states of matter

• materials come in ... different forms

  three
• what different forms do materials come in?

  solid, liquid, gas
• what does the state of a material depend on?

  - material (the types of bond)

  - the temperature

  - the pressure
• particle theory


  the concept that all matter is made of exceedingly small particles
• why is the particle theory not perfect?

  particles are not solid, inelastic or spheres - they are atoms, ions or molecules. it also does not show the forces between the particles, so there's no way of knowing how strong they are
• solids


  a state of matter in which the object has a definite shape and volume.
• what causes particles in a solid to be held close together?

  strong forces of attraction between particles
• what happens to the shape and volume of a solid due to the behaviour of its particles?

  particles do not move from their positions, making solids keep a definite shape and volume
• what occurs to the particles in a solid when heated up?

  the hotter the solid gets, the faster the particles move in their positions, causing the solid to expand slightly
• how do particles in a solid behave in terms of their positions?


  particles are in fixed positions to form a very regular lattice arrangement
• solid diagram

  
• liquids


  a state of matter in which the object has a definite volume but no definite shape
• what causes particles in a liquid to be held weakly together?


  weak forces of attraction between the particles
• how do particles in a liquid behave in terms of their positions?

  particles are free to move past each other but stick closely together
• what happens to the shape and volume of a liquid due to the behaviour of its particles?

  liquids have a definite volume but not a definite shape, this makes them flow to fill the bottom of a container
• what occurs to the particles in a liquid when heated up?

  the hotter the liquid gets, the faster the particles move, causing liquids to expand slightly when heated
• liquid diagram

  
• gases


  a state of matter in which the object has no definite volume and no definite shape
• what causes particles in a gas to be held very weakly together?

  very weak forces of attraction between the particles
• how do particles in a gas behave in terms of their positions?

  particles, which travel in straight lines, are free to move past and far apart from each other
• what happens to the shape and volume of a gas due to the behaviour of its particles?

  gases do not have a definite shape or volume and will always fill any container
• gas diagram

  
• what occurs to the particles in a gas when heated up?

  the hotter the gas gets, the faster the particles move - gases expand when heated or their pressure increases
• particles in all states of matter are in constant...

  motion
• why are particles always moving?

  due to heat (which is present in all matter)
• when do particles stop moving?

  at absolute zero (-273.15°C or 0K)
• solid to liquid


  melting
• liquid to gas


  boiling
• gas to liquid

  condensation
• liquid to solid


  freezing
• solid to gas


  sublimation
• gas to solid


  deposition
• when a solid is heated, its particles gain more...

  energy. this makes the particles vibrate more, which weakens the forces that holds the solid together
• at a certain temperature, called the melting point...

  the particles in a solid have enough energy to break free from their positions. this is where solid becomes liquid
• when a liquid is heated...

  the particles get even more energy. this energy makes the particles move faster, which weakens and breaks the bonds holding the liquid together
• at a certain temperature called the boiling point...

  the particles in liquid have enough energy to break their bonds. this is where liquid becomes gas
• as a gas cools...

  the particles no longer have enough energy to overcome the forces of attraction between them, allowing bonds to form between the particles
• at the boiling point...

  so many bonds have formed between the gas particles that the gas becomes a liquid
• when a liquid cools...

  the particles have less energy so move around less. there's not enough energy to overcome the attraction between the particles, so more bonds form between them
• at the melting point...

  so many bonds have formed between the particles that they're held in place. the liquid becomes a solid