Atomic Model of Rutherford – Structure of Atom

Atomic Model of Rutherford

  In 1911, Lord Rutherford made an experiment to construct an atomic model. He took a thin gold foil and bombarded it with α-particles. Gold foil was surrounded by photographic film.

Rutherford’s Observations:

He observed in the alpha scattering experiment that :

  • Most α-rays passed through gold foil un-deflected.                                                                                               
  • Only a few were deflected at an angle greater than 90o.                                                         
  • Very few were bounced (i.e. turned back).                                             

Rutherford Experiment Conclusions :

On the bases of these alpha scattering experiment observations, Rutherford made the following conclusions.

  • As the majority of α-rays passed un-deflected so most of the atomic volume is empty space.
  • As only a few α-rays deflected from their straight path so some positive portion is there in the atom which has repelled +ve α-rays. This portion is very small in size so occasionally it comes in front of some α-rays.
  • As very few α-rays were bounced so some massive portion is there in the atom which has pushed back the α-rays. This portion is very small in size so occasionally it comes in front of some α-rays.

This heavy and positive portion is given the name “Nucleus” by Rutherford.

  • All the mass of the atom concentrates in the nucleus.
  • The atomic system resembles a solar system in which the nucleus is like the sun and electrons are like planets. Electrons are revolving around the nucleus as planets around the sun.
  • The number of protons and electrons is equal so the overall atom is neutral.
Atomic Model of Rutherford scattering of alpha particles
Rutherford’s Alpha Scattering Experiment

Defects of Rutherford Model:

   The following defects were pointed out in Rutherford’s atomic model

structure of atom diagram
  • According to Rutherford, the atom resembles a solar system so laws of gravitation should be applicable to it but these laws do not apply to the atom as it consists of charged particles.
  • According to Maxwell’s classical electromagnetic theory, if a charged particle revolves around an opposite charge particle it radiates continuous energy. And if it is so then the electron should fall into the nucleus following a spiral path and the atom should collapse. But it does not happen in atoms.
  • If electrons emit continuous energy then the atomic spectrum should be continuous but it is a line spectrum.
  • There were no defined orbits for electrons.  

Recommended video

Check out free notes !!

-> Class 10 Chemistry Full book pdf

-> Class 11 Chemistry Full book pdf

-> Class 12 Chemistry Full book pdf

For joining best Chemistry Coaching

Leave a Reply

%d bloggers like this: