According to the law of electro-dynamics, the electron should therefore, continuously emit or use energy for moving and get closer to the nucleus and after passing through a spiral path, ultimately fall into the nucleus. Stability of the Atom: Neils Bohr pointed out that Rutherford’s model of atom is defective. Position of electrons: The exact positions of the electrons from the nucleus are not mentioned.Ģ. 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.ġ. The electrons (equal in number to the net nuclear positive charge) revolve around the nucleus with fast speed in various circular orbits. Most of the space outside the nucleus is empty. So, the size of atom is 10 5 times more than that of nucleus. Diameter of the nucleus is about 10 -13 cm while the atom has a diameter of the order of 10 − 8 cm. The size of the nucleus is very small in comparison to the size of the atom. The atom’s central core is called nucleus. nearly the total mass of an atom is present in very small region at the centre of the atom. On the basis of the above observations, Rutherford proposed an atomic model as followsĪtom consists of two parts: (a) nucleus and (b) extra nuclear part.Īll the protons (+ve charge) and the neutrons (neutral charge) i.e. Some α-particles were even scattered in the opposite direction at an angle of 180°. Very few α-particles are deflected backwards through angles greater than 90°. Some α-particles are deflected from their path and diverge. Majority of the α-particles pass straight through the gold strips with little or no deflection. The zinc sulphide screen gives off a visible flash of light when struck by an α particle, as ZnS has the remarkable property of converting kinetic energy of α particle into visible light. Rutherford allowed a narrow beam of α-particles to fall on a very thin gold foil of thickness of the order of 0.0004 cm and determined the subsequent path of these particles with the help of a zinc sulphide fluorescent screen.
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