Lorenzo Romano Amedeo Carlo Avogadro Contedi Quaregnaedi Cerreto was born to a highly placed family, in Turin, the capital of the Piedmont region of Italy. He attended school in Turin, after which he obtained degrees in law. Although Avogadro had a successful legal career, he took private lessons in mathematics and sciences,including chemistry. He taught the natural sciencesand went on to hold the Chair of Physics at theUniversity of Turin for much of his career.
In 1811, Avogadro published an article in Journal de physique that clarified the distinction between molecules and atoms. He hypothesised that ‘Equal volumes of all gases at the same temperature and pressure contain the same number of molecules’. Although not generally accepted at the time, his hypothesis has now become a well established law in chemistry.
Based on Avogadro’s work and that of other scientists, French Physicist, Jean Perrin defined the number of atoms or molecules which make up a mole of a substanceas 6.02214179×1023 mol-1. He named this Avogadro’s Constant.