2.1

• Definition of matter

  Tiny and discrete particles
• Matter can be classified into elements (made of one type of atom) and compounds (made of two or more types of atoms)

  
• Atoms are the basic unit of matter and cannot be broken down into smaller parts
• Molecules are made up of two or more atoms held together by chemical bonds
• Ions are atoms that have lost or gained electrons, giving them a net charge
• The three states of matter are solid, liquid, and gas, with different arrangements and movements of particles

  
• Solid


  • Particles are closely packed in an orderly manner

  • Kinetic energy of particles is low

  • Attraction force between particles is strong
• Liquid


  • Particles are closely packed but not in an orderly manner

  • Kinetic energy of particles is higher than solid state

  • Attraction force between particles is strong, but less than solid state
• Gas

  • Particles are far apart

  • Kinetic energy of particles is very high

  • Attraction force between particles is weak
• A


  • The particle are very closely packed together in an orderly manner
  • The force between the particles is very strong.
• A-B

  • The naphthalene is heated the energy is converted to kinetic energy
  • The temperature increase, the kinetic energy increase and the molecules vibrate faster about their fixed position.
• B

  • The naphthalene molecules have received enough energy to overcome the force of attraction between them.
  • Some of the molecules begin to move freely.
  • The naphthalene starts to melt and changes into a liquid.
• B-C

  • Naphthalene exists in both state, solid and liquid.
  • The temperature remains constant because the heat is used to overcome the force of attraction.
  • The constant temperature is called the melting point.
• C


  The napthalene has turned into liquid completely
• C-D


  • The naphthalene is in the liquid state
  • The temperature keeps increasing and gain more energy.
  • The particle is then moving faster because the kinetic energy is increasing.
• Cooling curve of naphtalene

  
• P

  • The substance exists in the gaseous state
  • Have very high energy and moving randomly
  • The intermolecular force is weak.