Kinetic Model Of Matter.

• Matter is made up of particles.
• At room temperature, matter exists either as a solid, a liquid or a gas.
• The particles in a matter arrange and behave differently in a different physical states.


Properties of solids, liquids and gases.

Solid
• Fixed shape
• Fixed volume
• High density
• Incompressible

Liquid
• Does not have a fixed shape
• Fixed volume
• High density
• Incompressible

Gas
• No fixed shape
• No fixed volume
• Low density
• Compressible

>States On Matter, Video- YouTube

Kinetic model of particles in matter.

Molecular Structure:

Solid
- Motion: Molecules and atoms vibrate at fixed positions only
- Attractive Force: Very strong intermolecular bonds
• Show that solids have fixed volume and shape.

- Arrangement: Regular and fixed
- Distance: Very close together, occupying minimum space
• Results in solids having high densities.


Liquid
- Motion: Molecules and atoms move about within confined space
- Attractive Force: Moderate, found between particles

- Arrangement: Irregular and random
- Distance: Quite close
• Results in liquids having relatively high densities .


Gas
- Motion: Molecules and atoms move freely in all directions at high speed
- Attractive Force: Very weak, have very little attraction between particles
• Show that gases are highly compressible and that they have no fixed volume and shape.

- Arrangement: Irregular and random
- Distance: Very far apart
• Results in gases having very low densities.

>Eureka! Episode 16 - Molecules in Solids, Video-YouTube

>Eureka! Episode 17 - Molecules in Liquid, Video-YouTube



Use of kinetic model of particles.

Solids have higher melting points and boiling points that liquids and gases.
• The attractive force between the solid particles is very strong, so it requires more energy to break down the force between them.

Why can gases be compressed but not solids and liquids?
• Solids and liquids cannot be compressed because the particles are closely packed and there is very little empty space between them. Particles of a gas are far apart and there are lots of empty spaces between them, so they can be compressed.

Why does liquid have a definite volume but not a fixed shape?
• Particles in a liquid are held by strong attractive forces and are closely packed, so it has a fixed volume. The particles are not orderly, so the liquid can take the shape of the container.




Brownian motion

-Random or irregular motion of smoke particle
-Occurs only in fluids (liquid and gas)


Effects of temperature on molecular motion.
- The Higher the temperature, the more vigorous and agitated the smoke particles move.
- The Lower the temperature, the motion of particles will be less agitated.

• This is because as temperature increase, a larger amount of thermal energy is converted to kinetic energy of the air molecules, causing the molecules to move faster.