As part of their third-year general chemistry program, students at the University of the Côte d'Azur are taught the basics of radioactivity. The view that third-year university students have of the periodic Table of the Elements is often reduced because it ignores the vast majority of isotopes. As part of this program, a practicum devoted to the observation of a and b particles has been put in place and a table-top version of a cloud chamber of the Langsdorf type was designed, but in its simpler, static version. With a simple experiment and a source of natural uranium, concepts that normally belong to the distinct disciplines of thermodynamics, classical point physics, nuclear instability and even chemistry are being addressed in a complementary manner. This article gives a full description of the various concepts that may be taught during the practicum, together with the basic equations. Numerical applications performed with observed data are proposed and discussed together with tabulated data. Through this practicum, students can actually observe radioactivity directly and come to understand that nuclides may be stable or unstable.of discoveries that followed -the identification of α and β radiations by E. Rutherford (which later allowed him to model the structure of the atom, giving rise to the representation further proposed by N. Bohr), the discovery of spontaneous transmutation by E. Rutherford and F. Soddy (who later showed the existence of isotopes), the identification of the neutron by J. Chadwick, the discovery of artificial radioactive isotopes and transmutation by I. and F. Joliot-Curie, and the discovery of fission in 1938 by L. Meitner and O. Hahn (L. Meitner was never recognized for her role in the discovery) -is the high point of this unique adventure. 3,4 It was in the context of this intense scientific research that the stage was set for the discovery of the cloud chamber, a new experimental tool used for detecting ionizing particles and for determining their trajectories. At the Cavendish laboratory of Cambridge University (created in 1874 under the Direction of J. C. Maxwell) early in 1911, C. T. Wilson first produced photographs of the tracks of individual a and b particles using a new experimental tool called a cloud chamber : "On a method of making visible the paths of ionizing particles through a gas". 5 These can include any electrically charged particle that passes through the chamber. With this device, the number of ionization events could be deduced from the number of tracks in the chamber and could be used to determine the particle's properties. But it was not until 1923 that the cloud chamber was further optimized, leading C. T. Wilson to publish his first paper on the tracks of electrons. 6,7 He was awarded the Nobel prize in physics in 1927 "for his method of making the paths of electrically charged particles visible by condensation of vapour". 2 At the beginning of this same decade, in 1920, E. Rutherford pursued his exploration of the structure of the atom that led to the discove...
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