The University of Iowa Sciences Library would like to wish you a Happy Mole Day!

Mole Day is traditionally observed by admirers of chemistry worldwide on October 23^rd, from 6:02am to 6:02pm.  The purpose of the day is to generate enthusiasm and interest in chemistry, and to commemorate the discovery of Avogadro’s Number, which is approximately 6.02 x 10^23. ¹

Amadeo Avogadro (1776-1858) was an Italian physicist whose hypotheses contributed to the discovery of the ideal gas law, and is credited with discovering the mole, which is a basic measuring unit in chemistry.  One mole of a substance contains Avogadro’s number of molecules or atoms of that substance. ¹

Avogadro’s ideas were largely unrecognized during his lifetime.  They became more well-known after his death when Stanislao Cannizzaro argued for their acceptance in 1860. ²