Chapter U1.11, Problem 6E

Interpretation Introduction

Interpretation:

The revised plum pudding model that includes protons needs to be explained.

Concept introduction:

According to the Thomson experiment, if the electric discharge from a high potential source is passed through a discharge tube evacuated to pressure around 0.1mm or less, rays emitted from the cathode. These are called cathode rays. These rays travel in straight lines at right angles to the cathode surface. They produce mechanical motion in small paddle wheel placed in their path indicating that that are material particles. These particles are deflected form their path by electric path and magnetic fields showing that they are electrically charged. The direction of deflection indicates that they are negatively charged . These particles are called electrons.

Also, in the experiment, if the discharge tube contains perforate cathode which emitted another type of radiation which start from the side by side of the anode and pass through the holes of the cathode.

The radiation carrying the positive charge is positive rays or anode rays. Further it is discovered that there are positively charged particles in these rays. These positive charged particles are named protons.

Explanation of Solution

The plum pudding model of an atom explains that electrons are surrounded by a positively charged volume. In the model, plums are refereed to negatively charged particles and pudding is positively charged. This model is known as Thomson’s plum pudding model.

Now, if protons where discovered after electrons, the plum pudding model can be revised with positive charged particles at the center (occupying very less space) which are surrounded by negatively charged particles.

The number of positive and negative charged particles will be same as atom is neutral in nature. The revised plum pudding model will be: