National Mole Day - October 23
Mon, Oct 23, 2023

National Mole Day

National Mole Day is celebrated on October 23 around the world. It is not about an animal burrowing underground, but is instead a commemoration of a basic chemical algorithm, known as Avogadro’s Number. That said, if you’d like, you can celebrate a double holiday!


National Mole Day has its origins in 1980, when an article in The Science Teacher inspired a teacher from Prairie du Chien High School to create an official holiday. Initially, it was celebrated in May, but was then moved to October. In 1991, the National Mole Day Foundation (NMDF) was created to commemorate the day. Celebrations take place from 6:02 to 18:02, as these numbers are derived from Avogadro’s Number (approximately 6,02×10^23). This number is the result of a hypothesis formulated by chemist Amadeo Avogadro, who stated that equal volumes of different gases contain the same number of molecules. Avogadro was born in 1776, and although he was only recognized for his work 50 years after his death, he is now considered one of the founders of physical chemistry.

Interesting facts

  • The impulse to active experiments for Avogadro was the discovery of Gay-Lussac’s gas laws.
  • A crater on the moon is named after the chemist.
  • Avogadro’s scientific activity began with the study of electrical phenomena.
  • Initially, his hypothesis was rejected by most chemists, as it did not correspond to experimental data.

How to take part

The best way to celebrate Mole Day is to fall in love with chemistry! This is an amazing, spectacular, and beautiful science, and if you understand its essence, you will find it easy to get lost in it. Consider teaching children about the law and its essence, or showing examples. You can also test your knowledge of chemistry by taking tests available on the internet. Another option is to buy a white T-shirt and print Avogadro’s Number on it – this will surely attract passersby to the holiday. Consider also finding and meeting other chemists of this era.

When is National Mole Day celebrated in 2023?

National Mole Day is observed on October 23 each year.


Weekday Month Day Year
Monday October 23 2023
Wednesday October 23 2024
Thursday October 23 2025
Friday October 23 2026

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