C1_states, p&s changes + particles

C1_states, p&s changes + particles

1. physical & chemical changes

   • physical = a change when a substance changes ate shape or breaks
     • e.g. heating
       • How do you know its a physical change?
         • ~ The opposite of all the chemical changes.
         • ~ it is reversible
         • ~ It can be separated.
   • chemical = a change that produces one or more new substances.
     • eg. burning
       • How do you know its a chemical change?
         • ~ The colour of the product will change.
         • ~ Bubbles of gas appear
         • ~ The temperature changes.
         • ~There's light given offf

2. solid, liquid and gas.

   • solid
     • has a definite shape
     • has a definite volume
     • cannot be compressed
     • it cant flow.
     • the particles have a fixed shape, and pattern
     • they can only vibrate.
   • liquid.
     • it cant be squashed
     • it can flow
     • it doesn't have a definite shape
     • its volume is definite
     • the particles are arranged randomly
     • liquid particles touch each other
   • gas.
     • no definite shape
     • no fixed volume
     • takes the shape of a container
     • can be compressed
     • particles are randomly arranged
     • move around freely
     • large spaces in-between particles

3. limitations of particle model.

   • doesn't account for........
     • the size of the particles
     • the electro-static forces between the particles
     • the distance between the paricles
       • How do you work out the ratio of the distance between the particles.
         • distance/diameter
           • *you will be given the distance and diameter
             • e.g. 3.4x10-9/0.2x10-11=0.55x10^2
               • remember, the diameter is double the radius.