States of matter

• What are the three states of matter?

  Solid, liquid, and gas
• What determines the state of a substance at a certain temperature?

  The strength of the forces of attraction between the particles
• What are the three factors that affect the strength of forces of attraction between particles?


  The material, temperature, and pressure
• How does particle theory explain the behavior of particles in solids?


  • Strong forces of attraction hold particles close together
  • Particles are in fixed positions forming a regular lattice
  • Particles vibrate about their positions
  • Solids have a definite shape and volume
• What happens to the particles in a solid when it is heated?


  The particles vibrate more and the solid expands slightly
• How does particle theory explain the behavior of particles in liquids?


  • Weak forces of attraction between particles
  • Particles are randomly arranged and can move past each other
  • Liquids have a definite volume but no definite shape
  • Particles move with random motion and expand slightly when heated
• What is the effect of heating a liquid on its particles?


  The particles move faster and the liquid expands slightly
• How does particle theory explain the behavior of particles in gases?


  • Very weak forces of attraction between particles
  • Particles are far apart and free to move
  • Gases have no definite shape or volume
  • Particles move constantly with random motion and expand when heated
• What happens to gas particles when they are heated?


  The particles move faster, causing the gas to expand or increase in pressure
• What are the limitations of particle theory in explaining the states of matter?


  • Particles are not solid or inelastic
  • Particles are not perfect spheres
  • The model does not show the forces between particles
• What do state symbols indicate in a chemical equation?


  They indicate the physical state of the reactants and products
• What are the state symbols for solid, liquid, gas, and aqueous?


  (s) for solid, (l) for liquid, (g) for gas, (aq) for aqueous
• What does 'aqueous' mean in a chemical equation?


  'Aqueous' means 'dissolved in water'
• Write the balanced equation for the reaction of aqueous hydrochloric acid with solid calcium carbonate.


  2HCl_(aq) + CaCO_3(s) → CaCl_2(aq) + H₂O_(l) + CO_2(g)