C1

Solids, liquids and gases
- Solid:
  - Definite volume & shape
    - Affected by change in temperature
      - Heated: size increase slightly (expanision)
      - Cooled: size decreases (contraction)
    - Liquid:
      - Fixed volume
      - Takes shape of container
      - Volume: slightly affected by temperature
    - Gas:
      - No definite shape & volume
      - Takes shape of conatiner
      - Spreads out evenly
      - Change in temperature: affects volume a lot
    - Liquids & gases: compressible
      - Volume reduced with pressure
      - Gas > liquid
Kinetic theory of matter
- Explains way matter behaves
  - Physical properties: movements of particles
  - How arrangement of particles relates to properties of states of matter
- Points of theory
  - All matter: made of moving particles
    - Different substances à different particles (atoms, molecules, ions) vary in size
  - Particles always move
    - Higher temperature: move faster
  - Heavy particles: move slower

Explaining states of matter

- Solid: partciles attract to one another
  - Attractive forces between particles -> holds them together
  - Particles: little freedom to move
  - Vibrate in fixed position
  - Arranged in regular manner
- Liquid
  - Partciles: close together
    - Can move randomly -> often collide
  - Attraction forces: weaker than in solid
  - Particles: more energy than in solid
- Gas
  - Partciles: far apart
  - Free to move in container
  - Move randomly with high velocity
    - Faster than liquids
    - Collide but not often with one another & wall
  - Exert no forces of attraction
- Pressure in balloon
  - Cause: gas particles striking inside of balloon
  - High temperature: more pressure
    - Particles: more energy -> move faster -> hit surface more often
  - Balloon stretches & volume increases
Changes of state
- Solids
  - Melting prcoess
    - Heated
    - Particles vibrate faster
    - Gain energy
    - ‘push’ neighbouring particles away
    - Increases volume
    - Expands
    - Attraction forces: weaken
    - Regular structure pattern: breaks down
    - Particles can move around each other
  - Melting point: temperature at which solid melts
  - Temperature of pure melted solid: does not change until melted
  - Still attraction forces -> not gas
  - Solids with higher malting point: stronger forces of attraction
- Liquid
  - Evaporation process
    - Heated
    - Parcticles move faster
    - Energy increases
    - Particles on suface have enough energy to overcome forces of attraction
    - Escape to form gas
    - Liquid evaporates
  - Boiling point: temperature particles try leave liquid so fast -> bubbles form
    - Pressure of gas created abov eliquid: atmospheric pressure
  - Liquids with high boiling point: stronger forces of attraction
  - Freezing: liquid cooled
- Gas
  - Condensation processes
    - Gas: cooledtHEst
    - Energy decreases
    - Particles move closer together
    - Forces of attraction increase
  - Change of state: physical change
    - Temperature stays constant during change
    - No new substance is formed

Heating & cooling curves

- Ice: water particles = close together
  - Atrracted to one another
  - Melt: need enough energy to overcome forces of attraction between particles & oallow relative movement
- Temperature rises after all of ice is melted
- Heating curve for solid: stops rising at melting point & gives rise to sharp melting point
- Sharp melting point: indicated pure sample
- Impurities lower melting point
- Solids & liquids: identified by melting & bioling point
Diffusion - evidence for moving particles
- Diffusion: spreading out gas
  - In haphazard & random way
- All gases diffure to fill space
- Diffuse at different rates
- Gas with lower R.A.M -> move faster
- Liquids also diffuse
  - Slower
- Intimate mixing
  - Diffusion between liquid & gas
  - Collisions = random between particles in liquid or gas -> enough space between particles of one substance for particles of other substance to move into
Atoms, molecules and ions
- 1803 John Dalton: element made of particles (atoms)
- Atoms:
  - 20 x 10atoms = 1cm

- - Smallest atom: hydrogen
  - Atoms from different elements = different diameters & masses
- Molecules
  - Atoms of some elements: joined together in small groups
    - Same or different
  - Diatomic molecules: pairs
- Ions
  - Small particle
  - Have positive or negative electrical charge
  - Attract one naother
  - Form hard solids: high melting & boiling point