Level: introductory
Reference: Ernest Rutherford, "Collisions of alpha Particles with Light Atoms. IV. An Anomalous Effect in Nitrogen," The London, Edinburgh and Dublin Philosophical Magazine and Journal of Science, 6th series, 37, 581ff (1919).
Notes: Ernest Rutherford (1871-1937) made many fundamental discoveries in nuclear science, including discovery of the nucleus itself. Before that, he distinguished two kinds of radioactivity (imaginatively named alpha and beta); with Frederick Soddy he realized that radioactive decay involved transformation of chemical elements into other elements; and he introduced the concept of radioactive half life. He was awarded the Nobel Prize in chemistry (yes, chemistry) in 1908.
In the paper on which this exercise is based, Rutherford detected the hydrogen atom fragment. He also knew that the alpha particle was an ordinary helium nucleus. The neutron had not yet been discovered, though, so nuclear composition in terms of protons and neutrons was not then known. In fact, Rutherford does not even tentatively identify the element produced other than hydrogen. To me, the discussion section of his paper suggests that he envisioned something like the reaction described in part (a) of the exercise. That is, it reads as if the alpha particle acted as a projectile that chipped a piece from the nitrogen nucleus. The reaction really goes as in part (b), though.
Solutions: To download solutions, go to:
http://webserver.lemoyne.edu/faculty/giunta/classicalcs/rutherart.doc
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