CHEMISTRY IN SPACE

Molecules have been observed in widely disparate astronomical objects, from comets to supernova remnants. Interstellar space appear to be a real chemical laboratory, able to produce a large number of molecules, some of them relatively complex. The abundances show a very high sens itivity to local physical properties and dynamical history. This sensi tivity renders molecular observations and astrochemical modelling very flexible tools for investigating the properties and evolution of the interstellar medium. A brief outline of morfology of interstellar medi um is given, together with a discussion of the basic chemical processe s leading to the molecular formation. Since interstellar-dust particle s play a crucial role in the chemical evolution of interstellar medium , physical and chemical properties of dust are reviewed. Finally, by w ay of an example of modelling exercise, a toy model of the chemical ev olution of interstellar gas is presented.