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Key Terms for Chapter 4

Viscosity Boiling point

Absolute zeroCompressibility

KelvinAmorphous solid

SublimationCrystalline solid

Condensation Brownian movement

Bose-Einstein condensate Diffusion

EvaporationFreezing point

Melting pointCondensation point

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Chapter 4PROPERTIES OF MATTER

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Properties of Matter

Physical PropertiesA characteristic of the object/material (color, shape….)

Physical ChangesA change in a material that does not alter its identity

Chemical PropertiesDescribes how matter will react in the presence of other

matter Chemical Changes

Alters the identity of the material (iron rusting, burning wood)

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Physical Properties

Property that can be observed and measured without a change in the kind of matter being observed

Examples Color Density Shape Texture Hardness State or Phase Conductivity

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Physical Changes

Does not alter the identity of the material It is a change in a physical property It remains the same kind of matter Generally easy to reverse Atoms do not rearrange Ex.: cutting a piece of paper, freezing water…

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Chemical Properties

Describes how matter will react in the presence of other substances

Ex. The tendency of iron to rust

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Chemical Change

Alters the identity of the material and forms a new kind of matter

Generally called a chemical reaction Both physical and chemical properties change Atoms are rearranged: new chemical formula Generally not a reversible reaction Energy is often produced or absorbed Ex.: burning, rusting

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Physical or Chemical change?

Water evaporates into steam A piece of cork is cut in half A bicycle chain rusts A piece of apple rots on the ground

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Models

Ideas that represent what might be happening No model is perfect Models can change Good models

Organize ideas

Describe observations

Help us describe what we cannot see

Predict what will happen

Different types of models Solar system models

DNA

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Matter

Aristotle (and other Greek philosophers) believed that matter was continuous

It could be divided infinitely without changing it

This concept was generally accepted from about 500 B.C. for 1500 A.D

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Particle Model of Matter

Matter could only be subdivided to a certain point – eventually you would not be able to divide it any more

Ex. Water droplet Measure those particles in angstroms and

nanometers These particles are called atoms Two or more atoms joined together forms a molecule

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Particle Model

You can watch the diffusion of food coloring in water whether you stir it or let it sit

If you let it sit long enough, the solution will spread throughout the water without stirring. How?

Brownian Movement: describes the constant motion of particles in a liquid or gas1st introduced by a botanist Robert Brown

Diffusion: mixing by this particle motion

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Phases of Matter

4 phases of matterSolidLiquidGasPlasma

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Solid

Definite shape Definite volume Usually dense: particles are packed closely together Low compressibility Particles vibrating in fixed position Low kinetic energy: strong attractive force

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Solid

Occur in 2 basic forms:Crystalline: atoms are in a fixed, repeating

structure in solidAmorphous: atom arrangement is random

Ex. glass

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Liquid

Definite volume No definite shape Low compressibility Random particle movement: Brownian Motion Particles fairly close Fairly equal kinetic energy to attractive force Viscosity: the ease with which a liquid will flow

Low viscosity: liquid flows very easily (water) High viscosity: liquid does not flow easily (pancake syrup)

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Gas

Indefinite shape Indefinite volume High compressibility Particles are far apart More kinetic energy than attractive force Brownian motion Gas pressure: from the collisions of the gas particles with the

sides of the container (ex. Balloon) Heat gas = more kinetic energy

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Comparing Phases

Solid Liquid Gas

Volume Definite Definite Indefinite

Shape Definite Indefinite Indefinite

Compressibility Low Low High

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Bose-Einstein Condensate

Hypothetical phase of matter that exists at absolute zero

Particles of the object behave as a single atom Still being studied in labs to determine it’s uses

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Phase Changes of Matter

Temperature increases = energy increases Temperature decreases = energy decreases Adding and removing energy will result in a phase

change

The type of matter stays the same

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Phase Changes

Phase changes that add energy

MeltingVaporization

Boiling Evaporation

Sublimation

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Melting

Change from a solid to a liquid The temperature at which melting occurs is called

the melting point

Water: 0oC or 32oF

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Vaporization

Change from liquid to gas Boiling

Occurs very quicklyDepends on the air pressure aboveBoiling point: temperature at which substance boils

EvaporationOccurs very slowly

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Sublimation

Change from solid to gas (without becoming a liquid)

Solid particles gain enough energy to escape into the atmosphere

Ex. Dry ice, moth balls, snow

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Phase Changes

Phase changes that remove energyFreezingCondensingDeposition

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Freezing

Change from liquid to solid Liquid particles lose enough kinetic energy that the

attractive forces hold the particles in place Temperature at which this occurs is freezing point

Water: 0oC or 32oF

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Condensing

Change from gas to liquid Temperature at which this occurs is dew point

(condensation point)

Ex. Dew

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Deposition

Change from gas to solid (without becoming liquid)

Ex. Frost, Ice on wings of plane

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Measuring Energy

Temperature: Measure of average Kinetic energyDifferent than heat (total Kinetic energy)

Celsius: 0C Fahrenheit: 0F Kelvin: K Absolute zero: the temperature at which all

molecular motion would cease

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Conversions

C to K – add 273 K to C – subtract 273 C to F – (C x 1.8) + 32 F to C – (F – 32)/1.8

MEMORIZE THESE CONVERSIONS

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Conversions

Convert -182 oC to K

-182 + 273 = 91 K Convert 298 K to oC

298 – 273 = 25 oC Convert 68oF to oC

68-32 = 36/1.8 = 20 oC Convert 312 K to oF

312 – 273 = 39 oC

(39 x 1.8) +32 = 102.2 oF