DISCOVERY OF PROTON OR DISCOVERY OF CANAL RAYS: In 1886, GOLDSTEIN observed that in addition to cathode rays , other rays were also present in the discharge tube. These rays were travelling in opposite direction to cathode rays. He used a discharge tube having perforated cathode that is holes were present in cathode. He found that these rays passed through holes present in the cathode and produced a glow on the walls of the discharge tube. He called these rays as Canal rays.
CHARACTERISTICS OR PROPERTIES OF CANAL RAYS: The important properties of canal rays are as follow:
1)These rays travel in a straight line in a direction opposite to cathode rays.
2)Their deflection in electric and magnetic field proved that these are positively charged.
- The nature of canal rays depends upon the nature of gas present in the discharge tube.
- These rays do not originate from anode but in fact these are produced when the cathode rays or electrons collide with the residual gas molecules present in the discharge tube and ionize them. Example M + e- → M++ 2e–
“M” in chemistry stands for any general element (3rd group element).
5)Mass of these particles was found equal to that of a proton or simple multiple of it. The mass of a proton is 1840 times more than that of an electron.
RESULTS OR CONCLUSIONS: Following are the major conclusions which can be made from above above discussions about the nature and mass of these canal rays. 1)These rays are made up of positively charged particles called protons. 2)The mass and charge of these particles depend upon the nature of the gas present in the discharge tube. 3) Positive particles produced by the gas will be of the same type that is positive rays produced by the lightest gas hydrogen contain protons.