PARTICLE THEORY AND
THE STATES OF MATTER
ALL MATTER IS MADE UP OF TINY
PARTICLES
• This is true for everything in the universe, solids,
liquids, gases, and plasmas!
WHAT ARE PARTICLES?
Democritus (400 B.C.) philosophised that if you started
cutting anything in half, over and over again,
eventually you would reach a point where the object
would be indivisible. This is what he called the atom.
WHAT ARE PARTICLES? (CONT.)
• Eventually scientists discovered that atoms were
made up of protons, neutrons, and electrons.
• Scientists now know that protons and neutrons are
made up of quarks and that these could be
potentially be made up of even smaller strands of
energy called strings.
THE PARTICLES ARE IN CONSTANT
MOTION
• The particles in all matter, are always moving
because they all contain energy. This may be
obvious in liquids and gases, but even in the most
solid of things (like your desk), the particles are in
constant motion!
THE PARTICLES OF THE SAME MATTER
ARE THE SAME
• For example, all particles of water in the world are
made up of two hydrogen atoms, and one oxygen
atom!
THERE IS SPACE BETWEEN THE
PARTICLES.
• Actually, the space between the particles is larger
than the particles themselves. This is even true for
solids. They particles need space to move.
THERE IS ATTRACTION BETWEEN LIKE
PARTICLES
Water particles are attracted to other water particles.
Nitrogen particles are attracted to other nitrogen
particles. Helium particles are attracted to other
helium particles. Gold particles are attracted…I think
you get the point!
5 POSTULATES OF THE PARTICLE
THEORY OF MATTER
• All matter is made up of tiny particles
• The particles are in constant motion
• There is space between the particles
• Particles of the same matter are the
same
• There is attraction between like
particles
SOLIDS
Solids have a definite shape, because the particles
have less energy, which means they move slower,
have more attraction and less space between them.
The particles vibrate in a lattice like pattern.
LIQUIDS
Liquids take the shape of the container they are in,
because the particles have more energy than solids,
which means they move faster, have less attraction
and more space between them. The particles move
freely around each other.
GASES
Gases fill whatever space is available to them,
because the particles have even more energy than
liquids, which means they move even faster, have
nearly no attraction and a lot more space between
them. The particles move freely around everywhere.