenergylevel(ororbital)to a lower energylevel,thenlight is thelight emittedis thesameas thegapin theenergybetweenthetwo energylevels!InterestiingFact:Interestii ngFact:Lighthasthepropertiesof botha particleanda wave!Einsteindis-coveredthatlightcomesin energypacketswhichare anatomchangesenergylevels,a photonof lightis thedi erencebetweenthetwo electronenergylevels!Onceanelectronis in itslowestorbit,it cannotgo downany theHydrogenatom(nucleusplusoneelectron)b y calcu-latingthedistancebetweenthenucleus andtheelectronin knownas nition:TheBohrradius,a0, is theradiusof thelowestenergyelectronorbitin 5:29177210810 Model/ QuantumMechanicalModelThefactthatBohr'se lectronenergylevelscouldonlytake certainenergyvalueswas a hint thatsomenewphysicswas at play in we usewhatis calledquantummechanicsorwavemechanicsto describe thebehaviourofverysmallparticlesat quantummechanics,particlescanbe describedaswavesinsteadof littlebilliardballs.

7 (We discussedearlierthatlight canbe thought of as a wave, or as a particlecalledthephoton.) Thenthepropertiesof theparticle,forexampleitspositionor velocity, aredescribedby :Probabilitiesdescribe thechanceof somethinghappeningorof a valuebetween0 and1 or 0%and100%where0 meansnochanceatalland1 meansde somethingis , a 50%(= )chanceof thequantummechanicalmodelof theatom,youcanimaginetheelectronas a wave. Thentheelectrondoes notmove alonga speci cpathin its orbit,butratheralongallimaginablepathswi thdi erent we weretryingto catch thiselectron,aftermany attemptswe woulddiscover thattheelectroncanbe foundanywerearoundthenucleus,even verycloseto ,theprobabilitiesof ndingtheelectronat di erent distancesfromthenucleuswouldbe di youpicturetheelectronas a cloudaroundthenucleusthenin someplacesthiscloudwillbe denser(thicker)whilein otherplacesit willbe lessdense(thinner).

8 Thedensity of thecloudcorrespondsto theprobability of ndingtheelectronin a particularplace!Quantummechanicsis veryusefulbecauseonecanuseit to calculatetheprobability of ndingtheelectronat any pointin such a calculationforthehydrogenatomareshownin theprobability of ndingtheelectronandonthex-axisis thedistanceaway fromthecenterof (highestpoint onthecurve) is thesameas theBohrradius!P(r) :Probability densityP(r)for ndingtheelectronat a distancerfromtheprotonin thegroundstateof verytiny comparedto thetotalmassof becausemostof themassof theatomis dueto thenucleus!In thesiliconatomsthatarethemaincomponent of therocks aroundus,all14electronsmake heavyrock in yourhand,youactuallyfeelthecollective weight of allthenucleithatareinsideit! ,we have discussedthatatomsaremadeupof anucleussurroundedbyoneor a verylight hasa massof 10 31kg!

9 Currently,scientistsbelieve thattheelectroncanbe treatedas apointparticleorelemen-taryparticlemeani ngthatit cannotbe brokendowninto theelectron,thenucleuscanbe brokenupinto smallerbuildingblocks:protonsandneutrons . 'sRutherfordandotherphysicistsperformedm any experi-ments,changingoneelement into anotherby was apparent thatthehydrogennucleusplayeda fundamentalrolein nuclearstructureandwas a constituent partof 'sphysicistswereregularlyreferringto thehydrogennucleusas was establishedthatatomicnucleiconsistedof protoncarriesapositivechargeof + chargeof a nucleusis equalto thenumber of protonsin thenucleus!Sincewe know thatatomsareelectrically neutral, extracharge,thenthenumber ofprotonsin anatomhasto be thesameas thenumber of electronsto balanceoutthepostive andnegative chargeto zero!

10 TheNeutronHowever,onlyhavingprotonsin thenucleusleadsto exam-ple,if therewereonlypositivelychargedprotonsin thenucleus,thenit shouldbreakinto bitsdueto therepulsive electrostaticforcesbetweentheprotons!An- otherproblemwas thattheprotonsin thenucleuswerenotenoughto accountforthemeasuredmassof di erent atoms!Forexample,if protonsweretheonlyparticlesin thenucleus,thena heliumnucleus(atomicnumber 2) wouldhave two protonsandthereforeonlytwicethemassof ,itis additionto (in1920)thatanotherkindof particlemustbe present in thenucleusalongwiththeprotonto helpholdthenucleustogetherandaddto its ensuretheatomremainselectricallyneutralt hisparticlehadto 1932 JamesChadwick discoveredtheneutronandmeasureditsmass,w hich turnedoutto be almostthesame,butslightlylargerthanthato f an element aredeterminedby thechargeof its atomicnucleus, thenumber of protons.


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