2.1.1
Molecular Kinetic Theory Model
Brownian Motion
Brownian Motion
Brownian motion was the first direct evidence of atoms.


Robert Brown
Robert Brown
- Robert Brown noticed that tiny pollen grains suspended in still water moved about in random paths.
- The pollen would change direction without colliding with other pollen grains.
- This can be observed with a microscope for any small particles in a fluid.
 _Diagram - 1.1.6_ Random bombardment of particles ,h_400,q_80,w_640.png)
 _Diagram - 1.1.6_ Random bombardment of particles ,h_400,q_80,w_640.png)
Atoms
Atoms
- The random motion of the pollen grains is caused by atoms randomly colliding with pollen in the fluid.
- This is direct evidence of atoms existing.
Pressure of an Ideal Gas
Pressure of an Ideal Gas
The pressure of an ideal gas is closely related to the temperature and volume.


Pressure
Pressure
- The pressure from a gas comes from molecules colliding with the wall of a container.
- Pressure can be increased by:
- Increasing concentration - collisions between molecules are more frequent if the molecules are packed together more tightly.
- Increasing temperature - hot gases have more kinetic energy and so more collisions will happen.
- Decreasing container size - this will increase the number of collisions.


Temperature and volume
Temperature and volume
- Pressure is linked to temperature and volume.
- Consider pumping up an empty car tire.
- Initially, the temperature will remain the same as the volume increases from a small increase in pressure.
- Next, the pressure will increase a lot as the volume refuses to expand more.
- Finally, the temperature will increase as the car is driven, this will increase the pressure.
1Space, Time & Motion
1.1Motion
1.2Forces
1.3Momentum & Impulse
2The Particulate Nature of Matter
2.1Thermal Concepts
3Wave Behaviour
3.1Oscillations
3.2Travelling Waves
3.3Wave Characteristics
3.4Wave Behaviour
3.5Standing Waves
3.6Simple Harmonic Motion
3.7Single Slit Diffraction
3.8Interference
3.9Doppler Effect
4Fields
4.1Circular Motion
4.2Newton's Law of Gravitation
4.3Fields
4.4Fields at Work
4.5Electric Fields
4.6Magnetic Effect of Electric Currents
4.7Heating Effect of Currents
4.8Electromagnetic Induction
4.9Power Generation & Transmission
5Nuclear & Quantum Physics
5.1Discrete Energy & Radioactivity
5.2Nuclear Reactions
5.3The Interaction of Matter with Radiation
6Measurements
6.1Measurements & Errors
6.2Uncertainties & Errors
6.3Vectors & Scalars
Jump to other topics
1Space, Time & Motion
1.1Motion
1.2Forces
1.3Momentum & Impulse
2The Particulate Nature of Matter
2.1Thermal Concepts
3Wave Behaviour
3.1Oscillations
3.2Travelling Waves
3.3Wave Characteristics
3.4Wave Behaviour
3.5Standing Waves
3.6Simple Harmonic Motion
3.7Single Slit Diffraction
3.8Interference
3.9Doppler Effect
4Fields
4.1Circular Motion
4.2Newton's Law of Gravitation
4.3Fields
4.4Fields at Work
4.5Electric Fields
4.6Magnetic Effect of Electric Currents
4.7Heating Effect of Currents
4.8Electromagnetic Induction
4.9Power Generation & Transmission
5Nuclear & Quantum Physics
5.1Discrete Energy & Radioactivity
5.2Nuclear Reactions
5.3The Interaction of Matter with Radiation
6Measurements
6.1Measurements & Errors
6.2Uncertainties & Errors
6.3Vectors & Scalars
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