Xenon, Helium, Neon, Argon, Krypton and the radioactive Radon belong to the noble gases. These form the family of noble gases as the elements of the eighth group of the periodic table. All of them are colourless and odourless, non-inflammable and non-toxic. Their most striking chemical property is their inertness. This can be explained by their electron arrangement, termed noble gas configuration and represents a particularly stable and therefore low-energy state. The noble gases are to be found in scant amounts in our air from which they are also distilled. Helium is mainly extracted from natural gas. In everyday life, we encounter noble gases for example as shielding, filling or buoyant gases and in fluorescent tubes. The shell model describes the structure of the atoms. It is based on the distribution of electrons in restricted areas at a fixed distance around the core of the atom.