Mole Day is an unofficial holiday celebrated among chemists in North America on October 23, between 6:02 AM and 6:02 PM, making the date 6:02 10/23 in the American way of writing out dates. The time and date are derived from Avogadro's number, which is approximately 6.02×10²³, defining the number of particles (atoms or molecule) in a mole, one of the seven basic SI units.

Many high schools around the United States and in Canada celebrate Mole Day as a way to get their students interested in chemistry.

Celebrated annually on October 23 from 6:02 a.m. to 6:02 p.m., Mole Day commemorates Avogadro's Number (6.02 x 10^23), which is a basic measuring unit in chemistry. Mole Day was created as a way to foster interest in chemistry. Schools throughout the United States and around the world celebrate Mole Day with various activities related to chemistry and/or moles. For a given molecule, one mole is a mass (in grams) whose number is equal to the atomic mass of the molecule. For example, the water molecule has an atomic mass of 18, therefore one mole of water weighs 18 grams. An atom of neon has an atomic mass of 20, therefore one mole of neon weighs 20 grams. In general, one mole of any substance contains Avogadro's Number of molecules or atoms of that substance. This relationship was first discovered by Amedeo Avogadro (1776-1858) and he received credit for this after his death.

The 2006 theme will be mole madness. - the mole day foundation web site.

See also

• Pi Day

Geek holidays

Journée de Mole | 몰의 날 | Giorno della mole | Mólnap | 摩尔日