Discovery of proton

DISCOVERY OF PROTON

The existence of protons in the atoms was shown by E. Goldstein.
E. Goldstein, a German scientist repeated the Thomson’s experiment by modifying the discharge tube.
He used a perforated cathode and it was placed in the centre of the tube.
Hydrogen gas was enclosed in the discharge tube and the experiment was performed a was with cathode ray tube.
He found that rays were emitted in the tube which passed through the perforations in the cathode and moved away from the anode.
E. Goldstein called these rays canal rays.
The rays were later named as anode rays as they were directed away from the anode.

The origin of anode rays:

The discharge tube contains Hydrogen gas in it.
Under high voltage, these molecules break into atoms of hydrogen.
The high speed electrons which constitute the cathode rays collide with hydrogen atoms.
As a result, electrons are knocked out of these atoms leaving behind positively charged residues. These positively charged residues constitute the anode rays and move through the perforations of cathode.
Hydrogen gas was enclosed in the discharge tube, so these positively charged residues were called protons. Proton arises from the word protium which represents hydrogen atom.
When experiment was performed with some other gas the positive residues were different and were actually aggregate or multiple of protons.
A proton is usually represented by the symbol p*.

Characteristics of anode rays:

Anode rays travel in straight line.
Anode rays consist of positively charged particles known as protons.
The nature of anode rays depends upon the gas enclosed in the discharge tube.
Anode rays are deflected by electric field and magnetic field in a direction opposite to the cathode rays.
The specific charge (e/m ratio) is not the same for all the gases enclosed in the discharge tube.

Characteristics of a Proton:

The charge of a proton is equal and opposite to the charge of an electron i.e. 1.602 × 10^–19Coulomb
Relative charge of a proton is +1.