Matter And Matter And EnergyEnergy

Chemistry I: Chapter 2a

Chemistry I Honors: Chapter 2

ICP: Chapter 15 & 16a

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The Nature of MatterThe Nature of MatterThe Nature of MatterThe Nature of Matter

Chemists are interested in the nature of matter Chemists are interested in the nature of matter and how this is related to its atoms and and how this is related to its atoms and molecules.molecules.

GoldGold MercuryMercury

Chemistry & Chemistry & MatterMatter

• We can explore the We can explore the MACROSCOPIC MACROSCOPIC world — what we world — what we can see — can see —

• to understand the to understand the PARTICULATEPARTICULATE worlds we cannot see.worlds we cannot see.

• We write We write SYMBOLSSYMBOLS to describe to describe these worlds.these worlds.

A Chemist’s View of A Chemist’s View of WaterWater

H2O (gas, liquid, solid)

MacroscopicMacroscopicMacroscopicMacroscopic

SymbolicSymbolicSymbolicSymbolicParticulateParticulateParticulateParticulate

A Chemist’s ViewA Chemist’s View

2 H2(g) + O2 (g) --> 2 H2O(g)

MacroscopicMacroscopicMacroscopicMacroscopic

SymbolicSymbolicSymbolicSymbolicParticulateParticulateParticulateParticulate

Kinetic Nature of Kinetic Nature of MatterMatter

Kinetic Nature of Kinetic Nature of MatterMatter

Matter consists of atoms Matter consists of atoms and molecules in _____.and molecules in _____.

STATES OF MATTERSTATES OF MATTERSTATES OF MATTERSTATES OF MATTER• ______________ — have rigid shape, fixed — have rigid shape, fixed

volume. External shape can reflect the volume. External shape can reflect the atomic and molecular arrangement.atomic and molecular arrangement.

–Reasonably well understood.Reasonably well understood.

• ______________ — have no fixed shape and may — have no fixed shape and may not fill a container completely. not fill a container completely.

–Not well understood.Not well understood.

• ______________ — expand to fill their container. — expand to fill their container.

–Good theoretical understanding.Good theoretical understanding.

OTHER STATES OF OTHER STATES OF MATTERMATTER

OTHER STATES OF OTHER STATES OF MATTERMATTER

•PLASMAPLASMA — an electrically charged — an electrically charged gas; Example: the sun or any other stargas; Example: the sun or any other star

•BOSE-EINSTEIN BOSE-EINSTEIN CONDENSATECONDENSATE — a condensate that — a condensate that forms near absolute zero that has forms near absolute zero that has superconductive properties; Example: superconductive properties; Example: supercooled Rb gassupercooled Rb gas

Physical Physical PropertiesProperties

What are some physical What are some physical properties?properties?

• colorcolor

• melting and boiling melting and boiling pointpoint

• odorodor

GraphiteGraphite — — layer structure layer structure of carbon of carbon atoms reflects atoms reflects physical physical properties.properties.

Physical ChangesPhysical Changes– can be observed without

changing the identity of the substance

Some Some physical changes physical changes would bewould be

• boiling of a liquidboiling of a liquid• melting of a solidmelting of a solid• dissolving a solid in a dissolving a solid in a

liquid to give a liquid to give a homogeneous mixture homogeneous mixture — a SOLUTION.— a SOLUTION.

Chemical Properties and Chemical Properties and Chemical ChangeChemical Change

• Chemical change Chemical change or or chemical reactionchemical reaction — — transformation of one or transformation of one or more atoms or molecules more atoms or molecules into one or more different into one or more different molecules.molecules.

•Burning hydrogen (HBurning hydrogen (H22) in ) in oxygen (Ooxygen (O22) gives H) gives H22O.O.

Sure Signs of a Sure Signs of a Chemical ChangeChemical Change

• HeatHeat

• LightLight

• Gas Produced Gas Produced (not from (not from boiling!)boiling!)

• Precipitate – a Precipitate – a solid formed by solid formed by mixing two mixing two liquids togetherliquids together

http://jchemed.chem.wisc.edu/JCESoft/CCA/CCA0/MOVIES/S1047.MOV

Physical vs. Chemical

• Examples:

– melting point

– flammable

– density

– magnetic

– tarnishes in air

physical

chemical

physical

physical

chemical

Physical vs. Chemical

• Examples:

– rusting iron

– dissolving in water

– burning a log

– melting ice

– grinding spices

Matter Flowchart

MATTER

Can it be physically separated?

Homogeneous Mixture

(solution)

Heterogeneous Mixture Compound

MIXTURE PURE SUBSTANCE

yes no

Can it be chemically decomposed?

noyesIs the composition uniform?

noyes

Colloids Suspensions

Element

Types of Mixtures

• Variable combination of 2 or more pure substances.

Heterogeneous –visibly separate phases

Homogeneous – Same throughout