States of Matter
More than 2000 years ago a Greek philosopher called
Democritus suggested this hypothesis:
All matter, living and non-living, is made of tiny
particles too small to be seen.
His idea was that if you kept cutting
something into smaller and smaller
pieces you would eventually come to
the smallest possible particles - the
building blocks of matter. He used
the work atomos (which in Greek
means ‘cannot be divided’) to
describe these tiniest particles.
The Particle Theory of Matter
All MATTER is made up of tiny particles
(ATOMS) that are constantly moving.
Solids, liquids and gases have two
important properties - they all have mass
and they all take up space.
Solids Solids include - steel, books and
most of the objects you can see.
They all have mass and occupy space.
The shape and volume of most
solids cannot be easily changed.
Powders are also solids but their
shape can be changed.
Water, milk and oil are all
examples of liquids.
The volume of a liquid does not
change, but its shape can.
Liquids take on the shape of the
container they are in.
Gases The air around us is a gas.
Gases have mass and occupy
Gases do not have a fixed
shape of volume.
A gas fills its container, no matter
what the shape or size of the
container e.g. a balloon.
Gases can be compressed.
Plasma makes up 99% of the
It consists of charged particles
that are even further apart than
the particles in a gas.
You don’t see much plasma on Earth because
it requires very high temperatures. The Sun is
made of plasma, as are all the stars. Lightning
is a type of plasma that occurs naturally on