kinetic theory (a)

Kinetic TheorySolids, liquids and gases

States of matterRemember, all substances are made

up of tiny particles that are moving.The arrangement of these particles

and the way that they are moving determine the properties of the material.

The states of matter are:◦Solid◦Liquid◦Gas

SolidsFixed shape.Fixed volume.High density.Will not flow.Particles in a solid vibrate about

a fixed position. The more energy, (heat) in the solid, the faster these particles vibrate.

LiquidsNo fixed shape.Fixed volume.Less dense than solids.Will flow.Particles in a liquid can move

more freely around each other. As the liquids is heated, the movement becomes more energetic.

No fixed shape.No fixed volume.Very low density, (allows them to

be compressed).Will flow.Particles of gas are moving

around randomly all the time. Collisions between the particles and their container causes pressure.

Gases

Changes of state

Solid Liquid Gas

Melting Evaporation

Freezing Condensation

Sublimation

Changes of stateAs we heat solids the particles

start to vibrate more – they gain kinetic energy.

We notice the increase in kinetic energy of the particles as an increase in temperature.

If the particles are moving rapidly enough, then the solid will melt.

Changes of stateAs we heat liquids the movement

of the particles becomes even more energetic.

If the particles move fast enough then they can break the attractive forces between the particles and move independently.

The liquid evaporates to form a gas.

Brownian motionNamed after the botanist

Robert Brown (1773-1858).

Observed pollen grains moving randomly in water.

Thought it might be due to a “life force” in the pollen.

However, also observed the movement in non-living particles.

Similar effect can be seen in gases.

Brownian motionBrownian motion was not

explained until Particle Theory was developed.

Particles in liquids and gases are constantly moving and bump into other particles, such as pollen grains.

This causes the random movements of the grain that was observed.

A good example is the movement of smoke particles in air.

Brownian motion

Kinetic TheoryWhat can you remember?

States of matterRemember, all substances are made

up of tiny particles that are moving.The arrangement of these particles

and the way that they are moving determine the properties of the material.

The states of matter are:◦Solid◦Liquid◦Gas

substancesparticlesarrangement

moving

Solid

LiquidGas

SolidsFixed shape.FixedHigh density.Will not flow.Particles in a solid vibrate about

a fixed position. The more energy, (heat) in the solid, the faster these particles vibrate.

shape.volume.density.

flow.vibrate

position. heatfaster

LiquidsNo fixed shape.Fixed volume.Less dense than solids.Will flow.Particles in a liquid can move

more freely around each other. As the liquids is heated, the movement becomes more energetic.

shape.volume.dense solids.flow.

freely

heated,energetic.

No fixed shape.No fixed volume.Very low density, (allows them to

be compressed).Will flow.Particles of gas are moving

around randomly all the time. Collisions between the particles and their container causes pressure.

Gases

shape.volume.density,

compressedflow.

randomly Collisions

pressure.

Changes of state

Solid Liquid Gas

Melting Evaporation

Freezing Condensation

Sublimation

Changes of stateAs we heat solids the particles

start to vibrate more – they gain kinetic energy.

We notice the increase in kinetic energy of the particles as an increase in temperature.

If the particles are moving rapidly enough, then the solid will melt.

heatvibrate kinetic

energy

temperature.particles

melt.

Changes of stateAs we heat liquids the movement

of the particles becomes even more energetic.

If the particles move fast enough then they can break the attractive forces between the particles and move independently.

The liquid evaporates to form a gas.

heat movementenergetic.

particlesattractive

independently.evaporates gas.

Brownian motionNamed after the botanist

Robert Brown (1773-1858).

Observed pollen grains moving randomly in water.

Thought it might be due to a “life force” in the pollen.

However, also observed the movement in non-living particles.

Similar effect can be seen in gases.

Robert Brown

pollen randomly

“life force”

non-livinggases.

Brownian motionBrownian motion was not

explained until Particle Theory was developed.

Particles in liquids and gases are constantly moving and bump into other particles, such as pollen grains.

This causes the random movements of the grain that was observed.

A good example is the movement of smoke particles in air.

Particle Theory

movingparticles,

random

smoke particles

Brownian motion