From 6:02 in the morning until 6:02 in the evening on 10/23, many scientists celebrate the unofficial holiday National Mole Day. The Mole is a standard international unit of measure, and refers to the amount of a substance that has exactly 6.02 x 10²³ particles in it. This number was derived by Amedeo Avogadro in the early 1800’s and its significance lies in the fact that one mole of atoms of an element will weigh exactly the atomic weight of that element when expressed in grams. For example, 6.02 x 10²³ atoms of hydrogen will weigh exactly 1.01 g, while 6.02 x 10²³ atoms of oxygen will weigh exactly 16 g.

The idea of celebrating a National Mole Day was first proposed in the early 1980’s in an article  written by a teacher in the journal The Science Teacher. Then, in 1991, Maurice Oehler, a High School chemistry teacher, established the National Mole Day Foundation as a way of promoting the idea. The unofficial holiday has grown into a national educational celebration, in which activities and events are held across the country and even around the world as a way to increase interest in and understanding of science and chemistry.

To learn more about the Mole, visit our module: The Mole: Its History and Use.

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