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Chapter 1Chapter 1Chemistry: The Study of MatterChemistry: The Study of Matter

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What is Chemistry?What is Chemistry?The study of the matter, its composition, The study of the matter, its composition, properties, and the changes it properties, and the changes it undergoes.undergoes.Applied Chemistry is the using Applied Chemistry is the using chemistry to attain certain goals, in chemistry to attain certain goals, in fields like medicine, agriculture, and fields like medicine, agriculture, and manufacturingmanufacturingPure chemistry gathers knowledge for Pure chemistry gathers knowledge for knowledge sakeknowledge sake

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Types of ChemistryTypes of ChemistryAnalytical Chemistry studies Analytical Chemistry studies composition of substances.composition of substances.Inorganic Chemistry substances without Inorganic Chemistry substances without carboncarbonOrganic Chemistry compounds Organic Chemistry compounds containing carboncontaining carbonBiochemistryBiochemistry-- Chemistry of living thingsChemistry of living thingsPhysical Chemistry studies behavior of Physical Chemistry studies behavior of substancessubstances

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Chemistry isChemistry isA natural science.A natural science.a language with its own vocabulary.a language with its own vocabulary.a way of thinking.a way of thinking.

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Scientific MethodScientific MethodA way of solving problems or answering A way of solving problems or answering questions.questions.Starts with observationStarts with observation-- noting an noting an recording factsrecording factsHypothesisHypothesis-- an an educatededucated guess as to guess as to the cause of the problem or answer to the cause of the problem or answer to the question.the question.

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Scientific MethodScientific MethodExperimentExperiment-- designed to test the designed to test the hypothesishypothesisonly two possible answersonly two possible answers–– hypothesis is righthypothesis is right–– hypothesis is wronghypothesis is wrong

Generates data observations from Generates data observations from experiments.experiments.Modify hypothesis Modify hypothesis -- repeat the cyclerepeat the cycle

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Observations

Hypothesis

Experiment

Cycle repeats many Cycle repeats many times.times.The hypothesis gets The hypothesis gets more and more more and more certain.certain.Becomes a Becomes a theorytheoryA thoroughly tested A thoroughly tested model that explains model that explains why things behave a why things behave a certain way.certain way.

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Theory can never Theory can never be proven.be proven.Useful because Useful because they predict they predict behaviorbehaviorHelp us form mental Help us form mental pictures of pictures of processes (processes (modelsmodels))

Observations

Hypothesis

Experiment

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Another outcome is Another outcome is that certain behavior that certain behavior is repeated many is repeated many timestimesScientific Scientific LawLaw is is developeddevelopedDescription of how Description of how things behave things behave Law Law -- howhowTheoryTheory-- whywhy

Observations

Hypothesis

Experiment

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Law

Theory(Model)

Prediction

Experiment

Modify

Observations

Hypothesis

Experiment

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What is Matter?What is Matter?MatterMatter is anything that takes up space is anything that takes up space and has mass.and has mass.MassMass is the amount of matter in an is the amount of matter in an object.object.Mass is resistance to change in motion Mass is resistance to change in motion along a smooth and level surface.along a smooth and level surface.

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Types of MatterTypes of MatterSubstanceSubstance-- a particular kind of matter a particular kind of matter --purepureMixtureMixture-- more than one kind of mattermore than one kind of matter

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PropertiesPropertiesWords that describe matter (adjectives)Words that describe matter (adjectives)Physical PropertiesPhysical Properties-- a property that can a property that can be observed and measured without be observed and measured without changing the substance.changing the substance.Examples?Examples?Chemical PropertiesChemical Properties-- a property that a property that can only be observed by changing the can only be observed by changing the type of substance. type of substance.

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States of matterStates of matterSolidSolid-- mater that can not flow and has mater that can not flow and has definite volume.definite volume.LiquidLiquid-- definite volume but takes the definite volume but takes the shape of its container (flows).shape of its container (flows).GasGas-- a substance without definite a substance without definite volume or shape and can flow.volume or shape and can flow.VaporVapor-- a substance that is currently a a substance that is currently a gas but normally is a liquid or solid at gas but normally is a liquid or solid at room temperature.room temperature.

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States of MatterStates of Matter

Solid

Liquid

Gas

Definite Volume?

YES

YES

NO

Definite Shape?

YES

NO

NO

Temp. increaseSmall Expans.

Small Expans.

Large Expans.

Com-pressible?

NO

NO

YES

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Solid Liquid Gas

Melt Evaporate

CondenseFreeze

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Physical ChangesPhysical ChangesA change that changes appearances, A change that changes appearances, without changing the composition.without changing the composition.Examples?Examples?Boiled water is still water.Boiled water is still water.Chemical changes Chemical changes -- a change where a a change where a new form of matter is formed.new form of matter is formed.Examples?Examples?

