C15 Kinetic Particle Theory

Solid shape

Fixed unless acted on by force

Liquid shape

Take shape of container, can be pourd

Gas shape

Fills container, can be poured, will escape if open

Solid compressibility

Cannot be compressed

Liquid compressibility

Cannot be compressed

Gas compressibility

Easily compressed

Solid rate of diffusion

Does not diffuse

Liquid rate of diffusion

Slow

Gas rate of diffusion

Quick

Solid density

Relatively high

Liquid density

Relatively high

Gas density

Very low

In kinetic theory, all substances are made up of

Particles (atoms, ions, molecules)

In kinetic theory, kinetic energy of particles increases with

Temperatre

In kinetic theory, all particles are… to each other (with varying strengths)

Attracted

In kinetic theory, all particles have…

Kinetic energy

Particles in solid vibrations

Vibrate about fixed position

Particles in crystalline solid

Regular arrangement

Particles in liquid

Can slide past one another

Arrangement of particles in liquid regular/irregular

Irregular

Movement of particles in gas

Very quick, straight lines between collisions

Arrangement of particles in gas

Far apart

What holds particles in solid substance in fixed positions

Attractive forces between particles

How is energy passed between particles

Collisions

What causes solid substance to expand when heated

More vigorous vibrations cause particles to separate slightly

What happens at melting point of substance

Particles overcome some of attractive forces - now able to slide

Why does temperature not rise during melting

Energy supplied is being used to overcome attractive forces

When will the temperature of liquid rise after hitting melting point

Once whole substance has melted

What is evaporation from liquid

Surface particles have enough E (from collisions) to overcome attractive forces and become gas

What temperature does evaporation happen at

Below boiling point of substance

What happens at boiling point of substance

Particles gain enough e to overcome forces of attraction, escape as gas

Does temperature rise during boiling

No

Do the same changes in temperature + changing state occur when cooling

Yes

Why does temperature not drop when gas is condensing

Energy is released as new attractive interactions form

Do state changes of substance change at different pressures

Yes

Forces of attraction between particles in simple molecular substance

Weak intermolecular forces

Melting and boiling points of simple molecular substances

Low

Do larger molecules generally have stronger intermolecular forces

Yes

How does branching in alkanes affect intermolecular forces

Branching weakens intermolecular forces

How do branched molecules melting/boiling points compare to straight chain molecules (with same Mr)

Lower

Why do covalent bonds have very high melting and boiling points

Strong covalent bonds need to be overcome

Why do metals have high melting and boiling points usually

Giant structure - usually many strong attractions between nuclei and delocalised electrons

Forces of attraction in metals are between

Nuclei and delocalised electrons

Do metal compounds have giant structure

Yes

Do ionic compounds have a giant structure

Yes

Do ionic compounds have high melting and boiling points

Yes

Forces of attraction in ionic compounds

Strong electrostatic forces acting in all directions around ion