Avagrado
&
The Mole
As this site is dedicated to the Mole I must first explain what a Mole is, and it is not a furry little garden pest as I first thought.  No, a Mole is a uniform measurement for molecules (specifically, 6.02 * 10 to the 23 molecules).  It may not immediatly be clear why we must have this extra number in an already difficult enough area, but eventually it is obvious that this magnification of an element helps to make a number more easily worked with.

The specific definition of a mole is the ammount of matter that contains as much matter as 12 grams of carbon.  Experimentally speaking this is some where around 6.0221367 times 10 to the 23.

Amedeo Avogrado (1776 - 1856) was the Italian scientist whom first declared his hypothesis that came to be known as the Mole or Avogrado's Number.