Particle Model: solids, liquids and gases

Particle Model: solids, liquids and gases

1. Random movement of particles is called Brownian motion

   • Random movement of particles. We call this diffusion
   • Movement of particles produces a pushing force or pressure on a surface.

2. 1. All matter is made up of particles

   • 2. The particles can be of different sizes.
     • 3. The particles move around by themselves in a random way.
       • 4. The particles attract each other
         • 5. The hotter the substance the faster the particles move.
           • Some scientists call this model the kinetic theory.

3. We often describe matter or materials as substances

4. Substances can be sorted into three groups: solids, liquids and gases. These three groups are called the three states of matter.

   • Solids don't flow because the forces between the particles are strong. Gases and liquids flow because the forces between particles are much weaker
   • Expansion means geting bigger. Solids expand slighty; liquids expand more and gases expand a great deal. During expansion the particles move further apart. The particles don't get bigger.
   • Solids and liquids are difficult to compresses, but gases compress easily. This is because gases have large gaps between the particles.
     • In a gas, there is little attraction between the particles so they move freely. the particles are far apart and moving very fast.
     • In liquids, the particles are still attracted to each other but they move faster. They swap places with each other. There is a little more space between the particles.
     • In solids, strong forces hold the particles together so they vibrate, but do not not change places. there is little space between the particles.