Matter And Matter And EnergyEnergy

An IntroductionAn IntroductionSAVE PAPER AND INK!!! When you print out the notes on PowerPoint, print "Handouts" instead

of "Slides" in the print setup. Also, turn off the backgrounds (Tools>Options>Print>UNcheck "Background Printing")!

The 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. More on this later in the coursemolecules. More on this later in the course

GoldGold MercuryMercury

Kinetic Nature of Kinetic Nature of MatterMatterMatter consists of atoms and molecules in motion Matter consists of atoms and molecules in motion

to varying degrees: from vibrating around a fixed to varying degrees: from vibrating around a fixed point to moving independent of all otherspoint to moving independent of all others

STATES OF MATTERSTATES OF MATTER•SOLIDSSOLIDS — 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.

•LIQUIDSLIQUIDS — have no fixed shape and — have no fixed shape and may not fill a container completely. may not fill a container completely. –Not well understood.Not well understood.

•GASESGASES — expand to fill their container. — expand to fill their container. –Good theoretical understanding.Good theoretical understanding.

Physical Physical PropertiesPropertiesWhat are some physical What are some physical

properties?properties?• colorcolor• melting and boiling melting and boiling

pointpoint• odorodor

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

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

MATTERCan 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