Describe briefly Thomson model of an atom.

Thomson proposed that the shape of an atom resembles that of a sphere having a radius of the order of 10^-10 m. The positively charged particles are uniformly distributed with electrons arranged in such a manner that the atom is electrostatically stable. Thomson’s atomic model was also called as the plum pudding model or the watermelon model. The embedded electrons resembled the seed of watermelon while the watermelon’s red mass represented the positive charge distribution. The plum pudding atomic theory assumed that the mass of an atom is uniformly distributed all over the atom.