Question

describe the thomson model of atom

Answer 1

In 1897, J.J.Thomson discovered a negatively charged particle known as an electron. Thomson discovered electron by cathode ray tube experiment. Cathode ray tube is a vacuum tube. Thomson assumed that an electron is two thousand times lighter than a proton and believed that an atom is made up of thousands of electrons having the negative charge. In this model, he considered atoms to have a cloud of negative charge and the positive charges. He along with Rutherford was also the first to demonstrate the ionization of air by X-rays. Thomson’s model of an atom is similar to plum pudding model or a watermelon.

Answer 2

He discovered electrons in 1897. 
He showed us that the atom can be split into even smaller parts.
His discovery was the first step towards a detailed model of the atom .
An atom is a uniform sphere of positive charges (due to presence of protons) as well as negative charges (due to presence of electrons).
 Atom as a whole is electrically neutral because the negative and positive charges are equal in magnitude.
 An electron is a negatively charged component of an atom which exists outside the nucleus. Each electron carries one unit of negative charge and has a very small mass as compared with that of a neutron or proton.
JJ Thomson used cathode ray tubes to demonstrate that the cathode ray responds to both magnetic and electric fields.
Since the ray was attracted to a positive electric plate placed over the cathode ray tube (beam deflected toward the positive plate) he determined that the ray must be composed of negatively charged particles. He called these negative particles "electrons."
Limitation: Model failed to explain how protons and electrons were arranged in atom so close to each other.