It was thought that the alpha particles would pass straight through the thin foil, or possibly puncture it. The scientists were very surprised when other things happened:.
Rutherford was astonished by these results. Why was Rutherford's gold foil experiment important? What did Rutherford's gold-foil experiment tell about the atom?
Who described the Plum Pudding model? What did Rutherford's gold foil experiment demonstrate? How does the kinetic energy of the alpha particles affect the angle of deflection? How could they find out? Marsden did not think that Rutherford was really expecting any results, but went along with the hunch anyway and built a small piece of equipment that would provide an answer.
It is shown in the figure below. A source of alpha particles is hidden behind a lead screen so that the rays cannot impact directly on the scintillation screen and be observed. Then a piece of gold foil is placed in the chamber in such a way that any reflected alpha rays bounce back and can be seen flashing on the scintillation screen.
With no gold foil in place, nothing was seen on the screen, but when the foil was inserted Geiger reported to Rutherford in great excitement that " We have been able to get some of the alpha particles coming backwards! It was an unexpected and very important discovery, which Rutherford started to think about. What did it mean? About 1 in 20, alpha particles shot at a thin foil of gold were reflected back just as light does when falling on a mirror. Marsden and Geiger tested other metals, and got the following results:.
By December 14th, , in a letter to B. Boltwood, Rutherford had sorted though a number of possible explanations for these "reflections" of alpha particles, and wrote that he was " His thoughts were also beginning to come together. On consideration, I realized that this scattering backward must be the result of a single collision, and when I made calculations I saw that it was impossible to get anything of that order of magnitude unless you took a system in which the greater part of the mass of the atom was concentrated in a minute nucleus.
It was then that I had the idea of an atom with a minute massive centre, carrying a charge. Thus, nuclei are simply very small, but very dense, as stated by Enigma and Ilmari Karonen. The simple reason for this being the ratio of masses of alpha particles and electrons Both experience equal electrostatic forces which leaves no option for the electron but to get displaced from its current position it gains potential energy to do so whereas in the case of alpha-nucleus interaction,the size of a nucleus is comparable in the case of the gold foil he used Hopefully you got your answer.
I was also wondering upon the fact that it could be the electrons which caused the sway, but you see if a certain force were acting on two particles, one lighter than the other, the lighter one will be the one feeling the "force".
For more clarity refer to Newtons second law in acceleration format. Hope it resolves your issue. Well gentlemen we can't deny that fact that there might be some forces of attraction between the alpha particles as well as the electrons,because the alpha particles passed through the atom by small distance margin from nucleus and stroked the zinc sulphide coating but it wasn't clearly stated by Ernest Rutherford that whether the deflection was also caused due to alpha particle attraction and election attraction.
Also, attraction interaction is between comparable things like a heavy nucleus and heavy alpha particle but it's silly to think about alpha particle and an electron , the alpha particle is approximately times heavier than electron and it is travelling with a high speed energy so we can say that the interaction time might be very much less in order to show its effect and we can underestimate it.
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