Question

Plum pudding model of atom was given by:
(A) Thomson
(B) Rutherford
(C) Bohr
(D) Chadwick

Answer 1

Hint: Electrons were discovered by conducting the experiments with cathode-ray tubes and these are the negatively charged subatomic particles present in the atom.
- The plum pudding model is also called the watermelon model of atoms.

Complete answer:
The question is about who has discovered the Plum pudding model of the atom. Before answering the question who discovered it, let’s see why it is called so and what was its relevance to this model.
The plum pudding model was suggested around 1940, then the concept of nucleus was not introduced.
The negatively charged subatomic particle i.e. electrons was discovered during 1897 by J.J. Thomson.
- This model explained how an atom could look like, what particles it contains and how they would be arranged in it. The name plum pudding is because of the resemblance of the atom structure with plum pudding. This model gives an idea that an atom is a spherical shaped structure which is entirely filled by positive charge (protons) into which negative charged electrons are randomly embedded into it. This could be compared to pudding as the spherical atom occupied by positive charge and the plums as electrons spread in it. According to this model, matter is made up of small spherical particles of about ${{10}^{10}}m$ in size, they are spread by the positive charge throughout its volume called pudding and the negative charged particles are distributed in it as point charges called as plum. And hence this model was given the name plum pudding model.
- After the discovery of the electrons by J.J. Thomson, by carrying out the cathode ray experiment, he suggested this plum pudding model of atom.
- So J.J. Thomson is the person who suggested the first model of atom as is called Thomson's model of atom or plum pudding model of atom.
So, the correct answer is “Option A”.

Additional Information: Plum pudding model is also called the watermelon model of atoms, since if it is compared to a watermelon, the positive charge is the fleshy red portion and the electrons are just spread like the seeds in it.

Note: Thomson’s atomic model failed to explain the light spectrum with different frequencies and alpha ray deflection by an atom. So another satisfactory model came by the scientist Rutherford given by the alpha ray scattering experiment.