Chapter 2: Properties of Matter

Chapter 2: Properties of Chapter 2: Properties of MatterMatter

Section 2.1 Classifying MatterSection 2.1 Classifying MatterSection 2.2 Physical PropertiesSection 2.2 Physical PropertiesSection 2.3 Chemical PropertiesSection 2.3 Chemical Properties

Section 2.1: Classifying Section 2.1: Classifying MatterMatter

Pure SubstancesPure Substances What is Matter? Anything that has What is Matter? Anything that has

mass and takes up space (volume)mass and takes up space (volume) Based on matter’s composition, it Based on matter’s composition, it

can be divided into can be divided into Pure Substances Pure Substances and Mixtures.and Mixtures.


Pure SubstancesPure Substances Def.-matter that always has exactly the same Def.-matter that always has exactly the same

composition (ex. Table salt, table sugar)composition (ex. Table salt, table sugar) Key Concept: Key Concept: Every sample of a given Every sample of a given

substance has the same properties because substance has the same properties because a substance has a fixed, uniform a substance has a fixed, uniform composition.composition.

2 Categories of substances: 2 Categories of substances: elements and elements and compoundscompounds


ElementsElements Def.-a substance that cannot be Def.-a substance that cannot be

broken down into simpler substancesbroken down into simpler substances Key Concept: Key Concept: An element has a fixed An element has a fixed

composition because it contains only composition because it contains only one type of atom.one type of atom.


Elements: Examples of ElementsElements: Examples of Elements Carbon (C), Aluminum (Al)- solid at Carbon (C), Aluminum (Al)- solid at

RTRT Oxygen (O), Nitrogen (N)- gases at Oxygen (O), Nitrogen (N)- gases at

RTRT Bromine (Br), Mercury (Hg)- liquid at Bromine (Br), Mercury (Hg)- liquid at

RTRT


Elements: Symbols for ElementsElements: Symbols for Elements Developed in 1813 by Swedish Developed in 1813 by Swedish

chemist Jchemist Jons Berzeliusons Berzelius Symbols contain 1 or 2 lettersSymbols contain 1 or 2 letters Symbols based on Latin names of the Symbols based on Latin names of the

elementselements


CompoundsCompounds Def.-Def.-a substance that is made from a substance that is made from

two or more simpler substances and two or more simpler substances and can be broken down into those can be broken down into those simpler substances (elements or simpler substances (elements or other compounds)other compounds)

HH22OO→→2H + O2H + O


CompoundsCompounds Properties of a compound differ from Properties of a compound differ from

the properties of the substances the properties of the substances from which it is made.from which it is made.

Ex. H and O are gases at room Ex. H and O are gases at room temp.; Htemp.; H22O is liquid at room temp.O is liquid at room temp.


CompoundsCompounds Key Concept: Key Concept: A compound always A compound always

contains two or more elements joined contains two or more elements joined in a fixed proportion.in a fixed proportion.

Ex. SiOEx. SiO22- 2 (O) atoms for every 1 (Si) - 2 (O) atoms for every 1 (Si) atomatom

Ex. HEx. H22O-2 (H) atoms for every 1 (O) O-2 (H) atoms for every 1 (O) atomatom

Elements vs. CompoundsElements vs. Compounds

If you see the If you see the chemical formula for chemical formula for an element what do an element what do you notice?you notice?

PbPb KK LiLi HH22

OO22

What is different What is different on these formula’s on these formula’s of compounds?of compounds?

HH22OO COCO22

CC66HH1212OO66

LiClLiCl NaClNaCl


MixturesMixtures 2 types: 2 types: heterogeneous and heterogeneous and

homogeneoushomogeneous Retain some of the properties of their Retain some of the properties of their

individual substancesindividual substances Properties of a mixture are less Properties of a mixture are less

constant (vary) than the properties of constant (vary) than the properties of a substance.a substance.


MixturesMixtures Key Concept: The properties of a Key Concept: The properties of a

mixture can vary because the mixture can vary because the composition of a mixture is not fixed.composition of a mixture is not fixed.

