Annual Mole Day created by Badger Chemist

By Mason Braasch
Department Communications

Almost any student who has taken a chemistry course – whether it be in high school, college, or elsewhere – will have a story about how they celebrated Mole Day with their class. Few know, however, that the creation of the day has ties to the University of Wisconsin–Madison.

Every October 23 from 6:02 a.m. to 6:02 p.m. chemists and chemistry students from around the world unite in celebration of Mole Day, an unofficial holiday that teaches the concept of Avogadro’s Number. The National Mole Day Foundation explains that Avogadro’s Number (6.02 x 1023), “is a basic measuring unit in chemistry” where “for a given molecule, one mole is a mass (in grams) whose number is equal to the molar mass of the molecule.” While the concept is taught in every basic chemistry course, it is an essential aspect of the science, thus warranting its very own holiday!

As part of National Chemistry Week, the American Chemical Society and the National Mole Day Foundation, as well as high schools from around the globe, engage people with chemistry and foster an interest in the science. Complete with a different theme each year (past themes have included AniMole Kingdom, Molar Eclipse and Rock N’ Mole), resources for teachers and students, fun activities such as the Molympics, and even merchandise, Mole Day is an essential part of connecting communities with the field of chemistry — and it was created by a UW–Madison alumnus.

Maurice Lee Oehler received his M.S. in chemistry from UW–Madison in 1961, under the advisement of Prof. Howard E. Zimmerman. He then went on to teach chemistry at Prairie du Chien High School, where the idea for Mole Day was born. On May 15, 1991, Oehler established the National Mole Day Foundation, which helps to engage chemistry students worldwide, create enthusiasm surrounding chemistry, and answer inquiries from students, chemistry teachers, college professors, retired chemists and anyone interested in the field. Since its creation in 1991, the National Mole Day Foundation has amassed more than 3,000 “mole-due” paying members.

Oehler passed away in January of 2020, but his legacy lives on in the continued passion for chemistry that is exhibited every year on October 23.

Bassam Z. Shakhashiri, an emeritus professor at the UW–Madison Department of Chemistry, was the president of the American Chemical Society (ACS) in 2012. He reflected on his involvement with ACS and their annual Mole Day celebrations, recalling how the scientific demonstrations, costumes and experiments are fun and lighthearted ways to generate curiosity for important topics.

“What’s important when we teach chemistry is to have students learn the fundamentals, but also learn how to connect chemistry to society,” said Shakhashiri, “The more that we talk about chemistry in a responsible manner, the better. We celebrate Mole Day as a way to connect our science to the general public.”Bassam Shakhashiri enjoys Mole Day with students through the annual American Chemical Society celebration.

Shakhashiri also emphasized that although Mole Day is filled with lighthearted activities, the reason we celebrate is to remember the very important chemical concept of Avogadro’s Number.

“When I was teaching general chemistry, I would always say something about Mole Day. I would try to be humorous, but also affirm that it was so important to know what Avogadro’s Number was and why it was useful in chemistry,” Shakhashiri recalled, “It provides an opening for doing all kinds of things that relate to important concepts in chemistry.”

This year, The National Mole Day Foundation has established the theme as HaMOLEton, which pays homage to the historical Broadway hit, “Hamilton.” Combining chemistry and history, this October 23 was one to remember.

Thirty years ago, Maurice Lee Oehler created Mole Day to share his passion for chemistry with students and help them appreciate science as he did. Today, the unofficial holiday is celebrated around the world — an accomplishment that some may call unbelieva-mole.