23 October 26

Happy Mole Day! Chemists around the world celebrate Mole Day on October 23 (10-23) because those digits match the exponential part of Avogadro's Number, 6.02 X 10²³. A's Number is very special because it helps compare the amounts of substances that react. It's a much more meaningful measurement than weight or volume. My tie shows elements on the Periodic Table, where the atomic weights show how many grams of each element contain one mole of those atoms. The mole unit is fundamental in chemistry because it counts the number of items (atoms, ions or molecules) in one reacting unit of that substance. In the extra photo I am holding 58 grams (roughly 2 ounces) of table salt, which contains one mole of sodium atoms (23 grams) and one mole of chlorine atoms (35 grams). Another example is water, where 18 grams of H₂O (a little more than one tablespoon) contains one mole of water molecules.