Chemistry Rutherford atomic model full explanation class 11,12and note copy pdf

 

Rutherford Atomic Model

This model was put forward by emest Rutherford in 1911 with help og du particle scatering experiment: Io this experiment, bombarded thin sheet of gold foil (0.0004 cm thickness) with (alpha particle ) positive particles equivalent to helium ion , He²+ which were obtained from a radioactive substance. The scattered alpha particles were observed on the surface of a circular zinc sulphide screen as they produce tiny flashes

with a help of movable microscope as follows:

a) Most of the a-particles passed etreoight

through the gold joll undeglected.

b) Some of the a- particles deflected through small

angles.

c) Few of the in particles were reflected or returned back (about lin 20,000).

   🔴On the basis of above observation, it can concluded that

a) since most of the Alpha particles of

passed straight through the gold foil undeflected, it indicates the most of space inside the atom is empty.

B. The cause of deflection of Alpha particles through

small angles is due to the presence of

heavy positively charged body at the centre

of the atom.

C. The volume occupled by the

Centre of the atom (radius of centre in the order of 10-¹³ cm) is 

very small compared To the total volume of the atom

(radius of the atom in the order of 10-⁸ cm) That is why very few rays are reflected back

due to the close encounter with the centre of the atom or it can be said that whole mass of the atom is concentrated the nucleus . 

🔴 Based upon the above conclusion , Rutherford put forward the following postulate

🔴 Drawbacks of Rutherford's atomic model

1. He couldn't explain about the stability of atoms.

2. He couldn't describe about the origin of hydrogen spectrum .