Chemistry IGCSE - States of matter

Solid

• definite volume and shape

• incompressible

Liquid

• definite volume

• no definite shape

• slightly compressible

Gas

• no definite shape nor volume

structure of solids in terms of particle separation, arrangement and motion

• packed tightly together

• regular arrangement

• vibrate in fixed position

structure of liquids in terms of particle separation, arrangement and motion

• arranged randomly

• close together, touching close particles

• random vibration

structure of gases in terms of particle separation, arrangement and motion

• far apart with no regular arrangement

• separate far apart

• move randomly quickly

Changes of state in terms of melting, boiling, evaporating, freezing and condensing

Melting: solid → liquid

Evaporating: liquid → gas

Freezing: solid → gas

Condensing: liquid → solid

Describe the effects of temperature and pressure on the volume of a gas

increase in temperature → increase in kinetic energy of particles → more forceful collisions against container wall → increase in pressure → the walls can expand → gas volume increases

kinetic particle theory

all matter is composed of tiny particles which are in random movements through space that exists between them

Explain changes of state in terms of kinetic particle theory

decrease in kinetic energy → movements decrease → goes from liquid to solid

increase in kinetic energy → movements of particles increase → goes from solid to liquid

Heating curves

temperature of substance increase with kinetic energy → solid to gas

Cooling curves

temperature of substance decreases with kinetic energy → gas to solid

Describe and explain diffusion in terms of kinetic particle theory

diffusion → random movement of particles from high to low concentration

Describe and explain the effect of relative molecular mass on the rate of diffusion of gases

Molecules with lighter masses → diffuses faster

Molecules with heavier masses → diffuses slower