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.

Postulates of J. J. Thomson's model of an atom?

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On the basis of Thomson’s model of an atom, explain how the atom is neutral as a whole.