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. Some people arise at 6:02 a.m. on this day for special significance. On the Periodic Table, the atomic weights stand for the number of grams of each element that contain one mole of those atoms. The mole unit is fundamental in chemistry because it counts the number of items (atoms, ions, molecules, etc.) that exist in one formula weight of that substance. For example, I am holding 58 grams (roughly 2 ounces) of table salt, which contains one mole of sodium atoms and one mole of chlorine atoms. That's the same number of water molecules that exist in 18 grams of water (a little more than one tablespoon). Measuring moles is essential in understanding chemical reactions. Added note: This is also Mother-In-Law's Day, which I celebrated in several ways with Wilma Wollenweber!