Radioactivity - Radioactivity

Radioactivity - a bit of history

The Structure of the Atom

The basic structure of the atom must be understood before radioactivity can be tackled. A historical investigation as to how we developed our ideas on its structure should begin with JJ Thompson's 'plum pudding' and work through to Rutherford's deductions after the alpha scattering experiments.

The nucleus of the atom is made up of protons and neutrons. You may think that the nucleus should not exist at all because the protons are all of the same charge and would want to fly apart! However they are held together by a very strong force indeed called the strong nuclear force. This is a hundred times stronger than the repulsive force due to charge. Some nuclei are not 'happy with' their state. They need to emit nuclear radiation to get to a more stable state. That is why nuclei 'decay' and emit radioactive particles. Click here to find out more detail.

History Links

http://guinan.gsfc.nasa.gov/docs/heasarc/headates/heahistory.html	This link has a useful timeline - look in the 1800-1900 section
http://www.atomicrocks.com/index3.htm	This contains a useful account of the discovery of nuclear radiation
http://www.dbhs.wvusd.k12.ca.us/radioactivity/Disc-of-Alpha-Scatter.html	Look at Rutherford's work on the model of the atom
http://www.treasure-troves.com/bios/Rutherford.html	More background on Rutherford is found here.