Zusammenfassung der Ressource
1st half term grade test
- Particle theory
- States of matter
- Solid
Anmerkungen:
- Particles are close together in a regular arrangement
- The attraction between particles are strong.
- The particles vibrate around a fixed position; a solid has a fixed shape.
- The volume does not change because the particles cannot move closer together.
- Liquid
Anmerkungen:
- Particles are still close together (most touching) but are arranged irregularly
- The force of attraction between particles is less strong than a solid.
- The particles move around and slide past each other; liquids can be poured.
- Under pressure the volume does not change because the particles cannot move closer together.
- Gas
Anmerkungen:
- Particles are far apart, arrangement is random.
- The force of attraction between particles is very weak.
- The particles move freely and at speed, they collide with each other and bounce away randomly; gasses spread.
- Under pressure the gas is pushed into a smaller volume because the particles can move a lot closer together.
- Diffusion
Anmerkungen:
- Difussion is where particles mix and spread throughout the space, evening the concentration out until they are the same.
- Speed of diffusion
Anmerkungen:
- The smaller the relative molecular mass, the more quickly particles diffuse.
- Diffusion is also faster when -
A. It is hotter, the particles move faster as they have more energy
B. It is in gas as the speed of gas particles is faster.
- Changing state
Anmerkungen:
- On heating particles gain energy and move faster; they change state when they gain enough energy to overcome the forces of attraction.
- On cooling, the particles lose energy and move more slowly; as they get closer the forces of attraction take over and change state.
- Cooling and heating curves
Anmerkungen:
- When a substance is pure then the temp remains the same during a change of state (I.e. horizontal part of graph)
- During boiling the energy breaks these attractions futher
- During melting the energy- heat, is being used to break some of the attractions between particles.
- In between state changes the particles are vibrating and moving more as the energy is taken in and the temp rises.
- Heating curve
- Cooling curve
- Purity
Anmerkungen:
- By measuring the melting and boiling points you can tell if pure.
You can identify pure substance by measuring melting and boiling point.
- Pure
Anmerkungen:
- Has no particles of any other substance mixed in with it.
Melts and boils at unique temp.
Melts sharply at melting pt
- Impure
Anmerkungen:
- Has other particles mixed in
Melts over range temp not sharply.
Melt lower temp
Boil higher temp
- Definitions
- Element
Anmerkungen:
- Pure substance containing only one type of atom e.g. oxygen
- Compound
Anmerkungen:
- A pure substance containing 2 or more types of atom chemically bondede.g. CH4
- Mixture
Anmerkungen:
- 2 or more substances which are not chemically bonded and can easily be seperated by phisical process. E.g. air