Question

explain JJ Thomson atomic model
with figure limitation, drawback and conclusion give three three point of each

Answer 1

J. J. Thomson, who discovered the electron in 1897, proposed the plum pudding model of the atom in 1904 before the discovery of the atomicnucleus in order to include the electron in the atomic model. In Thomson's model, the atom is composed of electrons (which Thomson still called “corpuscles,” though G. J.

Thomson's atomic model failed to explain how the positive charge holds on the electrons inside the atom. It also failed to explain an atom'sstability. The theory did not mention anything about the nucleus of an atom. It was unable to explain the scattering experiment of Rutherford.

Thomson realized that the acceptedmodel of an atom did not account for negatively or positively charged particles. Therefore, he proposed amodel of the atom which he likened to plum pudding.

Answer 2

Before the discovery of subatomic particles, John Dalton came up with Dalton’s atomic theory where he suggested that atoms are indivisible particles. It explained atoms cannot be broken down into further smaller particles. However, the discovery of subatomic particles disapproved the postula
tes proposed in Dalton Atomic Theory.

The discovery of subatomic particles led to the search how the subatomic particles are arranged in an atom. J.J. Thomson was the first and one of the many scientists who proposed models for the structure of an atom. J.J. Thomson discovered negatively charged particles by cathode ray tube experiment in the year 1897.

The particles were named electrons. J.J Thomson believed electrons to be two thousand times lighter than a proton. He assumed that an atom is composed of a cloud of negative charge in a sphere of positive charges. J.J Thomson and Rutherford first demonstrated the ionization of air in x rays.



Thomson Model of an atom

The description of Thomson’s atomic model is one of the many scientific models of the atom. It was proposed by J.J Thomson in the year 1904 just after the discovery of electrons. However, at that time the atomic nucleus was yet to be discovered. So, he proposed a model on the basis of known properties available at that time. The known properties are:

Atoms are neutrally chargedNegatively charged particles called electrons are present in an atom. Learn about .

Thomson’s Atomic Model- Postulates

According to the postulates of Thomson’s atomic model, an atom resembles a sphere of positive charge with electrons (negatively charged particles) present inside the sphere.The positive and negative charge is equal in magnitude and therefore an atom has no charge as a whole and is electrically neutral.Thomson’s atomic model resembles a spherical plum pudding as well as a watermelon. It resembles a plum pudding because the electrons in the model look like the dry fruits embedded in a sphere of positive charge just like a spherical plum pudding. The model has also been compared to a watermelon because the red edible part of a watermelon was compared to the sphere having a positive charge and the black seeds filling the watermelon looked similar to the electrons inside the sphere

Limitations of Thomson’s Atomic Model

Thomson’s atomic model failed to explain how the positive charge holds on the electrons inside the atom. It also failed to explain an atom’s stability.The theory did not mention anything about the nucleus of an atom.It was unable to explain the scattering experiment of Rutherford.


 

Conclusion

Even though Thomson’s atomic model was inaccurate and had a few drawbacks, it provided the base for several other atomic structure models afterward. It is one of the foundation models that led to significant and revolutionary inventions later.