Chapter7:KineticMolecularTheory

7.1StatesofMatter

7.1KMTandChangesinState

Matter:anythingwithmassandvolume

• Mass:quantityofmatterthatasubstanceorobjectcontains(g orkg)

• Volume:amountofspacetakenupbyasubstance(mL,L,orcm3)

Circletheitemsbelowthataremadeupofmatter.

ThreeStatesofMatter

Solid – definitevolumeandshape

Liquid – definitevolumeandchangingshape

Gas– changingvolumeandshape

I.ParticleModelofMatter

1)Allmatterismadeupofverysmallparticles

2)Therearespacesbetweentheparticles

3)Theparticles inmatterarealwaysmoving

4)Theparticlesareattractedtooneanother

II.KineticMolecularTheory

• Matter,chemicalchangesandthestatesofmatterareallpartofchemistry

KMT…• explainswhathappenstomatterwhenthekineticenergyofparticleschanges

*KineticEnergyistheenergyofmotion

KineticMolecularTheory…

1. Allmatterismadeupofsmallparticles

2. Thereisemptyspacebetweentheparticles

3. Particlesareconstantlymoving.Theparticlesarecollidingwitheachotherandthewallsoftheircontainer.

SOLIDS: particlesare tightlypacked;particlescannotmovearoundfreely,vibratinginplace

LIQUIDS: particlesareslightlyfurtherapart;particlescanslidebyeachother

GASES: particlesarefurtherapartandmovingquickly;particlescanmovefreely

KineticMolecularTheory…

4.Energymakesparticlesmove.Themoreenergytheparticleshave,thefastertheycanmoveandthefartheraparttheyget.

IV.ThermalExpansionandContraction• Whentemperature increases,kineticenergy

increases

• Particlesmovefasterandoveralargerregionrequiringmorespacebetweenparticles

• Substance“expands”– increasinginvolume

• Whentemperaturedecreases,kineticenergydecreases

• Particlesslowdown andtakeuplessspace

• Substance“contracts”– decreasinginvolume

V.Temperaturevs.Heat

• ThermalEnergy: totalenergyofalltheparticlesinasubstance

• Heat: thetransferofthermalenergyfromahottermaterialtoacoolerone

• Temperature: averagekineticenergyoftheparticles

VI.ChangeofState

• Meltingpointisthetemperatureatwhichsolidturnstoliquid.

• Boilingpointisthetemperatureatwhichliquidturnsintogas.

7.2FluidsandDensity

I.Solid,LiquidandGasDensity

• Fluid:matterthancanflow(liquidsorgases–notsolids!)

• Density: massofagivenvolume(howcloselypackedparticlesare)

• Mostsubstancesaremoredenseinsolidformthanliquidform…exceptwater

• Watermoleculesmoveslightlyapartwhentheylockintoplaceinicecrystals

• Thisiswhyicefloatsonwater

II.LayeringandMeasuringDensity

• Lessdensematerialfloatsontopofmoredensematerial

• Ifanobject:o floatsinafluid– lessdenseohoversinplace– samedensityosinksinafluid–moredense

III.Measuringvolume

Usearulerforregularlyshapedobjects

Volume=length x widthx height(measuredincm3)

UseDisplacementforirregularlyshapedobjects

• submergeobjectinafluidandmeasurethechangeofvolumeinthefluid

• thevolumeoftheobjectisthesameasthechangeinfluidvolume

IV.CalculatingDensity

1)A5mL sampleofmotoroilhasamassof4.5g.Whatisthedensityofthemotoroil?

2)Acarverbeginsworkonablockofgranitethatmeasures20cmby10cmby5cm.Iftheblockofgranitehasamassof2700g,whatisthedensityofthegranite?

3)Aluminumhasadensityof2.7g/cm3.Whatisthemassofa15cm 3 blockofaluminum?

4)Tablesalthasadensityof2.16g/mL.Howmanymillilitres ofsaltwouldyouhaveina500gpackage?

Section7.3DescribingMatter

I.PropertiesofMatter

• Properties (orcharacteristics)areusedtodifferentiateonetypeofmatterfromanother.– PHYSICAL propertiescanbeobservedormeasuredandarebrokendownintotwogroups:qualitativeandquantitative.

• QUALITATIVE: propertiesthatcanbedescribedbutnotmeasurede.g.state,colour,malleability (poundintosheets),ductility (pullintowires),crystallinity,magnetism

• QUANTITATIVE: propertiesthatcanbemeasuredusingnumberse.g.solubility(dissolvesinwater),conductivity,viscosity,density,melting/freezingpoint,boiling/condensingpoint

• Mattercanbeorganizedindifferenttypes.

• APURESUBSTANCE isasubstancemadeupofonlyonekindofmatter.Ex.gold,water,andoxygen.

• Anelement isapuresubstancethatcannotbebrokendownorseparatedintosimplersubstances.

Ex.goldandoxygen.WaterisNOTanelementbecauseitcanbebrokendownintohydrogenandoxygen

• Acompound isapuresubstancecomposedofatleasttwoelementscombinedinaspecificway.

Ex.water.

• Amixture ismorethanonesubstancecombinedtogether

Either• Elementandelement• Elementandcompound• Compoundandcompound

Statewhetherthefollowingareanelement,acompound,amixtureoftwoelements,amixtureoftwocompounds,oramixtureofanelement

andacompoundA

B

C

D

E

F

G

H

I

II.Mattercanalsochange:

PhysicalChange• Thepropertieswillremainthesame (orcanreturntotheoriginal)

• Nonew substanceisproduced• Caneasilychange back• Examples:changeofstate,dissolving,mixing

ChemicalChange• Product(whatyouendwith)isdifferentfromthereactant(startingmatter)• Hardorimpossibletoreverse• Examples:newcolour,heatorlightgivenoff,bubbles

• Circlethephysicalchanges: