Chapter 1Chapter 1Introduction to Introduction to

ChemistryChemistry

What you’ll learn…What you’ll learn…

You will describe the relationships You will describe the relationships between chemistry and matterbetween chemistry and matter

You will recognize how scientific You will recognize how scientific methods can be used to solve methods can be used to solve problemsproblems

You will distinguish between You will distinguish between scientific research and technology scientific research and technology

Chemistry and MatterChemistry and Matter

ChemistryChemistry is the study of is the study of mattermatter and the changes that it undergoesand the changes that it undergoes

MatterMatter is anything that is anything that has a has a massmass and and takes up spacetakes up space

MassMass is a measurement that is a measurement that reflects the reflects the amount of matteramount of matter Is air matter?Is air matter?

WeightWeight is a measurement not is a measurement not only of the only of the amount of matteramount of matter but also the effect of the but also the effect of the Earth’s Earth’s gravitational pull on that mattergravitational pull on that matter

Why would scientists use Why would scientists use “mass”“mass” instead of instead of “weight”“weight”? ?

Macroscopic vs. MicroscopicMacroscopic vs. Microscopic Macroscopic matter does not Macroscopic matter does not

need a microscope to see it need a microscope to see it whereas microscopic matter whereas microscopic matter needs a microscopeneeds a microscope

Submicroscopic= atoms Submicroscopic= atoms •FYI: 1 million million atoms could FYI: 1 million million atoms could fit onto the period at the end of a fit onto the period at the end of a sentencesentence

Scientific MethodsScientific Methods

ObservationsObservations Qualitative Data-Qualitative Data- information information

that that describesdescribes•Examples: color, odor, shapeExamples: color, odor, shape

Quantitative Data-Quantitative Data- numerical numerical informationinformation•Examples: how tall, how fast, Examples: how tall, how fast, how muchhow much

ExperimentsExperiments Independent variable-Independent variable- variable variable

that you plan to that you plan to changechange Dependent variable-Dependent variable- variable variable

that changes in that changes in responseresponse to a to a change in the independent variable change in the independent variable

Chapter 3Chapter 3Matter- Properties and Matter- Properties and

ChangesChanges

What about Chapter 2??? What about Chapter 2???

(We’ll come back to that…) (We’ll come back to that…)

Pure SubstancePure Substance

SubstanceSubstance- matter that has a - matter that has a uniformuniform and and unchanging unchanging compositioncomposition Examples: Table Salt, water, Examples: Table Salt, water,

sugarsugar

Physical Properties of MatterPhysical Properties of Matter

A A physical propertyphysical property can be can be observed or measured observed or measured without without changingchanging the sample’s the sample’s compositioncomposition Examples: Density, Color, Odor, Examples: Density, Color, Odor,

Taste, Hardness, Melting Point, Taste, Hardness, Melting Point, Boiling PointBoiling Point

Extensive vs. Intensive Extensive vs. Intensive PropertiesProperties

Extensive PropertiesExtensive Properties are are dependent upon the amount of dependent upon the amount of substance presentsubstance present Example: MassExample: Mass

Intensive PropertiesIntensive Properties are are independent of the amount of independent of the amount of substance presentsubstance present Example: Density, Color Example: Density, Color

Chemical Properties of Chemical Properties of MatterMatter

Chemical propertyChemical property -the ability -the ability of a substance to combine with of a substance to combine with or change into one or more other or change into one or more other substances substances Example: The ability of iron to Example: The ability of iron to

form rust when combined with form rust when combined with oxygenoxygen

States of MatterStates of Matter SolidSolid

Definite shapeDefinite shape Definite volumeDefinite volume

LiquidLiquid FlowsFlows Constant volumeConstant volume Takes the shape of its containerTakes the shape of its container

GasGas Flows to conform to the shape of its containerFlows to conform to the shape of its container Fills entire volume of containerFills entire volume of container VaporVapor- refers to the gaseous state of a - refers to the gaseous state of a

substance that is a solid or a liquid at room substance that is a solid or a liquid at room temperaturetemperature

Physical ChangePhysical Change

Physical Physical changeschanges alter a alter a substance substance without changing without changing its compositionits composition Example: cutting Example: cutting

a sheet of papera sheet of paper•Indicating words: Indicating words:

bend, grind, crush, bend, grind, crush, split, melting, split, melting, freezing, condensefreezing, condense

Chemical ChangesChemical Changes

AKA Chemical ReactionAKA Chemical Reaction A process that involves one A process that involves one

or more substances or more substances changing into new changing into new substancessubstances

Conservation of MassConservation of Mass

The law of conservation of The law of conservation of mass states that matter is mass states that matter is neither created nor destroyed neither created nor destroyed (it is conserved)(it is conserved)