**Mixtures can be classified by how **Mixtures can be classified by how well the parts of the mixture are well the parts of the mixture are distributed throughout the mixture.distributed throughout the mixture.

Section 2.1 Classifying Section 2.1 Classifying MatterMatter

Mixtures: Heterogeneous and Mixtures: Heterogeneous and Homogeneous MixturesHomogeneous Mixtures

Heterogeneous- the parts of the mixture Heterogeneous- the parts of the mixture are noticeably different from one anotherare noticeably different from one another

Ex. SandEx. Sand Homogeneous-the substances are so Homogeneous-the substances are so

evenly distributed that it is difficult to evenly distributed that it is difficult to distinguish one substance in the mixture distinguish one substance in the mixture from anotherfrom another

Ex. Water, steelEx. Water, steel

MixturesMixtures

A mixture made up of A mixture made up of particles that are particles that are uniformly distributed uniformly distributed (means that you cant (means that you cant see the separate parts)see the separate parts)

Ex. Salt waterEx. Salt water In the ocean you cant In the ocean you cant

see the salt dissolved see the salt dissolved in the waterin the water

A mixture made up of A mixture made up of particles that are not particles that are not uniformly distributed uniformly distributed (normally you can (normally you can easily see the separate easily see the separate parts)parts)

Ex. Raisin BranEx. Raisin Bran You can see the You can see the

Raisins, flakes, and the Raisins, flakes, and the milk.milk.


Solutions, Suspensions, and ColloidsSolutions, Suspensions, and Colloids The size of the particles in a mixture The size of the particles in a mixture

has an effect on the properties of the has an effect on the properties of the mixture.mixture.

Key Concept: Key Concept: Based on the size of its Based on the size of its largest particles, a mixture can be largest particles, a mixture can be classified as aclassified as a solutionsolution, a , a suspensionsuspension, , or a or a colloidcolloid..


SolutionsSolutions Def.-Def.-the mixture that forms when the mixture that forms when

substances dissolve and form asubstances dissolve and form a homogeneous mixturehomogeneous mixture

Ex. Sugar water, salt water, Ex. Sugar water, salt water, lemonadelemonade


SolutionsSolutions *They do not separate into distinct *They do not separate into distinct

layers over time.layers over time. *They cannot be filtered.*They cannot be filtered. *Light passes through them.*Light passes through them. The particles in a solution are too The particles in a solution are too

small to settle out of the solution, be small to settle out of the solution, be trapped by a filter, or scatter light.trapped by a filter, or scatter light.


SuspensionsSuspensions Def.-Def.-a heterogeneous mixture that a heterogeneous mixture that

separates into layers over timeseparates into layers over time Ex. Amoxicillin, muddy waterEx. Amoxicillin, muddy water


SuspensionsSuspensions **Suspended particles settle outSuspended particles settle out of a of a

mixture or mixture or are trapped by a filterare trapped by a filter They They scatter light in all directions scatter light in all directions

because the particles are largebecause the particles are large; ; suspensions are cloudy.suspensions are cloudy.

Section 2.1: Classifying Section 2.1: Classifying MatterMatter ColloidsColloids

Def.-Def.-a mixture that contains some a mixture that contains some particles that are intermediate in size particles that are intermediate in size between the small particles in between the small particles in solution and larger particles in a solution and larger particles in a suspensionsuspension

Ex. Milk, fogEx. Milk, fog

Section 2.1 Classifying Section 2.1 Classifying MatterMatter ColloidsColloids

Do not separate into layersDo not separate into layers Cannot be filteredCannot be filtered Since they also contain larger Since they also contain larger

particles, they scatter lightparticles, they scatter light

Section 2.2 Physical Section 2.2 Physical PropertiesProperties

Examples of Physical PropertiesExamples of Physical Properties Def.-any characteristic of a material that Def.-any characteristic of a material that

can be observed or measured can be observed or measured without without changing the composition of the changing the composition of the substances in the materialsubstances in the material

Key Concept: Key Concept: ViscosityViscosity, , conductivityconductivity, , malleabilitymalleability, , hardnesshardness, , melting pointmelting point, , boiling pointboiling point, and , and densitydensity are examples of are examples of physical properties.physical properties.

