Kinetic Particle Model of Matter 

States of Matter: 

Matter exists mainly in three states: solid, liquid, and gas.

Solids:

• Particles are packed closely in fixed positions.

• Vibrate about fixed points only.

• High density.

• Fixed shape and volume.

• Incompressible.

Liquids:

• Particles are close but not fixed.

• Slide over each other with some freedom.

• Moderate density.

• No fixed shape (take container shape).

• Fixed volume but not fixed shape.

Gases:

• Particles are far apart and randomly arranged.

• Move freely and rapidly in all directions.

• Low density.

• No fixed shape or volume.

• Easily compressible.

Example Questions:

• Explain why solids cannot be compressed but gases can.

• Why do liquids take the shape of their container while solids do not?

Changes of State Matter changes from one state to another when energy is absorbed or released.

• Melting: solid → liquid

• Freezing: liquid → solid

• Evaporation: liquid → gas (at surface, below boiling point)

• Boiling: liquid → gas (throughout liquid, at boiling point)

• Condensation: gas → liquid

• Sublimation: solid ↔ gas directly

Melting Point: temperature at which a solid changes to a liquid.

 Boiling Point: temperature at which a liquid changes to a gas.

 Latent Heat: energy absorbed or released during a change of state without temperature change.

Example Questions:

• State two differences between evaporation and boiling.

• Why does temperature remain constant during melting?

Kinetic Particle Theory:

 This theory explains the properties of solids, liquids, and gases in terms of particle movement. Higher temperature means higher kinetic energy.

Absolute Zero:

 Absolute zero (0 K or -273°C) is the temperature at which particles have minimum energy and stop moving.

Temperature, Pressure, and Particle Motion:

• Higher temperature → faster particle movement → more frequent and forceful collisions → higher pressure.

• Decreasing volume at constant temperature increases pressure.

Gas Law: p × V = constant (for a fixed mass of gas at constant temperature)

Brownian Motion:

 Brownian motion is the random zigzag movement of small particles caused by collisions with faster-moving molecules.

Example Questions:

• How does Brownian motion support the existence of molecules?

• Describe an experiment to observe Brownian motion.

Collision Theory:

 Gas pressure results from collisions of gas particles with container walls.

• Higher temperature → greater energy of particles.

• Lower volume → more frequent collisions.

Conversion Between Celsius and Kelvin 

T(K) = T(°C) + 273

Example Questions:

• Explain why the pressure of a fixed mass of gas increases when volume decreases.

• Convert 20°C into Kelvin.

• A gas at 300 K has a volume of 2.0 m³. Find its volume at 600 K (pressure constant).

End of Notes – Kinetic Particle Model of Matter 

Made by Hiba Shakeel 

Curated by Yassein Abdoun