Class 11 Chemistry Structure of Atom Discovery Of Proton



  • In 1836 the same experiment was carried out where the same conditions were provided. The gas at low pressure was taken and current was passed.


  • The high voltage between the electrodes was passed. It was found that when cathode rays passed through the gas, they ionized the gas by taking electrons along, leaving behind positively ionized gas particles.


  • These particles were travelling towards cathode.These particles were found to form the beam of rays of positively charged particles and were called as canal rays.


  • These rays consist of positively charged particles called a proton.

Properties of anode rays

  1. They also travel in straight line.
  2. They are also made up of particles.
  3. They carry positive charge.
  4. Their ratio of charge to mass was different for different gas that was taken in tube.
  5. The mass of particles were found to be different for different gases. It was nearly equal to the mass of atom.

When hydrogen gas was taken in the tube its mass was found to be minimum. As we know, Hydrogen atom is the lightest one and its charge to be same as Electron. It is 1.6x10-19C and its e/m ratio taken as standard that is 1.67x 10-24g.

Proton is defined as a

fundamental particle which carries one-unit positive charge and mass nearly same as hydrogen atom.”

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