what are contibutions jj tomson made to the atomic theory and the experiment he conducted to find his dicovery
who is tomson? Never heard of him.
http://en.wikipedia.org/wiki/J._J._Thomson
sorry, jj thomson
J.J. Thomson made several significant contributions to the atomic theory, particularly in the area of the structure of the atom and the discovery of subatomic particles. His experiments using cathode rays led to the identification of the electron and helped shape our understanding of atomic structure.
To understand J.J. Thomson's contributions to the atomic theory and his experimental setup, let's break it down into three key areas:
1. Cathode Ray Tube Experiment:
J.J. Thomson conducted experiments using a cathode ray tube, a sealed glass tube containing a partial vacuum. In this experiment, he observed a ray of light from the cathode (negatively charged electrode) to the anode (positively charged electrode) inside the tube. Here's the experimental setup:
- A cathode ray tube: This is a glass tube with two electrodes: a negatively charged cathode and a positively charged anode.
- A high-voltage power supply: This provides the necessary voltage to accelerate the electrons.
- A vacuum pump: Used to create a partial vacuum inside the tube.
- A phosphorescent screen: Placed at one end of the tube to illuminate when struck by the electrons.
When a high voltage was applied across the electrodes, a ray of unknown particles called cathode rays appeared to travel from the cathode to the anode. Thomson noticed that the path of these rays was not affected by changes in the material of the electrodes or the gas inside the tube.
2. Discovery of the Electron:
To investigate the nature of cathode rays, Thomson placed electric and magnetic fields around the cathode ray tube. He observed that the ray was deflected by both electric and magnetic fields. Based on this observation, he concluded that cathode rays were composed of negatively charged particles.
Thomson proposed that these negatively charged particles were fundamental subatomic particles, which he named "electrons." This discovery challenged the previous understanding that atoms were indivisible and presented the idea that atoms were made up of smaller, negatively charged particles.
3. Plum Pudding Model:
Building upon his discovery of the electron, Thomson proposed a new atomic model known as the "Plum Pudding" model. According to this model, an atom was considered as a positively charged sphere with electrons embedded in it, similar to raisins in a plum pudding. The positive charge balanced the negative charge of the electrons, preserving overall electrical neutrality of the atom.
In summary, J.J. Thomson's key contributions to the atomic theory include the discovery of the electron and his proposal of the Plum Pudding model. These contributions were made possible through his experiments using cathode rays in a cathode ray tube.