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From Rutherfords alpha scattering, where alpha where fired at a thin peace of metal foil, he concluded that the nuclie was positivly charged. He made this conclution from the fact that alpha particles where scattered at different angles but would a negative charge not scatter the alpha the same way as a positive. As far as i can see it the scattering pattern caused by alpha been deflected of there path by an attractive force would be the same as a replusive. So why did he conclude the nuclous was positivly charged??

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The Geiger–Marsden experiment was performed in 1909, 12 years after the electron was identified as particle. It was already known that electron is negative and thousand times lighter than the lightest atom - hydrogen. Electrons could not scatter the alpha particles because the alpha particle is thousands of times heavier than the electron so the alpha particle would just go through. Something comparably heavy has to scatter the alpha particle and this something has to have charge of opposite sign than the electrons have for the atom to be neutral.

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Electrons certainly scatter off of alpha particles, and follow Rutherford cross sections as well. They just take very little energy, as you correctly state. As @Joseph states, either an attractive or repulsive force can cause the scattering (consider a comet and the sun with gravity a purely attractive force). They knew of the electron, knew it was part of the atom, and were looking for where the positive charge was. The observed scattering events were few in number, and large in energy transferred, pointing towards a small number of heavy scatterers, rather than the plum pudding model. – Jon Custer May 2 '14 at 19:05

The reason he concluded that it was a positive nucleus was because the alpha particles, a very small fraction of them got deflected directly back where they came from (or to be precise, angles greater than 90 degrees). This could not have been caused by electrons as they were big enough for the fraction to be significantly higher, plus he already proved that alpha particles where positively charged (+2), even though he didn't know it was actually itself a nucleus. So only a massive but small positive charge concentrated in a region could have caused this big deflection.

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