What are the conclusions of Gold foil Experiment?

Gold foil Experiment and conclusions:

Helium Ions (α-particles) from a radioactive material (Radium) is passed through narrow slits to collimate them into straight-line path. Fast moving α-particles are made to hit a thin sheet (foil) of gold metal of about 100nm thickness. A photographic film or a screen coated with fluorescent- zinc sulphide material, is kept around the gold foil. Number and the angle of deflection of the scattered α-particles all around the gold foil, is measured by their interaction, with the film.

From the location and number of α-particles reaching the screen, Rutherford concluded the following:

i) Almost 99% of the α-particles pass through the gold foil without any deflection.

So atom must be having a lot of empty space in it.

ii) Several α-particles get deflected at angles.

α-particles being positive, the deflection can be caused only by the presence of another positively charged particle inside the atom.

iii) A few α-particles (one in twenty thousand) do not either go through or get deflected by the atom, rather they bounces back.

A heavy and highly positively charged particle must then have opposed these, few α- particles

in the atom. A higher charge density indicate a smaller size. Rutherford considered this smaller sized positive charged part as a dense core and called it as nucleus. Nucleus contains all the protons present in the atom and hence the mass of the atom.

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