Monday, October 4, 2010

Rutherford's Gold Foil Experiment

Have you ever wanted to prove your teacher wrong?  This was actually NOT the intention of Ernest Rutherford when he accidentally proved his teacher and mentor wrong.  Rutherford, a New Zealand native, had spent many a year as a student of J.J. Thomson and fully believed his "plum pudding" theory about the atomic structure.  In this theory, all particles in the atom were evenly distributed like plum pudding.  The image below shows this diagram.
To prove his teachers theory, Rutherford set up an experiment.  First, he set up a source of alpha particles that emitted them in a beam.  Rutherford also discovered these alpha particles which are basically high speed, positively charged, helium nuclie.  He then shot these particles at a thin piece of gold foil which was surrounded by Fluorescent screen that would detect the alpha particles.  The set up looked something like this.

What Rutherford expected, and what would prove Thomson's theory would be the alpha particles passing through the gold foil (made up of plum pudding molecules right? phhhht! noooo) with little or no    reflections.  What he discovered, however, was that the positively charged alpha particles would every so often hit something in the gold foil that made them bounce in huge reflections!  What they were hitting is the positively charged nucleus of the atoms in the foil.  To understand this more try this interactive activity on this link.  Watch how the more alpha particles that are introduced, the more are reflected from the nuclei.
Interactive Activity
You may be asking yourself, "Why does this matter?"  This is actually one of the most important moments in the history of SCIENCE!  This is the event that caused Rutherford to come up with a new model for the atom.  Without the gold foil experiment we might still be thinking we're connected by plum pudding like atoms.  Rutherford is the father of the modern atomic structure and this experiment helped start it all.
by: Paxton Swisher
Works Cited 
“About Rutherford’s Gold Foil Experiment.” eHow. N.p., n.d. Web. 3 Oct. 2010. <‌about_4569065_rutherfords-gold-foil-experiment.html>.
The Encyclopedia of Science. N.p., n.d. Web. 3 Oct. 2010. <‌encyclopedia/‌R/‌Rutherfords_experiment_and_atomic_model.html>.
kem korner. N.p., n.d. Web. 3 Oct. 2010. <‌2010/‌07/‌rutherfords-gold-foil-experiment.html>.
Molecular Expressions. N.p., n.d. Web. 3 Oct. 2010. <‌electromag/‌java/‌rutherford/>.
reich-chemistry. N.p., n.d. Web. 3 Oct. 2010. <‌stephen.gasecki.timothy.graham.atomichistory.fall.2009>.