23 October 08

Three great celebrations in chemistry for 23 October:

1. Today marks the birthday (in 1875) of Gilbert N. Lewis, who originated the idea of the covalent (shared) chemical bond. He also created a simple method to symbolize the bonding in molecules, called Lewis electron dot structures.
2. Many chemistry teachers recognize 23 October as "Mole Day," creating a humorous holiday to honor the extraordinarily useful constant known as Avogadro's Number, which is about 6.022 X 10²³ (a VERY LARGE number). The mole is the fundamental measurement for all components in a chemical reaction. Avogadro's Number counts the number of atoms in exactly 12 grams (one mole) of carbon-12, which is also the number of water molecules in 18 grams (one mole) of water (about 3-1/2 teaspoons). So why celebrate "Mole Day" today? The date is 10/23, like the "power of ten" in Avogadro's Number. The most ardent celebrants awake in time to honor 6:o2 a.m., but our family observes it on Central Time or Mountain Time rather than Eastern Time.
3. This is National Chemistry Week, designated as the week in October that includes the 23rd.