Analía Bellizzi – Chemistry Classes

Ronald Reagan High School

Matter Notes IGCSE #1-1

All is Made of Particles

  • Matter is everything that has mass and occupies space.
  • All matter is made of particles.
  • We know three types of state of the matter: solids, liquids and gases. (Plasma is a fourth state of the matter that we do not analyze at this level)
  • Particles are arranged differently in solids, liquids or gases.

The Particle Theory of Matter:

1. Matter is made up of tiny particles (Atoms, ions or Molecules)
2. Particles of Matter are in constant motion.
3. Particles of Matter are held together by very strong electric forces.
5. Each substance has unique particles that are different from the particles of other substances
6. Temperature affects the speed of the particles. The higher the temperature, the faster the speed of the particles.
7. Particles only stop moving when they reach the ABSOLUTE ZERO temperature (-273.15 °C = 0.00 K)


  • Particles of solids are packed together and held in their positions by strong electrostatic forces.
  • Particles of solids vibrate constantly due to their internal (Kinetic) energy but they cannot move from one place to another.
  • The attraction forces are higher than the internal energy. (they cannot escape from the “NET” where they belong.
  • The hotter the substance, the more Kinetic Energy it will have and the more movement in the particles.
  • They have vibrational energy only. (They cannot rotate or move around)

Here you have 3 examples of SOLID particles at different temperatures:

particles DO NOT MOVE at all

At low temperatures particles
vibrate in their own place

The hotter the solid gets,
the faster the particles move

Solids – some more properties

  • Solids have a fixed shape and volume
  • Because the particles are packed together, solids cannot be compressed or flow

Solids cannot flow or be compressed

solids cannot be compressed


  • Particles of liquids are kept together by forces of attraction that are weaker than those of solid particles. 
  • They do not belong in a fixed position. They can move freely but the energy is not enough to escape from the container. 
  • The movement is in all directions with different speeds, this is called RANDOM MOVEMENT.
  • This property of move freely in the container allows liquids to “flow” and to get the container’s shape.
  • The internal energy of a liquid is bigger than the one in solids.  
  • From time to time, some of the particles can reach enough energy to escape the container (evaporation)

Liquid particles move 
randomly and packed together

Liquids – some more properties

  • Liquids have not shape
  • They can flow because of the weaker force of attraction between particles
  • Because the particles are packed together, liquids cannot be compressed.

Liquids can flow but cannot be compressed because of the proximity of their particles. 


  • The forces of attraction that hold gas particles together are very weak.
  • The spaces between the particles are much larger than the spaces between solid and liquid particles.
  • Gases movement are also random. (in any direction and with different speeds
  • Particles of gases can move freely within a container bumping against the walls and other particles.
  • They move, rotate and vibrate at the same time. 
  • They can escape from a container very easily and they can put pressure on the side of the container.

Gas particles move randomly
very separated from each other.
Most of the container is considered empty space.

Gases – some more properties

  • Gases have no shape.
  • They can flow because of the weaker force of attraction between particles
  • Because the particles are spread apart gases can be compressed.
  • They flow in all directions. 

Gases can flow  in all directions and can be compressed


Gases move in all directions. The first scientist to discover the evidence of this movement, was Robert Brown. That is why this “Random Movement” is also called “Brownian Movement”

Because of this “Brownian Movement” gases bounce against each other and against the walls, spreading apart. These movements which make the gas “travel” through air, is what we call Diffusion 

Diffusion occurs in gases and liquids

Diffusion in liquids:

Diffusion also occurs in liquids, since the particles are free to move. 

Solid particles are held in the crystal lattice (network) so they cannot diffuse, but when dissolved, they can use the water molecules and they can diffuse. If two substances get in contact (collide) they can react to form a new substance. 

Plasma – the forgotten state:


  • Plasma is formed by electrically charged atoms called ions