Scattering To Determine Structure

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Alpha particle scattering lets us see into the atom.  If a beam of positively charged alpha particles is directed at a thin, gold film, most pass straight through.  However if an alpha particle is travelling straight towards, or close by, a nucleus, it's path will be deflected.  Experimental evidence shows that some of these alpha particles are deflected by more than 90 degrees - they bounce back.  This evidence means that inside the atoms there must be small positively charged nuclei, which repel the passing alpha particles.  The nucleus must be small since very few alpha particles are deflected by much.  It must be positive to repel the positively charged alpha particles.You can estimate the closest approach of a scattered particle.  When you fire an alpha particle at a gold nuclues, you know it's initial kinetic energy.  An alpha particle that 'bounces…





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