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MixturesMixturesMade up of two substances.Made up of two substances.Variable composition?Variable composition?HeterogeneousHeterogeneous-- mixture is not the same mixture is not the same from place to place.from place to place.Chocolate chip cookie, gravel, soil.Chocolate chip cookie, gravel, soil.HomogeneousHomogeneous-- same composition same composition throughout.throughout.KoolKool--aid, air.aid, air.Every part keeps its properties.Every part keeps its properties.

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SolutionsSolutionsHomogeneous mixtureHomogeneous mixtureMixed molecule by moleculeMixed molecule by moleculeCan occur between any state of matter.Can occur between any state of matter.Solid in liquidSolid in liquid-- KoolKool--aidaidLiquid in liquidLiquid in liquid-- antifreezeantifreezeGas in gasGas in gas-- airairSolid in solid Solid in solid -- brassbrassLiquid in gasLiquid in gas-- water vaporwater vapor

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SolutionsSolutionsLike all mixtures, they keep the Like all mixtures, they keep the properties of the components.properties of the components.Can be separated by physical meansCan be separated by physical meansNot easily separatedNot easily separated-- cancan be separated.be separated.

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SubstancesSubstancesElementsElements-- simplest kind of mattersimplest kind of matterCannot be broken down into simplerCannot be broken down into simplerAll one kind of atom.All one kind of atom.CompoundsCompounds are substances that can be are substances that can be broken down by chemical methodsbroken down by chemical methodsWhen they are broken down, the pieces When they are broken down, the pieces have completely different properties have completely different properties than the compound.than the compound.Made of Made of moleculesmolecules-- two or more atoms two or more atoms

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Compound or MixtureCompound or MixtureCompound Mixture

One kind of piece-Molecules

More than one kind -Molecule or atoms

Making is a chemical change

Making is a physical change

Only one kind Variable composition

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Which is it?Which is it?

ElementCompoundMixture

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Chemical symbolsChemical symbolsThere are 109 elementsThere are 109 elementsEach has a 1 or two letter Each has a 1 or two letter symbolsymbolFirst letter always capitalized second First letter always capitalized second neverneverDonDon’’t need to memorizet need to memorizeSome from Latin of other languagesSome from Latin of other languages

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EnergyEnergyThe ability to do The ability to do work.work.Work Work -- cause a change or move an cause a change or move an object.object.Many typesMany types-- all can be changed into the all can be changed into the other.other.

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Types of energyTypes of energyPotentialPotential-- stored energystored energyKinetic EnergyKinetic Energy-- energy something has energy something has because its movingbecause its movingHeatHeat-- the energy that moves because of the energy that moves because of a temperature difference.a temperature difference.Chemical energyChemical energy-- energy released or energy released or absorbed in a chemical change.absorbed in a chemical change.Electrical energy Electrical energy -- energy of moving energy of moving chargescharges

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Types of EnergyTypes of EnergyRadiant EnergyRadiant Energy-- energy that can travel energy that can travel through empty space (light, UV, through empty space (light, UV, infrared, radio)infrared, radio)All types of energy can be converted All types of energy can be converted into others.into others.If you trace the source far enough back, If you trace the source far enough back, you will end up at nuclear energy.you will end up at nuclear energy.

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Conservation of EnergyConservation of EnergyEnergy can be neither created or Energy can be neither created or destroyed in ordinary changes (not destroyed in ordinary changes (not nuclear), it can only change form.nuclear), it can only change form.Its not just a good idea, its the Its not just a good idea, its the lawlaw..

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Chemical ReactionsChemical ReactionsWhen one or more substances are When one or more substances are changed into new substances.changed into new substances.ReactantsReactants-- stuff you start withstuff you start withProductsProducts-- What you makeWhat you makeNEW PROPERTIESNEW PROPERTIESNot easily reversedNot easily reversed

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Indications of a chemical reactionIndications of a chemical reactionEnergy absorbed or releasedEnergy absorbed or releasedColor changeColor changeodor changeodor changePrecipitatePrecipitate-- solid that separates from solid that separates from solutionsolutionNot easily reversedNot easily reversed

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Conservation of Mass Conservation of Mass Mass can not be created or destroyed in Mass can not be created or destroyed in ordinary (not nuclear) changes.ordinary (not nuclear) changes.All the mass can be accounted for.All the mass can be accounted for.

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What about nuclear?What about nuclear?E = mcE = mc22

energy = mass x (speed of light)energy = mass x (speed of light)22

speed of light = 3 x 10speed of light = 3 x 1088

A little mass can make a lot of energyA little mass can make a lot of energyLaw of Conservation of Mass Law of Conservation of Mass -- EnergyEnergythe total of the mass and energy the total of the mass and energy remains the same in any changeremains the same in any change