States of MatterBy: Ms. Buroker

Let’s Review …. Shall We?

Kinetic Theory1.) All matter is made of atoms and

molecules that act like tiny particles.2.) These tiny particles are always in

motion. The higher the temperature of the substance, the faster the particles move.

3.) At the same temperature, more- massive (heavier) particles move slower than less massive (lighter) particles.

What does this suggest about solid particles vs. gas particles???

• )

State of Matter: Solids

Solids have …1.) low KE - particles vibrate but can’t move around2.) definite shape & volume3.) crystalline - repeating geometric pattern4.) amorphous - no pattern (e.g. glass, wax

State of Matter: Liquids

Liquids have …1.) higher KE - particles can move around but are still close together2.) indefinite shape3.) definite volume

All liquids are considered fluids because their particles can move past one another!

State of Matter: Gases

Gases have …1.) high KE - particles can separate and move throughout container2.) indefinite shape & volume

All gases are considered fluids because their particles can move past one another!

State of Matter: Plasma

Plasma has …1.) very high KE - particles collide with enough energy to break into charged particles (+/-)2.) gas-like, indefinite shape & volume3.) stars, fluorescent light bulbs, TV tubes

Thermal Expansion

Most matter expands when heated & contracts when cooled.

Temp causes KE. Particles collide with more force & spread out.

Let’s Re-Visit The Kinetic Molecular Theory

We make several assumptions when we talk about the kinetic molecular theory for gases:

Particle Size: Gases are composed of mostly empty space, which means the volume of the particles is small compared to the volume of the empty space.

Particle Motion: Gases are in constant, random motion. Gases have elastic collisions which means they loose NO kinetic energy when the bump into each other.

Particle Energy: KE = 1/2mv2 Temperature is a measure of the average kinetic energy of the particles in a sample of matter.

Gases

Gases are Expandable and Compressible!

Gases have Low Densities! Density is

mass per unit volume.

Gases can diffuse and effuse which describes the movement of one material through another!

• Think Perfume

area

forcepressure

Pressure

Which shoes create the most pressure?

Key Units at Sea Level:

101.325 kPa (kilopascal)

1 atm

760 mm Hg

14.7 psi

Pressure

The pressure gases exert comes from them hitting the sides of the container they are in.

Barometer

Atm

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Pre

ssur

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Manometer

Cont

aine

d Pr

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Pressure

Dalton’s Law of Partial Pressures

Dalton’s Law of Partial Pressures states that each gas present in a mixture exhibits its own individual

pressure so that the sum of the total mixture of gases is equal to the sum of the individual pressures.

PT = P1 + P2 + P3 + …..

Let’s Try an Example Problem …

A mixture of oxygen, carbon dioxide, and nitrogen has a total pressure of 0.97atm. What is the partial pressure of O2, if the partial pressure of CO2 is 0.70atm and the partial pressure of N2 is 0.12atm?

Let Me Pose a Question …..

If all particles of matter at room temperature have the same kinetic energy, why then do we see some substances as solids, some as liquids,

and some as gases?

The attractions between molecules are not nearly as strong as the

intramolecular attractions that hold compounds together.

Intramolecular

Intermolecular Forces

It’s all about strength!!!

The stronger the force … the stronger the bond …

and the stronger the bond … the more

closely together the molecules will be

packed … the closer they are packed, the

more likely you are to be a solid.

London Dispersion Forces

Dispersion Forces are weak forces that result from temporary shifts in the density of

electrons in electron clouds.

Dipole- Dipole Interactions

Molecules that have permanent dipoles areattracted to each other. * The positive end of one is attracted to the negative end of the other and vice versa. * These forces are only important when the molecules are close toeach other.

Hydrogen Bonding

The dipole-dipole interactions experienced when H is bonded to N, O, or F are unusually strong.

* We call these interactions hydrogen bonds.

Hydrogen Bonding

Hydrogen bondingarises in part from

the high electronegativity

of nitrogen, oxygen,and fluorine.

Also, when hydrogen is bonded to one of those very electronegative elements, the hydrogen nucleus is

exposed.

Name That Bond!

Please Name the Intermolecular Force at work amongst the following molecules…

H2

NH3

HClHF

Dispersion Forces

Hydrogen Bonding

Dipole- Dipole

Hydrogen Bonding

Intermolecular Forces AffectMany Physical Properties

The strength of the attractions

between particles can greatly affect

the properties of a substance or

solution.

ViscosityResistance of a liquid to

flow is called viscosity.It is related to the ease

with which molecules can move past each other.

Viscosity increases with stronger intermolecular forces and decreases with higher temperature.

Surface TensionSurface tension results from

the net inward force experienced by the

molecules on the surface of a liquid.

Energy’s Role• Officially- energy is the ability to do

work, but you can also think of it as the ability to change or move matter.

Think about it … matter is made of atoms … and the

state the matter is in depends on how fast the particles are moving … so energy and the state of

matter are directly related. So, how does

matter change its state?

Thermal Energy

The total kinetic energy of the particles that make up an object.

High Kinetic Energy = High Thermal Energy

Note! Thermal energy also

depends on the amount of

substance …

Temperature

Temperature is simply a measurement of a substance’s average kinetic energy!!

We usually think of temperature as a measure of how hot or cold something is … can you come up with a different definition???

Changes of State

When matter changes the state it’s in … this is an example of a physical change!

Since the state of matter is directly related the amount of energy it has … then for the state to change- it stands to reason that the energy must change as well.

Changes of State

Sublimation

Melting

Freezing

Condensation

Evaporation

Some changes of state require energy to happen … while other require the removal of energy.

Phase Changes

Phase Change Diagram