Arrangement and movement of molecules
Dynamic Equlibrium
In the diffusion of substances the particles at first will move from the area of low concentration to high concentration.
Then as the concentration of the substance increases more molecules will move around to find the area of lowest concentation
Eventually, as one molecule moves to another area one other molecule will move to the area the first molecule came from. This is when a Dynamic Equilibrium is reached and the reaction stops.
Random movement of molecules in liquids, solids and gases
Behaviour of molecules
In all states of matter; liquid, solid and gas, if the temperature is increased, the particles gain more kinetic energy and vibrate and move more quickly.
The particles in solids, liquids and gases the are above absolute zero will all move in the same sort of way. at absolute zero the movement of particles will stop
Liquids
Particles in a liquid move randomly and can slide past each other but they don't move far away from each other.
Particles in liquids are close together, rolling over each other and arranged randomly.
Solids
Particles in a solid vibrate in all directions but cannot move out of their fixed positions.
Particles in solids are touching each other and in fixed positions
Observing Brownian motion led to the development of the kinetic model of matter
Brownian motion can be observed under a microscope looking at illuminated smoke particles.
This was the first evidence to show that molecules in gases and liquids are constantly moving.
Albert Einstein then theorised that the pollen grains were moving constantly because they were being bombarded by much smaller water molecules.
He observed pollen grains in water under a microscope. He noticed that the pollen grain moved around jerkily in a random fashion.
Brownian motion was developed by Robert Brown
Gases
Particles in a gas move quickly and travel large distances in all directions. the molecules constantly hit each other and the wall of whatever container they are in. This causes them to change direction.
Particles in gases are far apart and arranged randomly