National Mole Day is celebrated annually on October 23 from 6:02 a.m. to 6:02 p.m. It celebrates Avogadro’s Number (6.02 x 1023), which is a basic measuring unit in chemistry. National Mole Day was created as a way to foster interest in chemistry, and schools throughout the United States and around the world celebrate with various activities related to chemistry and/or moles.