WOOD + OXYGEN ASH + WATER VAPOR + CARBON DIOXIDE

Chemical or Physical Change?Chemical or Physical Change?

wind eroding rocks _________________________wind eroding rocks _________________________ dead leaves decaying __________________________dead leaves decaying __________________________ rain puddle drying up __________________________rain puddle drying up __________________________ mixing flour and baking powder__________________________mixing flour and baking powder__________________________ gasoline evaporating __________________________gasoline evaporating __________________________ hydrogen peroxide hydrogen peroxide

decomposing__________________________decomposing__________________________ bread baking in an oven __________________________bread baking in an oven __________________________ instant tea dissolving in water __________________________instant tea dissolving in water __________________________ milk souring __________________________milk souring __________________________ gasoline burning __________________________gasoline burning __________________________

ANSWERS

wind eroding rocks – wind eroding rocks – PHYSICAL CHANGEPHYSICAL CHANGE dead leaves decaying – dead leaves decaying – CHEMICAL CHANGECHEMICAL CHANGE rain puddle drying up – rain puddle drying up – PHYSICAL CHANGEPHYSICAL CHANGE mixing flour and baking powder- mixing flour and baking powder- PHYSICAL CHANGEPHYSICAL CHANGE gasoline evaporating – gasoline evaporating – PHYSICAL CHANGEPHYSICAL CHANGE hydrogen peroxide decomposing- hydrogen peroxide decomposing- CHEMICAL CHANGECHEMICAL CHANGE bread baking in an oven – bread baking in an oven – CHEMICAL CHANGECHEMICAL CHANGE instant tea dissolving in water – instant tea dissolving in water – PHYSICAL CHANGEPHYSICAL CHANGE milk souring – milk souring – CHEMICAL CHANGECHEMICAL CHANGE gasoline burning- gasoline burning- CHEMICAL CHANGECHEMICAL CHANGE

MixturesMixtures

A mixture is a combination of two or A mixture is a combination of two or more substances in which each pure more substances in which each pure substance retains its individual substance retains its individual chemical propertieschemical properties

HeterogeneousHeterogeneous Mixture- one that does Mixture- one that does not blend smoothly throughout and which not blend smoothly throughout and which the individual substances remain distinct the individual substances remain distinct

• Examples: Sand and Water, Oil and Water, Examples: Sand and Water, Oil and Water, CementCement

HomogeneousHomogeneous Mixture (Solutions)- has Mixture (Solutions)- has constant composition throughout; it always constant composition throughout; it always has a single phase has a single phase

• Examples: salt water, vinegar, alloysExamples: salt water, vinegar, alloys

Separating Mixtures

1. Filtration- technique that uses a porous barrier to separate a solid from a liquid

2. Distillation- technique that is based on differences in the boiling points of substances

3. Crystallization- technique that results in the formation of pure solid particles of a substance from a solution containing the dissolved substance

4. Chromatography- separates the components of a mixture on the basis of the tendency of each to travel or be drawn across the surface of another material

Elements and Compounds

Element- a pure substance that cannot be separated into simpler substances Located on the periodic table in rows and

periods• Periods= Horizontal Rows• Groups= Vertical Columns

Compound- a combination of two or more different elements that are combined chemically

Law of Definite Proportions

Elements comprising compounds combine in definite proportions

Regardless of the amount, a compound is always composed of the same elements in the same proportion by mass

Percent by Mass- the ratio of the mass of each element to the total mass of the compound as a percentage

x100compound of mass

element of mass(%) massby percent

Practice Problem

A 78.0g sample of an unknown compound contains 12.4 g of hydrogen. What is the percent by mass of hydrogen in the compound?

100x78.0g

12.4gmassby Percent

15.9% Hydrogen

Material Pure Substance or Mixture

Element, Compound, Homogeneous, Heterogeneous

Limestone (CaCO3)

Soil

Bronze

Aluminum

Sugar + water

Concrete

Sterling Silver

Caffeine

ANSWERS

Material Pure Substance or Mixture

Element, Compound, Homogeneous, Heterogeneous

Limestone (CaCO3)

PURE SUBSTANCE

COMPOUND

Soil MIXTURE HETEROGENOUS

Bronze MIXTURE HOMOGENOUS

Aluminum PURE SUBSTANCE

ELEMENT

Sugar + water MIXTURE HOMOGENOUS

Concrete MIXTURE HETEROGENOUS

Sterling Silver MIXTURE HOMOGEN

Caffeine PURE SUBSTANCE

COMPOUND

Homework

Page 9 #6-8,10

Page 13 #12

Page 60 #1-5

Page 69 #15-17

Page 76 #21-23

Page 77 #25-30 SKIP #28