23 October 17

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. In the photo I am holding one mole of each substance: 56 grams of iron (nails), 342 grams of sucrose (crystals), 27 grams of aluminum (foil), and 18 grams of water (colored blue). Not shown directly in the photo is one mole of air (measured at 29 grams/mole), occupying 22.4 liters = about 6 gallons, at normal temperatures and pressures.