1.2.2 THOMSON'S ATOMIC MODEL
From the discovery of the electron, Thomson suggested that there are negatively charged particles in the atom. It is also well-known that atom is a neutral particle. Thomson then proposed that there must also be positively charged particles to balance the negatively charged electrons. His atomic model called"raisins in a plum pudding" composed of electrons embedded in diffuse positively charged matter, as shown on the right.