In discovery of atom, we all know hos Democritus coined the term Atomos
and how he said that it was the smallest particle and atomos means it was
uncuttable.
Delton then gave his atomic theory when he said that atoms are actually the
smallest particles of matter and atoms of different elements from each other in
their masses but atoms of the same element are identical and that atoms of
different elements,they combine together to form compound atoms. Today we
know as compounds. But this was an 1808 when scientist did not know about
subatomic particles.
As the century progressed in by the end of the century in 1897, J.J Thompson
and other scientists, were working on atoms and they were trying to find out
what are the properties of atoms and structure. So they are carrying out lots of
experiments.
Thompson carried out an experiment in a discharge tube. Imagine the
discharge tube to be somewhat like a tube light that you have in your rooms.
The tube light is a glass tube and it has a fluorescent coating on it which is
when it lights up you can see the light. The two ends of the tube light has a
metallic plate that looks like a disc and it is connected to the electric source
which produces electricity, to produce the beam of light and to illuminate the
tube light.