Question

Explain why both Thomson and Rutherford's experiments unable to deduce the existence of the neutron?

Answer 1

Answer:

The neutron is a particle without charge, so it could not be detected easily or directly by the Thomson and Rutherford experiments, since in their experiments negative and positive charge rays were used .

Explanation:

The atomic models of Thomson and Rutherford were the first models that tried to explain how an atom was formed.

It is currently know that an atom is made up of three fundamental particles: proton (positive charge), electron (negative charge) and neutron (no charge). This is known due to the different experiences that several scientists made throughout history.

One of the first ideas on how the atom was formed was proposed by Thomson. He assumed that the positive charge was distributed equally throughout the atom while the negative charges were embedded in the atom like plums in a pudding (that's why it is known as the "Plum Pudding Model"). That is, so far, Thomson's model only spoke of positive and negative charges.

It was Thomson who studied negatively charged particles in detail and gave them the name of electrons, he made his experiments with the "Cathode Ray Tube", a tube with negative electrical charge rays. In addition, Thomson was able to discover that electrons had mass.

A few years later, the physicist Rutherford (Thomson's student) discovered through an experiment that in reality each atom had a very small and dense center with a positive charge, which he called the atomic nucleus. Rutheford's experiments were performed with alpha particles, that is, positively charged particles.

Answer 2

Atom is composed of Neutrons, protons and electrons.

Two scientists tried to discover the nucleus but their discovery was not sufficient.

Rutherford's model or Gold-Foil experiment : He took a Gold foil & passed Alpha- particles ($_2^4\alpha$ - carrying 4+ charge) He put a photogenic film around the foil to see where the particles are going. He assumed that the $\alpha$-particles would pass through the foil because it was very thin. But to his surprise he found an opposite observation. He found that the particles bounced back. This observation would either mean that the particles are either hitting something very hard or something carrying positive charge as positive charges repel each other. So he made a point that the nucleus has some positive charge that is composed of protons and therefore could not explain anything about neutrons.

Thomson's model or Plum-Pudding Model :  He proposed a theory just after the discovery of electrons. He proposed that an atom is similar to a sphere carrying positive charge in which electrons (negatively charged ) are present. His model was similar to the plum pudding or watermelon in which electrons look similar to the dry fruits which were embedded in the pudding that resembled a positive charged sphere. Similarly, in watermelon, the red edible part resembles the positively charged sphere whereas the seeds resembles the electrons. He proposed that the atom is neutral as the positive and negative charges are equally balanced. His model was unable to describe the nucleus of the atom and thus was unable to describe the neutrons.