Chapter 4, Problem 51A

Interpretation Introduction

Interpretation:

The discovery of the nucleus by Rutherford needs to be explained.

Concept introduction:

A radioactive source emits alpha particles (positively charged particles). Like charges repels each other and unlike charges attract.

Answer to Problem 51A

In the Rutherford experiment, the radioactive particle was used to detect the direction of the beam and its nature. The center portion is known as the nucleus.

Explanation of Solution

Rutherford set up the experiment as the alpha particle goes in high speed. A small slit in the screen makes the alpha particle able to stuck in. The alpha particle would penetrate the gold foil. Alpha particles are positive. So they get repel by the positive region but it was found that some part of a beam goes in a straight-line, some have deviated from its path, and some reverse to the sources.

It explains that only a small region at the center point is positive. And it is discovered as the nucleus of an atom. All of the positive charges of protons and all mass of an atom are concentrated in a very small area and the remaining region of the atom is mostly empty.

Gold foil experiment

Conclusion

• Alpha particles went straight through gold foil suggested that atom mostly composed of open space consisting of negatively charged particles know as electrons.

• Alpha particles deflected slightly were passed by touching any positively charged particle.

• Alpha particles bounced back toward the source have encountered with a positively charged and heavy particle known as the nucleus.