Section 2.2: Physical Section 2.2: Physical PropertiesProperties ViscosityViscosity

Def.-the tendency of a liquid to keep Def.-the tendency of a liquid to keep from flowing (from flowing (its resistance to flowingits resistance to flowing))

>viscosity, the slower the liquid moves>viscosity, the slower the liquid moves Ex. Corn syrup, honey (high viscosity)Ex. Corn syrup, honey (high viscosity) Ex. Water (low viscosity)Ex. Water (low viscosity) Viscosity usually decreases when a Viscosity usually decreases when a

liquid is heated.liquid is heated.

Section 2.2 Physical Section 2.2 Physical PropertiesProperties ConductivityConductivity

Def.-Def.-a material’s ability to allow heat a material’s ability to allow heat flowflow

Conductor-materials that have Conductor-materials that have high high conductivity (ex. Metals)conductivity (ex. Metals)

Ex. Poor conductor (wood)Ex. Poor conductor (wood)

Section 2.2: Physical Section 2.2: Physical PropertiesProperties MalleabilityMalleability

Def.-Def.-the ability of a solid to be the ability of a solid to be hammered without shatteringhammered without shattering

Ex. Ex. Most metals are malleableMost metals are malleable; glass ; glass shatters (brittle)shatters (brittle)

Section 2.2: Physical Section 2.2: Physical PropertiesProperties

HardnessHardness Ie. Can the material be Ie. Can the material be scratched scratched

easilyeasily? Can it be ? Can it be cut easilycut easily?? Diamond is one of the hardest known Diamond is one of the hardest known

materials (can cut glass and steel); materials (can cut glass and steel); aggregated diamond nanorods aggregated diamond nanorods (hardest; carbon-60 molecules)(hardest; carbon-60 molecules)

Stainless steel can scratch copperStainless steel can scratch copper


Melting and Boiling PointsMelting and Boiling Points Melting pt.-Melting pt.-the temp at which a the temp at which a

substance changes from solid to substance changes from solid to liquidliquid

Boiling pt.-Boiling pt.-the temp at which a the temp at which a substance boilssubstance boils


DensityDensity Def.-Def.-the ratio of the mass of a substance the ratio of the mass of a substance

to its volumeto its volume *can be used to test the purity of a *can be used to test the purity of a

substancesubstance Ex. Density of silver=10.5g/cmEx. Density of silver=10.5g/cm33 RT RT *if density of a coin is 9.9 g/cm*if density of a coin is 9.9 g/cm33 RT then: RT then:

1.) the coin is not silver or 2.) the coin 1.) the coin is not silver or 2.) the coin contains substances in addition to silvercontains substances in addition to silver


Using Physical PropertiesUsing Physical Properties Key Concept: Physical properties are Key Concept: Physical properties are

used to used to identify a materialidentify a material, to , to choose choose a material for a specific purposea material for a specific purpose, or , or to to separate the substances in a separate the substances in a mixture.mixture.


Using Physical Properties: Using Using Physical Properties: Using Properties to Identify MaterialsProperties to Identify Materials

Steps are similar to those used to test for Steps are similar to those used to test for puritypurity

1.1. Decide which properties to testDecide which properties to test2.2. Do tests on a sample of the unknownDo tests on a sample of the unknown3.3. Compare the results with the data Compare the results with the data

reported for known materialsreported for known materials ID of materials can be crucial to solving a ID of materials can be crucial to solving a

crime.crime.


Using Physical Properties: Using Using Physical Properties: Using Properties to Choose MaterialsProperties to Choose Materials

Properties determine which materials Properties determine which materials are chosen for which usesare chosen for which uses

What material is more durable? Is a What material is more durable? Is a material more comfortable?material more comfortable?


