Transcript The gold Foil experiment - ency

( 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 , freefloating ,negatively charged particles called
electons .

But In 1910 , Rutherford tested Thomson’s
theory by using « Gold Foil experiment ».
He suggested that the plum puudding
model was incorrect.
An extremely thin gold foil is bombarded with the
narrow 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.
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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 .
- 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 .
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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