Question

In the Rutherford experiment, \[\alpha - \] particles are scattered from a nucleus as shown. Out of the four paths, which path is not possible?

A. D
B. B
C. C
D. A

Answer 1

Hint: To answer this question, one must know Rutherford’s experiment details and the structure of Rutherford’s model of an atom. The dispersion of \[\alpha - \] particles in Rutherford's experiment revealed for the first time that the atom has a nucleus. He noticed that the positive charges in the atom repelled and deflected the positively charged \[\alpha - \] particles. This positively charged area of the atom was given the term "nucleus" by Rutherford.

Complete step by step solution:
We know that like charges repel whereas unlike charges attract. Using this concept along with the knowledge of Rutherford’s model of an atom, we will get the required answer. The structure of alpha particles, also known as alpha rays or alpha radiation, is similar to that of the helium-4 nucleus and is made up of two protons and two neutrons bonded together. They are often formed during the alpha decay process, although they can also be produced by other processes.

The \[\alpha - \] particles carry $ + 2e$ charge on them ( $e$ is the charge of a single electron/proton). Also, the nucleus carries a charge of $ + Ze$ where $Z$ is the atomic number of the atom. Both these particles carry positive charge therefore, the electrostatic force between them is repulsive in nature.

In path D., the \[\alpha - \] particle is going away from the nucleus due to repulsion. Therefore, path D. is possible. In path B., the \[\alpha - \] particle is bouncing back due to repulsion, therefore, this path is also possible.Similarly, in path A., the \[\alpha - \] particle gets repelled by the nucleus and goes away from it. Hence, path A. is also possible.

Whereas in path C. the distance between the \[\alpha - \] particle and the nucleus is decreasing which implies that the \[\alpha - \] particle and the nucleus are attracting each other, which is not true. Therefore, path C. is not possible.

Hence, option C is the answer.

Note: An atom's positive charge and the majority of its mass are concentrated in its tiny nucleus, which serves to resist any incoming positive charges. According to Rutherford's theory, an atom's nucleus is surrounded by electrons that are negatively charged. He also asserted that the electrons that surround the nucleus travel in a circular pattern at extremely high speeds. He gave these elliptical routes the name orbits.