In solids, particles are: closely, regularly packed, only movement is slight vibration.
In liquids, the particles are: mainly touching, with some gaps, less dense than solids due to this, force of attraction between the particles is less than in solids, particles can move
In gas, the particles are: further apart, almost no force of attraction, big space between the particles.
Ice floats on water, because solid water (ice) is less dense than liquid water, this is very unusual, thus less dense thing floats because it is lighter.
Changing State:
When heating a solid, the thermal energy will make the solids particles vibrate faster and faster, until they virbrate fast enough, that the force of attraction between the particles is no longer strong enough to hold them together. The solid melts to a liquid. The temperature required to melt the solids is its MELTING POINT.
From Solid to a liquid = Melting. From Liquid to a solid = Freezing, From liquid to a gas = Boilding/(evaporating). From Gas to a liquid = Condensing. and from a solid to a gas or gas to solid = sublimation.

Particles diffuse down a concentration gradient, from an area of high concentration to an area of low concentration. = Diffusion (in gases and for particles dissolved in solutions)

Diffusion in liquids is very slow as the gaps between the particles is not very big.

	Created by Sophia t about 10 years ago

Revision of chemistry topics for january mock exam from the text book edexel international gcse chemistry. edexel certificate in chemistry