Rutherford’s Gold Foil Experiment

Ernst Rutherford conducted the Gold Foil experiment to prove the assumptions made by JJ Thompson and thereby propose a model for the structure of the Atom.

But the results were contrary to his expectations.





Uses of the various equipments in the apparatus:

Alpha Particles: These are dipositive Helium atoms, to be clear Helium atoms whose both the electrons have been snatched away, this makes it highly unstable and can cause you cancer by destroying your genetic matter.  You would not want it in your bookshelf, or would you?

Lead Box: The only substance dense enough yet cheap, that can stop α-particles from going helter-skelter. FYI: It’s poisonous, not to be consumed.

Gold Foil: Gold is the really heavy element and comparatively cheap and stable with respect to other heavy, solid metals. A heavy element is ideal as it has a bigger nucleus.

ZnS Screen: Zinc Sulphide is a phosphorescent material and creates sparks when it comes in contact with highly charged particles (here α-particles). It helps to observe the result of the experiment.

Charged Poles: Since the α-particles are positive the positively charged poles help to concentrate and fire the α-particles in a straight path by repelling it from every direction. (I suppose you get my point)



  • Rutherford based his idea on Thomson’s and had assumed that most of the α-particles would pass right through the foil without much disturbance.
  • The contents of an atom are evenly spread.



Observation and Results


  • Most of the α-particles went straight through the foil but a few of them did deflect and 1 in 12,000 completely reflected back, this implies that the contents of an atom is not evenly spread and,
  • The positive part of the atom is concentrated in the centre and there is a lot of empty space around it.
  • Thus the model was named as planetary model



Rutherford’s Model Of Atom

Atomic Model of Bohr is available in detail in next chapter.


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