States of Matter

• Solid state


  • Particles are compactly packed in a lattice and vibrate in a fixed position
  • Solid has a definite mass, shape, and volume
  • Solid does not flow and is hard to compress
• Gases expand more readily than solids at a given temperature


  Less energy is required to overcome intermolecular forces
• Basis for classifying matter

  • Particle arrangement
  • Energy and motion of particles
  • Distance between particles
  • Strength of attraction between particles
• Particulate nature of matter

  • Particles are tiny and invisible to the human eye
  • Inter particle force of attraction exists when particles are close
  • Change in temperature affects particle movement
  • Heavier particles move more slowly than lighter particles at a given temperature
• States of matter

  • Solid
  • Liquid
  • Gas
• Plasma state

  • Plasma is an ionized gas
  • Plasma is a good conductor of electricity and affected by magnetic fields
  • Plasmas have an indefinite shape and volume
• Evidence for the existence of matter particles:
• Evidence 2

  Place a glass jar upside down on an open glass jar containing red-brown bromine, color spreads upward
• Kinetic particle theory/particulate theory of matter

  1. All matter is made of extremely tiny moving particles

  2. Inter particle force of attraction exists when particles are close

  3. Change in temperature affects particle movement
• Liquid state


  • Particles are close together but not in a fixed position
  • Liquid has a definite mass and volume but no definite shape
  • Liquid flows easily and is hard to compress
• Brownian motion is defined as the random movement of particles
• Gaseous state


  • Particles are far apart and move freely in random motion
  • Gas has neither definite volume nor shape but has definite mass
  • Gas takes up the shape of its container
  • Gas flows easily and is easy to compress
• Plasma is the fourth state of matter
• Gases have maximum energy due to random motion
• Heating curves represent change of physical state with change in temperature
• Presence of impurities increases the boiling point
• Experiment

  1. Place a glass jar upside down on an open glass jar containing a few drops of red-brown bromine

  2. Robert Brown added pollen from flowers to water

  3. Cotton wool soaked in ammonia solution & the other cotton wool soaked in HCl solution is held at the two ends of glass tube
• All gases do not diffuse at the same rate
• Change of state

  1. Solid to liquid - Melting - Heat absorbed - Temperature increases - Particles spread out

  2. Liquid to gas - Vaporisation - Solid to gas - Sublimation

  3. Liquid to solid - Freezing - Heat evolved - Temperature decreases - Particles move closer

  4. Gas to liquid - Condensation - Gas to solid - Deposition
• Rate of diffusion depends on:
• Presence of impurities lowers the melting point and the substance melts over a range of temperature
• Cooling curves
• Study of diffusion


  1. Process in which matter particles mix & spread throughout by colliding with other particles is called diffusion

  2. Diffusion is a random process

  3. The path of the particles depends on collisions

  4. Particles get uniformly distributed throughout
• Mechanisms of diffusion

  • Brownian motion is the seemingly random movement of particles suspended in a liquid or gas
  • Vacancy diffusion or interstitial diffusion in solids
• The ring of white powder is closer to the HCl than the NH3 due to the lighter (smaller) molecules diffusing more quickly through the air
• Brownian Motion can be observed by looking at smoke particles in air through a microscope
• In a liquid or gas, particles move at random, known as Brownian Motion
• Diffusion examples


  • The smell of aftershave or perfume diffuses and is detected by people on the other side of the room
  • Mass transport by atomic motion
  • Material moving from areas of high to low concentration
• The reaction of Hydrogen Chloride and Ammonia to form Ammonium Chloride is reversible
• Diffusion of Hydrogen Chloride and Ammonia Gas through Air to form Ammonium Chloride


  1. Cotton wool soaked in concentrated ammonia solution and concentrated Hydrogen Chloride solution are placed at each end of a sealed tube

  2. HCl and NH3 molecules diffuse through the air towards each other

  3. When they meet, they react to form a white powder called ammonium chloride
• Diffusion


  Movement of particles that allows them to spread out and mix with other particles
• All matters are made of tiny particles such as atoms, ions, or molecules