National Mole Day recognizes a special number in chemistry. We’ll eliminate any visions of a burrowing creature celebration immediately. Chemists and chemistry students mark the occasion each year on October 23rd. 

More specifically, the celebrations take place between 6:02 AM and 6:02 PM. In the U.S., the time and date are written 6:02 10/23. The time and date are derived from Avogadro’s number. Avagadro’s number is approximately 6.02×10^23. Hence, defining the number of particles (atoms or molecules) in one mole of substance, one of the seven base SI units.

  • A mole is a unit of measurement used in chemistry to express amounts of a chemical substance.
  • Avogadro’s number is a historical term closely related to the Avogadro constant.
  • The Avogadro constant is named after the early 19th-century Italian scientist Amedeo Avogadro.

HOW TO OBSERVE #NationalMoleDay

There are several ways to celebrate this scientific day. Do you know how to use the mole in an equation?

  • Learn more about molecular science and Avogadro’s number.
  • Explore the international system of measurement using moles.
  • Test your knowledge of chemistry. Celebrate with other chemists and chemistry students.
  • Conduct a mole experiment. While conducting it, see how many puns you can tell.
  • In your classroom, do a video with your students demonstrating what a mole is. 
  • Create a rap about the mole. Be sure to include a little history of Amedeo Avogadro.
  • While reading up on Italian scientist Amedeo Avogadro, explore other chemists of his era.

Share your knowledge using #NationalMoleDay to post on social media.


An article in The Science Teacher in the early 1980s sparked National Mole Day. A chemistry teacher at Prairie du Chien Senior High School became inspired by the article and founded the National Mole Day Foundation on May 15, 1991. 

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October 23rd History


The first National Women’s Rights Convention began in Worcester, MA, taking the movement for women’s rights beyond individual regional efforts. During the convention, participants developed a set of conventions titled the Declaration of Sentiments. Some of the 68 women and 32 men who signed the declaration included Lucretia Mott, Elizabeth Cady Stanton, Marth Underhill, and Frederick Douglass, and Henry W. Seymour.


With songs like “Baby mine” and “When I See an Elephant Fly,” Disney released the animated musical Dumbo.


In an episode of the Belgian comic series named Johan and Peewit, the first Smurf appeared. The Medieval-themed comic created by Peyo introduced the little blue people in the episode “The Flute of Six Smurfs.”


The U.S. Supreme Court swears in Justice Clarence Thomas. He is the second black jurist to join the highest court in the country and replaced Thurgood Marshall.


Apple debuts the digital, portable media device, the iPod.


The biopic, Bohemian Rhapsody, is released. Starring Rami Malek as Freddie Mercury, the film earned four Academy Awards including Best Actor.

October 23rd Birthdays

John Heisman – 1869

The football player and coach is best known for bringing the forward pass to the game. In its early days, football meshed the skills and rules of rugby and soccer together. While soccer allows forward passes, rugby did not. Today, the Heisman Trophy is awarded to the most outstanding football player in the National Collegiate Athletic Association (NCAA) and was named after this football pioneer.

Ted Fujita – 1920

The meteorologist developed a scale identifying the intensity of a tornado. Today the Fujita Scale (also known as the F-Scale) is used by meteorologists around the world.

Johnny Carson – 1925

In 1962, Johnny Carson replaced Jack Paar as host of the Tonight Show. With humor, magic, and impersonations, the comedian entertained audiences for 30 years.

Pelé – 1940

Born Edson Arantes do Nascimento, the soccer player led his Brazilian team to three World Cup championships. Regarded as one of the world’s best professional soccer players, Pelé began playing professionally at the age of 16.

Gertrude Ederle – 1942

Before becoming the first woman to swim the English Channel in 1926, Ederle broke amateur swimming records and joined the U.S. women’s swim team winning gold at the 1924 Olympics in Paris.

Michael Crichton – 1942

The science fiction and thriller author has brought several titles to the big screen, including Jurassic Park, The Great Train Robber, and Twister.

Weird Al Yankovic – 1959

As a singer-songwriter, Yankovic produces satirical remakes of popular songs. Some of his more memorable songs include “Like a Surgeon,” “Word Crimes,” and “I Think I’m a Clone Now.”