Chapter 08 Part 1Chapter 08 Part 1Kinetic Model Of Matter

What is the smallest building What is the smallest building block of matter?block of matter?For this course, the

smallest building block is◦an atom(element)◦a

molecule(compound)

What is this model?What is this model?

The Kinetic Model of Matter states that:

matter are composed of a large number of small particles (i.e. atoms, molecules)

individual particles are in constant motion.

3 states of matter3 states of matterSolid

◦Fixed shape and volume◦Normally hard & rigid; a large force

is needed to change its shape◦High density◦Incompressible

3 states of matter3 states of matterLiquid

◦Fixed volume but does not have a fixed shape

◦High density◦Incompressible

3 states of matter3 states of matterGas

◦No fixed shape or volume◦Low density◦Compressible

3 states of matter with the 3 states of matter with the kinetic model of matter kinetic model of matter gives…gives…The kinetic model of matter

3 states of matter explained 3 states of matter explained using the kinetic model of using the kinetic model of matter: matter: SolidSolid

Arrangement of particles◦ Closely packed

together◦ Usually in a

regular pattern◦ Occupying

minimum space◦ Results in solids

having high densities

Movement of particles◦ Vibrate about fixed

positions only.◦ Held by very strong

intermolecular bonds.

◦ This explains why solids have fixed volumes and shapes.

3 states of matter explained 3 states of matter explained using the kinetic model of using the kinetic model of matter: matter: LiquidLiquid

Arrangement of particles◦ Randomly arranged◦ Particles are

slightly further apart as compared to solids

◦ Results in liquids having relatively high densities (generally less dense than solids)

Movement of particles◦ Free to move about

but confined within the vessel containing it.

◦ Have attractive forces between particles.

◦ This explains why liquids have fixed volumes but will take the shape of the vessels containing them.

3 states of matter explained 3 states of matter explained using the kinetic model of using the kinetic model of matter: matter: GasGasArrangement

of particles◦ Randomly

arranged◦ Particles are very

far apart◦ Occupy any

available space.◦ Results in gases

having very low densities

Movement of particles◦ Move about

randomly, freely and at high speeds

◦ Have very little attractive forces between particles.

◦ This explains why gases have no fixed volume and shape, and why they are highly compressible.

3 states of matter explained 3 states of matter explained using the kinetic model of using the kinetic model of mattermatter

Evidence to support the Evidence to support the kinetic model of matterkinetic model of matterThe size of atoms/molecules are

very small.Nobody has ever seen an atom or

a molecule before.How do we know that the kinetic

model of matter is correct?◦The observation of Brownian motion

Brownian motionBrownian motionThe random or irregular motion of microscopic particles suspended in fluids due to the uneven bombardment of the suspended particles by the molecules of the fluid is called Brownian motion.◦Occurs only in fluids.

The setup to observed The setup to observed Brownian motionBrownian motion

Why do the smoke particles Why do the smoke particles move irregularly and move irregularly and haphazardly?haphazardly?The smoke particles, being

much larger than the air molecules, are continually bombarded unevenly from different sides by the surrounding air molecules.

Smoke particle

Air molecule

Effects of temperature on Effects of temperature on molecular motionmolecular motionThe Brownian motion of smoke

particles at higher temperature will be more vigorous and agitated.

Why??◦As temperature increases, a larger

amount of thermal energy is converted to kinetic energy of the air molecules.

◦Causes the air molecules to move at higher speeds.

◦Thus, the air molecules will bombard the smoke particles more vigorously and frequently.

◦Causing the Brownian motion of the smoke particles to be more vigorous and agitated.