Problem: Rutherfords alpha-scattering experiment. When alpha particles pass through a gold foil, most pass through undeflected but some are scattered, a few at very large angles. According to the plum-pudding model of the atom, the particles should experience only very minor deflections. The nuclear model of the atom explains why a few alpha particles are deflected at large angles. Although the nuclear atom has been depicted here as a yellow sphere, it is important to realize that most of the space around the nucleus contains only the low-mass electrons.Will they be attracted to or repelled from the positively charged gold nuclei?

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opposite charge → attract

similar charge → repel


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Problem Details

Rutherfords -scattering experiment. When particles pass through a gold foil, most pass through undeflected but some are scattered, a few at very large angles. According to the plum-pudding model of the atom, the particles should experience only very minor deflections. The nuclear model of the atom explains why a few particles are deflected at large angles. Although the nuclear atom has been depicted here as a yellow sphere, it is important to realize that most of the space around the nucleus contains only the low-mass electrons.

During an experiment, a beam of particles from a source of alpha particles is passed through an opening in a circular fluorescent screen. The beam strikes a piece of gold foil in the center of the circular screen and is split. Most of the alpha particles undergo little to no scattering because most of the atom is empty, and so the beams strike the screen at small angles behind the gold foil. The interpretation is that as incoming particles pass through the foil, they pass in a straight line because most will miss the t0iny nucleus and pass through the large areas of empty space of the atom. A tiny fraction of the alpha particles are scattered at large angles because their path takes them very close to an extremely small but highly charged nucleus. These beams strike the screen at large angles from the foil The interpretation is that an incoming alpha particle is only bent at a large angle when it strikes a tiny nucleus.


Will they be attracted to or repelled from the positively charged gold nuclei?

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