chemistry chapter 2: kinetic particle theory

• Physical state of particles can be determined by adding or removing energy, affecting the attractive forces experienced by them
• Factors affecting the rate of diffusion:

  • Effect of temperature:
  • Particles have more kinetic energy at higher temperatures
  • As temperature increases, the rate of diffusion also increases due to greater average kinetic energy
  • More thermal energy is converted to kinetic energy of particles
  • Effect of particle mass:
  • Particles with greater mass require more kinetic energy to move at a given speed
  • Heavier particles diffuse more slowly than lighter particles
• Processes and type of kinetic energy:

  • Absorption of energy to the surroundings:
  • Melting
  • Boiling/evaporation
  • Sublimation
  • Release of energy to the surroundings:
  • Freezing
  • Condensation
  • Vapour deposition
• Properties of energy:

  • Energy is neither created nor destroyed but changes from one form to another
  • During heating/cooling, thermal energy is converted to kinetic energy of particles
• Change of state:

  • When a substance is heated, thermal energy is transferred, some converted into kinetic energy of particles
  • 6 states of transition: melting, freezing, boiling, condensation, sublimation, vapour deposition
  • During state transitions, temperature remains constant and substance exists as a mixture of 2 physical states
• Solid contraction:

  • When a solid is cooled, thermal energy is transferred from particles to surroundings
  • Particles possess less kinetic energy, vibrate slower, come closer together, solid undergoes contraction
• Solid thermal expansion:

  • When a solid is heated below its melting point, particles vibrate more quickly with slightly wider spacing
  • Solid undergoes expansion
• Diffusion:

  • Net movement of particles from higher to lower concentration regions
• Temperature:

  • Measure of average kinetic energy of particles in a substance
  • During state changes, temperature remains constant as average kinetic energy does not change, thermal energy converted into chemical potential energy
• Arrangement of particles:

  • DAME:
  • Distance
  • Attractive forces
  • Movement
  • Energy
• Arrangement of particles in gas:

  • Particle spacing large, weak attractive forces
  • Particles far apart in disorderly manner, move quickly and randomly
  • High kinetic energy, no definite volume or shape
• Arrangement of particles in liquid:

  • Particle spacing larger than in solids, less strong attractive forces
  • Particles closely packed in disorderly manner, can slide past one another freely
  • Low kinetic energy, definite volume but no definite shape
• Arrangement of particles in solid:

  • Particles closely packed in orderly manner, vibrate and rotate about fixed positions
  • Low kinetic energy, strong attractive forces, definite shape
• Expansion and contraction of solids:

  • Gaps left between track segments for expansion on hot days and prevent derailment
• Kinetic particle theory:

  • All matter made of tiny particles in constant motion (Brownian motion)
  • Explains properties of solids, liquids, gases, temperature changes, changes of states, expansion, and contraction
• Process of boiling:

  • Thermal energy converted to kinetic energy, particles slide past each other with increasing speed
  • Temperature rises towards boiling point, particles overcome strong forces of attraction, move further apart
  • Temperature remains constant until all liquid boils and becomes gas
• Process of condensation:

  • Kinetic energy converted to thermal energy, transferred to surroundings
  • Particles slow down, temperature reduces towards condensation point
  • Particles drawn closer together, temperature remains constant until all gas condenses to liquid
• Process of freezing:

  • Kinetic energy converted to thermal energy, transferred to surroundings
  • Particles slow down, temperature reduces towards freezing point
  • Particles drawn closer together, temperature remains constant until all liquid freezes to solid
• Process of melting:

  • Thermal energy converted to kinetic energy, particles vibrate and rotate faster
  • Temperature rises towards melting point, particles overcome strong forces of attraction
  • Temperature remains constant until all solid melts to liquid
• Process of sublimation:

  • Under certain conditions, some substances can sublime
  • Thermal energy from surroundings converts solid to gas
  • Temperature remains constant until all solid has sublimed
  • Applications: dry ice, iodine, naphthalene, ammonium chloride
• Process of vapour deposition:

  • Some substances change directly from gas to solid
  • Particles cooled until they arrange into solid state
  • Temperature remains constant until all gas becomes solid
  • Example: iodine vapour forms crystals on cold glass surface
• Reason for state of substance:

  • Attractive forces vary between substances
• Solids do not undergo diffusion:

  • Particles can only vibrate and rotate about fixed positions, cannot move around
  • Diffusion occurs only in liquids and gases
• When a substance is heated, thermal energy is converted into kinetic energy of the particles
• As a substance is heated, particles vibrate and rotate faster about their fixed positions, leading to a rise in temperature towards the melting point
• At the melting point, particles with increased energy can overcome the strong forces of attraction in the solid state
• This allows the orderly packing arrangement of particles to be disrupted, enabling the particles to slide past one another freely throughout the liquid
• The temperature remains constant throughout the melting process until all the solid melts and becomes a liquid
• When a substance is heated, thermal energy is converted into kinetic energy of the particles. Hence, the particles slide past one another with increasing speed and the temperature of the substance rises to the boiling point. At the boiling point, the particles with increased energy are able to overcome the strong forces of attraction in the liquid state. Hence, the particles move further apart, quickly and randomly. The temperature remains constant throughout the boiling process until all the liquid boils and becomes a gas.
• When a substance is cooled, the kinetic energy of the particles is converted into thermal energy that is transferred to the surroundings
• With less kinetic energy, the particles slow down and the temperature of the substance reduces towards the freezing point
• At the freezing point, particles with less energy are drawn closer by the forces of attraction between them
• The particle arrangement becomes more orderly at the freezing point, allowing particles to vibrate and rotate about their fixed positions
• The temperature remains constant throughout the freezing process until all the liquid freezes and becomes a solid
• When a substance is cooled:

  • Kinetic energy of particles is converted into thermal energy which is transferred to the surroundings
  • With less kinetic energy, the particles slow down and the temperature of the substance reduces towards the condensation point
• At the condensation point:

  • Particles with less energy are drawn closer by the forces of attraction between them
  • Particle arrangement becomes less disorderly and the particles can slide past one another throughout the liquid only
• During the condensation process:

  • The temperature remains constant until all the gas condenses and becomes a liquid