Thomson's Model is also known as Plum Pudding Model. From the beginning of Chapter 12 of Class 12 Physics, you will study about the many atomic model theories. The Thompson Model is one of them. The atom is said to be like a plum or a watermelon in this concept. There is a reddish orangish fleshy portion with seeds embedded in it, similar to watermelon or plum. Thompson believed that the positive charge of the atom is represented by the fleshy section, while the negatively charged electrons are represented by the seeds.