John Dalton was the first scientist
to give the structure of an atom.
According to him, an atom is a solid,
hard sphere. It is electrically neutral,
that is, it has no charge in it.
So, this was the structure proposed by
John Dalton. It is a solid, hard sphere
Some years later, a scientist named William
Crookes
performed an experiment using this apparatus.
This is known as a Cathode Ray Tube.
He connected this
end to a negative terminal of the
battery and this
end to the positive terminal. This
was the negative terminal
and this was the positive terminal. He then
switched on the battery.
He observed that a beam passed from the
negative
terminal to the positive terminal.
William Crookes called this ray, passing
from the negative terminal to
the positive terminal as Cathode Rays.
In Physics,
you have studied that unlike charges attract, and
like
charges repel. So, if this beam moved from
the negative terminal
to the positive terminal, so that is, it
is attracted towards the positive
terminal
so this should be negatively charged. A
scientist named J.J. Thomson
wanted to verify that this cathode ray
consists
of negatively charged particles. He
repeated the experiment,
and then he brought a negatively charged
rod
near the beam.
So see, as he brings the rod near the beam, it
gets deflected.
It moves away from the negatively
charged rod.
He repeated this. So again, in Physics
you have studied that like charges 
repel,
unlike charges attract. When J.J. Thomson brought
the negatively charged rod
near the beam, it was deflected. It moved away
from the rod.
That means, like charges repel so the
cathode ray consisted of
negatively charged particles.
From this experiment Thomson was able to
conclude
that the cathode rays consist of
negatively charged particles,
which are now called ‘Electrons’.
These negatively charged particles, 
that is, electrons,
are an important part of all atoms.
And, different experiments were performed
which showed that electrons have both, definite
mass
and definite electric charge.
The Cathode Rays were discovered by-
Was it Goldstein, Rutherford, William Crooks
or J.J. Thomson?
So, William Crooks had discovered
the Cathode Rays 
by connecting the ends to the negative and
the positive
terminal. The Cathode Ray connected to
the negative and the positive terminal.
He had discovered the Cathode Rays.
And later on, J.J. Thomson had proven
that the
Cathode Rays consist of electrons. But
initially, the Cathode Rays
were discovered by William Crooks.
Some years later, a scientist named Goldstein,
he performed the same experiment.
He observed that when cathode rays
move from the negative to the positive
terminal,
at the same time, a beam moves from
the positive
towards the negative terminal. So, a
beam
also moves from the positive
to the negative terminal. He
called these
beam as ‘Anode Rays’. So, in Physics, you
know that unlike charges attract. So, if
a beam
moves towards the negative terminal, that
means it should be positively charged.
So, from this experiment it was concluded
that
Anode Rays, that is, the rays moving
from the positive
towards the negative terminal. They
consist of positively charged particles
which are now called
‘Protons’. These positively charged particles
or protons, are an important
part
of all atoms and different experiments
were performed
which showed that these protons have
definite mass and definite electric charge.
Let's revise. This is the negative terminal,
that is the positive terminal.
The beam which moves from the negative terminal
towards the positive terminal is
known as Cathode Rays.
Since it is attracted towards the
positive terminal,
so the particles, electrons, they are
negatively charged.
And the beam which moves from the positive
terminal
towards the negative terminal, it's known
as Anode Rays. It consists of protons.
Since it moves towards the negative
terminal,
that means these protons are positively
charged.
