The Columbia Encyclopedia, Sixth Edition. 2001-07.
mole, in chemistry
in chemistry, a quantity of particles of any type equal to Avogadros number, or 6.02×1023 particles. One gram-molecular weight of any molecular substance contains exactly one mole of molecules. The term mole is often used in place of gram-molecular weight; e.g., one speaks of 18 grams of water as one mole of water rather than as one gram-molecular weight of water. The mole is a unit in the International System of Units (SI).