The nucleus of an atom is dense and positively charged. what was observed when positively charged particles were radiated onto a gold atom during rutherford's experiment because of this? negative charges were concentrated at the center of the atom. particles that struck the center of the atom were repelled. particles that struck the edges of the atom were repelled. positive charges were distributed all over the atom.

Particles that struck the center of the atom were repelled.

Explanation:

In 1911, New Zealand physicist Ernest Rutherford carried out an experiment in order to deepen his knowledge of the atomic model hitherto adopted, which was that of Thomson; in which the atom would be a sphere of positive, non-massive electrical charge, encrusted with (negative) electrons, so that its total electrical charge would be zero.

To carry out such an experiment he bombed a very thin gold leaf (thickness of approximately 10-4 mm), through a beam of alpha particles (α), coming from a sample of polonium. The polonium was inside a lead block, with an orifice, through which only the emissions of alpha particles would be allowed out.

In addition, lead plates with holes were placed in their centers, which would orient the beam towards the gold blade. And, finally, a bulkhead covered with zinc sulfide, which is a fluorescent substance, was placed behind the slide, where it was possible to visualize the path taken by the alpha particles.

At the end of this experiment, Rutherford noticed that most of the alpha particles passed through the slide, did not deflect or retreat. Some alpha particles deflected, and very few receded. In addition, the particles that reached the center of the atom were repelled.

Based on these data, Rutherford concluded that, contrary to what Dalton thought, the atom could not be massive. But in reality, much of the atom would be empty and it would contain a very small, dense and positive nucleus.