Chapter 4, Problem 39A

a)

Interpretation Introduction

Interpretation : The experimental evidence was given by Thomson for the statement to be explained.

Concept Introduction : Thomson was the person behind the discovery of electrons that revolve around the nucleus. Thomson conducted tests with the flow of an electric current through low-pressure gases.

Answer to Problem 39A

Thomson's claim that electrons have a negative charge is supported by experimental data showing that electrically charged metal plates can deflect cathode rays that are drawn to positively charged plates.

Explanation of Solution

Thomson tested low-pressure gases while an electric current was running through them. Gases were contained by him in glass tubes with metal disc electrodes attached at both ends.

The only positively charged electrode was the anode electrode. The opposite electrode, the cathode, generated a negative charge. As a result, a glowing beam known as a cathode ray was created and traveled from the cathode to the anode.

Thomson discovered that a cathode ray can be deflected by electrically charged metal surfaces. Positively charged plates attract the cathode ray, whereas negatively charged plates reject it.

Since the cathode rays are attracted towards a positively charged plate while it is repelled by a negative charge, Thomson stated that electrons have a negative charge.

b)

Interpretation Introduction

Interpretation : The statement given by Dalton is to be agreed upon or not to be explained.

Concept Introduction : Thomson was the person behind the discovery of electrons that revolve around the nucleus. Thomson conducted tests with the flow of an electric current through low-pressure gases.

Answer to Problem 39A

Thomson's claim that electrons are present in the atoms of every element is supported by experimental data showing that the charge-to-mass ratio of electrons remains constant under a variety of circumstances.

Explanation of Solution

Thomson tested low-pressure gases while an electric current was running through them. Gases were contained by him in glass tubes with metal disc electrodes attached at both ends.

The only positively charged electrode was the anode electrode. The opposite electrode, the cathode, generated a negative charge.

As a result, a glowing beam known as a cathode ray was created and traveled from the cathode to the anode.

Thomson designed an experiment to determine the charge-to-mass ratio of an electron to test his theory. He discovered that this ratio was constant. The type of gas utilized in the cathode ray tube, or the metal employed for the electrodes did not affect the charge-to-mass ratio of electrons. Thomson concluded that electrons are a part of every element's atom.

Though different gas was utilized, the charge-to-mass ratio of electrons remained the same, this was the experimental evidence that electrons are a part of every element’s atom.