Alpha ray scattering experiment

In summary, Rutherford and his students conducted an alpha ray scattering experiment in 1909 to determine the structure of an atom. They measured the velocity of the alpha particles and the charge of the gold nucleus in order to calculate the distance of the closest approach. They also knew the charge on the gold nucleus was 79, but it is unclear if they were aware of the atomic number of gold at the time. They were able to determine the exact radius of the gold nucleus by observing the different distances at which alpha particles with different velocities came to a stop in front of the gold foil. Further experiments and discoveries served to strengthen the model of the atom as a dense nucleus and a relatively high volume of non-matter, as opposed to Thomson's
  • #1
ananthu
106
1
I have some basic doubts in the alpha ray scattering experiment by Rutherford and his students way back in 1909.

1.In the formula for the distance of the closest approach, the term velocity of the alpha particle and the charge of the gold nucleus appears. How did they measure the velocity of the alpha particle?

2. How did they know that the charge on the gold nucleus was 79? In 1909 were they aware of the atomic number of gold? If yes, by what means?

3. The alpha particles with different velocities will come to stop at different distances in front of gold foil. Then how did they know the exact radius of the gold nucleus?

Though there are some attempts to answer these questions in certain textbooks they are too complex to understand.
 
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  • #2
As this is my first post, not sure if I should have started a new thread, but I also want to know,
How did they measure the velocity of the alpha particle?[/QUOTE said:
Also, I understand that this offers a model of the atom as we have today of a dense nucleus and a relatively high volume of nonmatter, and that further experiments and discoveries probably served to strengthen this model as opposed to Thompson's plum pudding model. Could someone please provide references of such strengthening so that I may better understand its applicability?

For example, from my common macro-level experience, I can imagine an alternative deduction from the experiment as a pool ball collision in billiards. The movement of the white ball (analogous to the alpha particle) after hitting another pool ball (analogous to the gold atom) is dependent on what kind of spin you hit the white ball with. Therefore, why couldn’t the decay of the radon be such that the scattering of the alpha particle is dependent upon the random (in being uncontrolled and immeasurable) spin in which it leaves from the radioactive source. Such a possibility seems to uphold Thompson's model as possible.
"Bob_for_short" posted at the end of another thread, that there is "a strong Z- and M_a dependence." Assuming this is true, then the Thompson model seems less attractive to me unless maybe some type of nuclear interaction occurs between the gold atom and the alpha particle relative to the nuclear spin of the gold atom, which also is a factor in the degree of scattering of the alpha particle. From my knowledge, this can be consistent with the fact that the degree of scattering has a strong dependence on Z- and M_a (which I assume to be the atomic number and atomic mass, right?) as that nuclear spin may in turn be effected by these variables.

I do recognize I am going out of my way to find an alternative explanation, and again I would be glad to go through references that would strengthen the divergence of the theory of matter as phenomenalized by this experiment's deductions.

References that reveal falsifiability criteria of atomic level modeling (even currently) are also appreciated.
 

1. What is the purpose of the Alpha ray scattering experiment?

The purpose of the Alpha ray scattering experiment is to study the structure of an atom by bombarding a thin gold foil with alpha particles and observing the scattering pattern of the particles.

2. How is the Alpha ray scattering experiment conducted?

The experiment involves a source of alpha particles, typically a radioactive substance, and a thin gold foil. The alpha particles are directed towards the gold foil and the resulting scattering pattern is observed on a detector.

3. What does the scattering pattern of alpha particles in the experiment indicate?

The scattering pattern indicates the presence of a small, dense nucleus in the atom, as most of the alpha particles pass through the foil without any deflection, but a small percentage are deflected or even bounce back.

4. What information can be obtained from the Alpha ray scattering experiment?

The experiment can provide information about the size and structure of the nucleus, the number of protons and neutrons in the nucleus, and the overall size of the atom.

5. What are some limitations of the Alpha ray scattering experiment?

Some limitations of the experiment include the inability to observe smaller particles within the nucleus, such as quarks, and the fact that it does not account for the electron cloud surrounding the nucleus.

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