. WRITE THE POSTULATES OF RUTHERFORD ATOMIC MODEL
On the basis of the above observation, and having realized that the rebounding -particles had met something even more massive than themselves inside the gold atom, Rutherford proposed an atomic model as follows.
1. All the protons (+ve charge) and the neutrons (neutral charge) i.e nearly the total mass of an atom is present in a very small region at the centre of the atom. The atom’s central core is called nucleus.
2. The size of the nucleus is very small in comparison to the size of the atom. Diameter of the nucleus is about 10–13cm while the atom has a diameter of the order of 10–8 cm. So, the size of atom is 105 times more than that of nucleus.
3. Most of the space outside the nucleus is empty.
4. The electrons, equal in number to the net nuclear positive charge, revolve around the nucleus with fast speed in various circular orbits.
5. The centrifugal force arising due to the fast speed of an electron balances the coulombic force of attraction of the nucleus and the electron remains stable in its path. Thus according to him atom consists of two parts (A) nucleus and (B) extra nuclear part.