Classifying MatterClassifying Matter

Let’s start small and work up Let’s start small and work up from there.from there.

• AtomAtom – the smallest unit of an – the smallest unit of an element that maintains the element that maintains the properties of the elementproperties of the element

• The can be physically The can be physically mixedmixed or or chemically chemically joinedjoined to make up other to make up other forms of matterforms of matter

Pure SubstancePure Substance

• A sample of matter, either a single A sample of matter, either a single elementelement or a single or a single compoundcompound, that has , that has definite definite chemicalchemical and and physicalphysical properties properties

Figure 14, Page 22

PhysicalPhysical Properties Properties

• Characteristic of a substance that Characteristic of a substance that does not involve a does not involve a chemicalchemical changechange

• Examples: Examples: Density, color, hardnessDensity, color, hardness• Does this test change the chemical Does this test change the chemical

make-up of the material?make-up of the material?• NoNo

ChemicalChemical Property Property• Characteristic of matter that Characteristic of matter that

describes a substance’s ability to describes a substance’s ability to participate in participate in chemicalchemical reactions reactions

• Example: Oxidation, flammability, Example: Oxidation, flammability, and combustionand combustion

• Does this test change the chemical Does this test change the chemical make-up of the material?make-up of the material?

• YesYes

Figure 12, page 19Figure 12, page 19

ElementsElements

• A A purepure substance that contains only substance that contains only oneone kind of atom kind of atom

• It cannot be It cannot be separatedseparated or or brokenbroken down down into simpler substances by into simpler substances by chemicalchemical means.means.

• All atoms of the same All atoms of the same elementelement have the have the same same atomicatomic number number

• Elements may bond in different ratios Elements may bond in different ratios with itself. These are called with itself. These are called allotropesallotropes..

CompoundsCompounds

• A A purepure substance that is made up of substance that is made up of two or more two or more differentdifferent elements elements joined by chemical bonds.joined by chemical bonds.

• They are represented by They are represented by formulasformulas

MoleculesMolecules

• The The smallestsmallest unit of a substance that unit of a substance that keeps all of the keeps all of the physicalphysical and and chemicalchemical properties of that substance.properties of that substance.

• It can consist of one atom or two or It can consist of one atom or two or more atoms bonded togethermore atoms bonded together

• In other words, molecules can be of In other words, molecules can be of the same the same elementelement or of the same or of the same compound compound only only

All of the following are All of the following are molecules, but are they molecules, but are they compounds or elements?compounds or elements?• BrBr22

• HH22OO

• OO22

• OO33

• CC1212HH2222OO1212

Element

Compound

Element

Element

Compound

MixturesMixtures

• A A combinationcombination of two or more of two or more substances that are substances that are notnot chemically chemically combined.combined.

• Examples are Examples are air, ice tea, and even air, ice tea, and even cake battercake batter

• The The proportionsproportions of the substances of the substances can can varyvary

Mixtures can be Mixtures can be homogeneoushomogeneous or or heterogeneousheterogeneous• HomogeneousHomogeneous mixtures have a mixtures have a

uniformuniform structure or composition structure or composition throughoutthroughout

• Because of the even distribution, any Because of the even distribution, any two samples taken from the same two samples taken from the same homogenoushomogenous mixture will have the mixture will have the samesame proportions of ingredients proportions of ingredients

• Examples: Examples: Gasoline, air, and syrupGasoline, air, and syrup

Mixtures can be homogeneous Mixtures can be homogeneous or heterogeneousor heterogeneous

• HeterogeneousHeterogeneous mixtures are mixtures are notnot evenly mixed.evenly mixed.

• Different regions of the same Different regions of the same heterogeneousheterogeneous mixture will have mixture will have differentdifferent proportions proportions

• Examples: Examples: Pulpy Orange Juice, Pulpy Orange Juice, chocolate chip cookie dough, and chocolate chip cookie dough, and granite.granite.

Visuals of Homogeneous and Visuals of Homogeneous and Heterogeneous MixturesHeterogeneous Mixtures

Figure 19, Page 26

Mixtures verses Compounds, Mixtures verses Compounds, How can you tell which is How can you tell which is which?which?• CompoundsCompounds are two or more are two or more

elements that are elements that are chemicallychemically bonded bonded together.together.

• MixturesMixtures are two or more substances are two or more substances physicallyphysically mixed together, but not mixed together, but not chemicallychemically joined joined

ThereforeTherefore

• Properties of a Properties of a mixturemixture reflect the reflect the properties of the properties of the substancessubstances mixed mixed in it; in it; compoundscompounds have have newnew properties of their own.properties of their own.

• Compounds have Compounds have definitedefinite composition; mixtures composition composition; mixtures composition can can varyvary from mixture to mixture from mixture to mixture of the same substancesof the same substances

In other words,In other words,

• You can have a mixture of hydrogen You can have a mixture of hydrogen gas and oxygen gas in various gas and oxygen gas in various concentrations, but the compound concentrations, but the compound water, Hwater, H22O, will always have 2 O, will always have 2 hydrogen atoms bonded to one hydrogen atoms bonded to one oxygen atom.oxygen atom.

Figure 20, Page 28Figure 20, Page 28

Classify each of the following as Classify each of the following as an element, compound, an element, compound, homogeneous mixture, or a homogeneous mixture, or a heterogeneous mixtureheterogeneous mixture

• Iron (III) Oxide (FeIron (III) Oxide (Fe22OO33))

• 24 Karat gold24 Karat gold

• Sugar WaterSugar Water

• OzoneOzone

• Fizzy SodaFizzy Soda

• Flat SodaFlat Soda

Element

Element

Heterogeneous Mix

Homogeneous Mix

Homogeneous Mix

Compound

Separating MixturesSeparating Mixtures

Since mixtures are just physically Since mixtures are just physically combined, they can be combined, they can be separatedseparated..

Separating MixturesSeparating Mixtures• Some Methods include:Some Methods include:

– FilteringFiltering – – separation of a mixture’s components through differences in particle size

– DecantingDecanting – a fancy term for separating two components by – a fancy term for separating two components by pouringpouring

– DistillationDistillation – used to separate two liquids based on their – used to separate two liquids based on their differences in boiling pointsdifferences in boiling points

– MagnetismMagnetism – used to separate magnetic substances – used to separate magnetic substances– EvaporationEvaporation – removing a liquid to leave a solid behind – removing a liquid to leave a solid behind– CentrifugeCentrifuge – separates substances of different densities – separates substances of different densities

using a fast rotational motionusing a fast rotational motion– ChromatographyChromatography – Separates two substances by using a – Separates two substances by using a

mobile phase and a stationary phasemobile phase and a stationary phase