Using Properties to Separate Using Properties to Separate MixturesMixtures

Some properties can be used to Some properties can be used to separate mixturesseparate mixtures

Key Concept: Filtration and Key Concept: Filtration and distillation are two common distillation are two common separation methods.separation methods.


Using Properties to Separate Using Properties to Separate Mixtures: FiltrationMixtures: Filtration

Filtration- Filtration- a process that separates a process that separates materials based on the size of their materials based on the size of their particlesparticles

small pass through; large are small pass through; large are trappedtrapped


Using Properties to Separate Mixtures: Using Properties to Separate Mixtures: DistillationDistillation

Def.-Def.-a process that separates the substances a process that separates the substances in a solution based on their boiling pointsin a solution based on their boiling points

Ex. (making freshwater)-Water heated until Ex. (making freshwater)-Water heated until in gas form; then cooled back to a liquid and in gas form; then cooled back to a liquid and collected in a separate containercollected in a separate container

Water has a lower boiling point than Water has a lower boiling point than compounds dissolved in seawater.compounds dissolved in seawater.


Recognizing Physical ChangesRecognizing Physical Changes Physical change-what occurs when some Physical change-what occurs when some

of the properties of a material change, but of the properties of a material change, but the substances in the material remain the the substances in the material remain the samesame

WaterWater (liquid→gas); Bending metal (liquid→gas); Bending metal Actions: slice, cut, heatActions: slice, cut, heat **Some physical changes are reversible, **Some physical changes are reversible,

some are not (Cutting hair)some are not (Cutting hair)

Section 2.3 Chemical Section 2.3 Chemical PropertiesProperties

Observing Chemical PropertiesObserving Chemical Properties Chemical property-Chemical property-any ability to any ability to

produce a change in the composition produce a change in the composition of matterof matter

Key Concept: Chemical properties Key Concept: Chemical properties can be observed only when the can be observed only when the substances in a sample of matter are substances in a sample of matter are changing into different substances.changing into different substances.


Observing Chemical Properties: Observing Chemical Properties: FlammabilityFlammability

Def.-Def.-a material’s ability to burn in the a material’s ability to burn in the presence of oxygenpresence of oxygen

Not always a desired property: Not always a desired property: fabricsfabrics

Ex. Paper, fuels (highly flammable)Ex. Paper, fuels (highly flammable)


Observing Chemical Properties: Observing Chemical Properties: ReactivityReactivity

Def.-Def.-the property that describes how the property that describes how readily a substance combines readily a substance combines chemically with other substanceschemically with other substances

Oxygen-high reactivity; Nitrogen-low Oxygen-high reactivity; Nitrogen-low reactivityreactivity

Ex. Oxygen causes iron to rust; rust is Ex. Oxygen causes iron to rust; rust is brittle and weaker than ironbrittle and weaker than iron


Recognizing Chemical ChangesRecognizing Chemical Changes Chemical change- what occurs when a Chemical change- what occurs when a

substance reacts and forms one or more substance reacts and forms one or more new substancesnew substances

Key Concept: Three common types of Key Concept: Three common types of evidence for a chemical change are a evidence for a chemical change are a change in colorchange in color, , the production of a gasthe production of a gas, , and the and the formation of a precipitateformation of a precipitate..

Precipitate-any solid that forms and Precipitate-any solid that forms and separates from a liquid mixtureseparates from a liquid mixture


Is a Change Chemical or Physical?Is a Change Chemical or Physical? Can be difficult to distinguish one from the Can be difficult to distinguish one from the

otherother Ask the question: Ask the question: Are different substances Are different substances

present after the change takes place?present after the change takes place? No-No-physicalphysical; ; Yes-chemicalYes-chemical

Key Concept: Key Concept: When matter undergoes a When matter undergoes a chemical change the composition of the chemical change the composition of the matter changes.matter changes. When matter undergoes When matter undergoes a physical change, the composition of the a physical change, the composition of the matter remains the same.matter remains the same.

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Chapter 2: Properties of Matter