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Chapter 2Chapter 2

“Matter “Matter and and

Change”Change”

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MatterMatterMatterMatter is anything that: a) has is anything that: a) has

mass, and b) takes up spacemass, and b) takes up spaceMassMass is a measure of the amount is a measure of the amount

of “stuff” (or material) the object of “stuff” (or material) the object contains (don’t confuse this with contains (don’t confuse this with weight, a measure of gravity)weight, a measure of gravity)

VolumeVolume is a measure of the space is a measure of the space occupied by the objectoccupied by the object

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Describing MatterDescribing Matter Properties used to describe matter Properties used to describe matter

can be classified as:can be classified as:

1)1) ExtensiveExtensive – depends on the – depends on the amountamount of matter in the sample of matter in the sample

- Mass, volume, calories are examples- Mass, volume, calories are examples

2)2) IntensiveIntensive – depends on the – depends on the typetype of matter, not the amount presentof matter, not the amount present

- Hardness, Density, Boiling Point- Hardness, Density, Boiling Point

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Properties are…Properties are… Words 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 material’s composition.changing the material’s composition.

Examples- color, hardness, m.p., b.p.Examples- color, hardness, m.p., b.p. Chemical PropertiesChemical Properties- a property that - a property that

can only be observed by changing the can only be observed by changing the composition of the material. composition of the material.

Examples- ability to burn, decompose, Examples- ability to burn, decompose, ferment, react with, etc.ferment, react with, etc.

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States of matterStates of matter1)1) SolidSolid- matter that can not flow (definite - matter that can not flow (definite

shape) and has definite volume.shape) and has definite volume.

2)2) LiquidLiquid- definite volume but takes the - definite volume but takes the shape of its container (flows).shape of its container (flows).

3)3) GasGas- a substance without definite volume - a substance without definite volume or shape and can flow.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. (Which is correct: room temperature. (Which is correct: “water gas”, or “water vapor”?)“water gas”, or “water vapor”?)

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States of MatterStates of Matter

Solid

Liquid

Gas

Definite Volume?

YES

YES

NO

Definite Shape?

YES

NO

NO

Result of a Temperature Increase?

Small Expansion

Small Expansion

Large Expansion

Will it Compress?

NO

NO

YES

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44thth state: state: PlasmaPlasma - - formed at formed at high temperatures; ionized high temperatures; ionized

phase of matter as found in the phase of matter as found in the sunsun

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Solid Liquid Gas

Melt Evaporate

CondenseFreeze

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Physical vs. Chemical ChangePhysical vs. Chemical Change

Physical changePhysical change will change the visible will change the visible appearance, without changing the appearance, without changing the composition of the material.composition of the material.– Boil, melt, cut, bend, split, crackBoil, melt, cut, bend, split, crack

Chemical changeChemical change - a change where a - a change where a new form of matter is formed.new form of matter is formed.– Rust, burn, decompose, fermentRust, burn, decompose, ferment

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MixturesMixtures Mixtures are a physical blendMixtures are a physical blend of at of at

least two substances and they have least two substances and they have variable composition. Two types:variable composition. Two types:

1)1) Heterogeneous Heterogeneous – this mixture is not – this mixture is not uniform in compositionuniform in composition

• Chocolate chip cookie, gravel, soil.Chocolate chip cookie, gravel, soil.2)2) Homogeneous Homogeneous - same composition - same composition

throughout; called “throughout; called “solutionssolutions””• Kool-aid, air, salt waterKool-aid, air, salt water

Every part keeps it’s own properties.Every part keeps it’s own properties.

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Phase?Phase? The term “phase” is used to describe The term “phase” is used to describe

any part of a sample with uniform any part of a sample with uniform composition of properties.composition of properties.

A homogeneous mixture consists of a A homogeneous mixture consists of a singlesingle phase phase

A heterogeneous mixture consists of A heterogeneous mixture consists of two or moretwo or more phases. phases.

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Separating MixturesSeparating Mixtures

Differences in physical properties Differences in physical properties can be used to separate mixtures.can be used to separate mixtures.

