10. Kinetic Particle Model of Matter Flashcards
Kinetic Particle Model of Matter
states that…
All matter is made up of numerous tiny particles which are in continuous motion.
Solid
Arrangement (& distance) + Motion (& attraction) + Observable Properties
Arrangement:
- Particles are closely packed and arranged in a regular pattern.
- Particles have the least energy among the 3 states of matter.
Motion:
- Particles vibrate about fixed positions.
- They are held in position by strong attractive forces between particles.
Observable properties:
- Solids have the highest densities.
- Solids have a fixed volume and fixed shape.
Liquid
Arrangement (& distance) + Motion (& attraction) + Observable Properties
Arrangement:
- Particles are slightly less closely packed than in solids and arranged in an irregular pattern.
Motion:
- Particles slide over each other throughout the liquid without fixed positions.
- The forces holding the particles together are weaker than in a solid.
Observable properties:
- Liquids have slightly lower density than solids.
- Liquids have a fixed volume and no fixed shape.
Gas
Arrangement (& distance) + Motion (& attraction) + Observable Properties
Arrangement:
- Particles are very far apart from one another in an irregular pattern.
- The particles in gases have the most energy among the 3 states of matter.
Motion:
- The particles can move freely in any direction.
- The attractive forces between particles are weak.
Observable properties:
- Gases have the lowest densities.
- Gases have no fixed volume (can be compressed) and no fixed shape.
- A gas takes up the volume and shape of its container.
Brownian motion
What it is + Observations + Explanation and How it is caused
Brownian motion refers to the continuous, random motion of particles suspended in a liquid or gas, as a result of bombardment by fast moving liquid or gas particles.
Observation:
- The smoke particles move about in a continuous, random manner.
- The larger the smoke particles, the less agitated the motion.
Explanation:
- Random motion is due to the constant, uneven bombardment of the smoke particles by the invisible air particles.
To cause Brownian motion of the smoke particles, air particles must be moving continuously, in random directions and at high speeds when they collide with the smoke particles.
Effect of temperature on observed Brownian motion
- Temperature of air increases
- Average kinetic energy/speed of air molecules increases
- Air molecules bombard smoke particles more forcefully and frequently
- Smoke particles move at a higher average speed and change direction more frequently
How do gas particles inside a sealed container produce a pressure on the container’s inner walls?
Gas particles inside the container are in constant and random motion.
When the gas particles collide with the inner wall, they exert a force on the wall.
The force per unit area gives rise to the pressure exerted by the particles on the wall.
Effect on pressure when volume increases at constant temperature
At constant temperature, when the volume increases, the particles will collide with the walls less frequently.
Hence, pressure of the gas decreases.
Effect on pressure when temperature increases at constant volume
At constant volume, when the temperature increases, the average speed of the particles increases, so the particles will collide with the walls of the container more frequently and more forcefully.
Hence, pressure of gas increases.
Effect on pressure when temperature increases in a container which can change volume
In a container with a piston that is free to move, when the temperature increases, the piston will move outwards, and volume increases. The particles will collide with the walls of the container less frequently but more forcefully (as the average speed of the particles increases).
Hence, pressure of gas remains constant.
