Mole Day
October 23, Thursday
History of the holiday
Mole Day appeared in the 1980s through the initiative of American chemistry teachers. The idea belongs to Maurice Oehler, a chemistry teacher from Wisconsin, who proposed celebrating this day to increase students’ interest in chemistry.
The date was chosen deliberately — October 23 (10/23 in the American format) from 6:02 a.m. to 6:02 p.m., symbolically referencing Avogadro's number: 6.022 × 10²³ — the number of particles in one mole of substance.
Significance of the holiday
The mole is a unit for measuring the amount of substance, used in the International System of Units (SI). It links the microscopic world of atoms and molecules with the macroscopic world of measurable substances. Mole Day helps make the study of chemistry more engaging and understandable, reminding us how fundamental scientific principles underlie everyday phenomena.
How the holiday is celebrated
On this day, schools, universities, and laboratories hold themed events:
* quizzes and competitions on chemistry knowledge;
* demonstrations of chemical experiments;
* creating costumes and decorations related to Avogadro's number and molecules;
* baking "mole" cakes and cookies with chemical symbols;
* lectures and popular science presentations explaining the importance of the mole in science.
Interesting fact
In the USA, there is an organization called the Mole Day Foundation, which coordinates the celebration and annually proposes a new theme for Mole Day. Popular slogans in past years included, for example, "Molar Eclipse" and "The Mole the Merrier."
Mole Day in other years
- 2021 October 23, Saturday
- 2022 October 23, Sunday
- 2023 October 23, Monday
- 2024 October 23, Wednesday
- 2026 October 23, Friday