FiltrationFiltration - separates a solid from - separates a solid from the liquid in a heterogeneous the liquid in a heterogeneous mixture (by size) mixture (by size)

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Separation of a MixtureSeparation of a MixtureComponents of dyes such as ink may be separated by paper chromatography using the property of solubility.

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Separation of a MixtureSeparation of a MixtureDistillation: takes advantage of different boiling points.

NaCl boils at 1415 oC

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Pure SubstancesPure Substances Pure Substances are

either:

a) elements, or

b) compounds

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ElementsElements

ElementsElements - simplest kind of matter- simplest kind of matter

–cannot be broken down any simpler cannot be broken down any simpler and still have properties of that and still have properties of that element!element!

– elements are all elements are all oneone kind of atom. kind of atom.

Examples: carbon (C), hydrogen (H)Examples: carbon (C), hydrogen (H)

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CompoundsCompounds CompoundsCompounds are substances that can be are substances that can be

broken down broken down onlyonly by chemical means by chemical means

– when broken down, the pieces have when broken down, the pieces have completely different properties than the completely different properties than the original compound.original compound.

– made of made of two or moretwo or more atoms, chemically atoms, chemically combined (not just a physical blend!)combined (not just a physical blend!)

Examples: water (HExamples: water (H22O), carbon dioxide O), carbon dioxide

(CO(CO22))

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Compound vs. MixtureCompound vs. Mixture

Compound Mixture

Made of one kindof material

Made of more thanone kind of material

Made by a chemical change

Made by a physical change

Definitecomposition

Variablecomposition

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Which is it?Which is it?

A mixture or compound?

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Elements vs. CompoundsElements vs. Compounds

Compounds Compounds cancan be broken down be broken down into simpler substances by a into simpler substances by a chemical change, but chemical change, but elements elements

cannotcannot be broken down into a be broken down into a simpler substance. (subatomic simpler substance. (subatomic particles are not substances)particles are not substances)

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Properties of CompoundsProperties of Compounds Compounds have different properties Compounds have different properties

than their component elements.than their component elements.

• Table sugar (CTable sugar (C1212HH2222OO1111); carbon is a ); carbon is a

black solid, hydrogen is a odorless gas, black solid, hydrogen is a odorless gas, and oxygen is a colorless, flammable and oxygen is a colorless, flammable gas.gas.

• Sodium chloride (NaCl); sodium is a soft Sodium chloride (NaCl); sodium is a soft solid and chlorine is a green, toxic gassolid and chlorine is a green, toxic gas

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Classification of MatterClassification of Matter

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Symbols & FormulasSymbols & Formulas

Elements are represented using a 1 or two Elements are represented using a 1 or two letter letter symbolsymbol, and compounds are , and compounds are represented by represented by formulasformulas..

An element’s first letter always capitalized; An element’s first letter always capitalized; if there is a second letter, it is written if there is a second letter, it is written lowercase: C, Ca, H, Helowercase: C, Ca, H, He

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Chemical Reactions are…Chemical Reactions are…

One or more substances are changed One or more substances are changed into new substances.into new substances.

ReactantsReactants – what you start with – what you start with ProductsProducts- what you make- what you make The products will have NEW The products will have NEW

PROPERTIES different from the PROPERTIES different from the reactantsreactants

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Recognizing Chemical ChangesRecognizing Chemical Changes

1)1) EnergyEnergy is absorbed or released is absorbed or released (temperature changes hotter or colder)(temperature changes hotter or colder)

2)2) ColorColor changes changes

3)3) GasGas production (bubbling, fizzing, or production (bubbling, fizzing, or odor change; smoke)odor change; smoke)

4)4) Formation of aFormation of a precipitateprecipitate - a solid that - a solid that separates from solution (won’t dissolve)separates from solution (won’t dissolve)

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Law of Conservation of MassLaw of Conservation of Mass

During any chemical reaction, the During any chemical reaction, the mass of the products always equal mass of the products always equal the mass of the reactants.the mass of the reactants.

Mass is neither created or destroyed Mass is neither created or destroyed during a chemical reaction. during a chemical reaction.

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reactants = product

43.43 g Original mass = 43.43 g Final mass