THE GOLD FOIL EXPERIMENT ( Rutherford’s experiment )

Before 1910 , the structure of the atom was thought to correspond with the « plum pudding model » . In summary , the Plum pudding model was hypothesized by J.J Thomson ( the discovrer of the electron) who described an atom as being a large positively charged body that contained small , free-floating ,negatively charged particles called electons .

introduction

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But In 1910 , Rutherford tested Thomson’s theory by using « Gold Foil experiment ».

He suggested that the plum puudding model was incorrect.

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An extremely thin gold foil is bombarded with thenarrow beam of fast moving Alpha particles (alpha particles are fast moving packet of hilium).On bombarding,the alpha particles are scattered in different directions with different angles and are detected by a detector which has a screen coated with Zinc sulphat.

Rutherford’s experiment

- Almost all the alpha particles pass throw the foil.- Some alpha particles are deflected at

different angles . - Few of the Alpha particles bounced

backward after hitting the gold foil .

Observation

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- If some Alpha particles approach some positively charged region , they are deflected by large angle or bounced backward .

- If there is a lot or space in the atom , the most Alpha particles pass straight throught the gold foil without any deflection .

Conclusion

So in general , we conclude that the most of the space within the atoms in empty and the volume occupied by the positive charges is very small . In another way we can say that in the central region of the atom , the positively charged particles are present and the negatively charged particles «electrons » revolve around the central positive portion.

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Rutherford’s model

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Later on the basis of this theory further imrovements were made in the structure of the atom by Neil Bohr who will prove that electrons are fixed on orbits.