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By: Joanna McNurlen

It’s October 23rd. To some of you, this means nothing. To others, this means a great deal. An exponentially great deal, even.

Lost? Here’s a hint: Amedeo Avogadro.

I can almost see some of your faces contorting in concentration. “Avogadro? As in guacamole?”

Not quite – though guacamole is tangentially related (more on that later). Amedeo Avogadro was an Italian scientist who came up with Avogadro’s number, which is the number of atoms or molecules found in a mole of a particular substance (6.022 x 1023). A “mole” is a unit of measurement: one mole of a substance has an amount of mass equivalent to the substance’s atomic mass. For example, since a water molecule’s atomic mass is 18, one mole of water has a mass of 18 grams. A mole of gold, which has an atomic mass of about 197, has a mass of about 197 grams.

Chemists can use Avogadro’s number to convert between macro and microscopic units of measure. For instance:

So by using this number, scientists can easily figure out that 10 grams of gold contain 3.06 x 1022 atoms of gold – all thanks to moles and Mr. Amedeo Avogadro.
In the early 1980s, a high school science teacher wrote to the cleverly titled The Science Teacher to suggest a holiday in honor of this unit of measurement and its associated constant. Some years later, in May of 1991, the National Mole Day Foundation was born.
The NMDF’s mission is to get people excited about chemistry by promoting “Mole Day”: an unofficial holiday dedicated to the celebration of Avogadro’s number, moles, and all things chemistry. When is this holiday? Why, today, of course.
Mole Day is celebrated from 6:02 AM to 6:02 PM on October 23rd (10/23) in honor of the famous 6.022 x 1023 constant. Each year, the National Mole Day Foundation provides a painfully punny theme for the festivities (this year’s is the groan-worthy “Molar Eclipse”), and high school chemistry classrooms around the country celebrate with science-themed songs, pun-filled jokes, and tasty treats for all to share.
Sure, it’s a little corny, but ultimately Mole Day is a fun way to get kids excited about chemistry, and it gives us science nerds a chance to inflict our love of puns upon the world. How will I be celebrating? By making GuacaMOLe, of course (told you it was related).


  1. seidensays posted this