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=== Mole ===

The '''mole''' (symbol mol) is the unit of [[amount of substance]]. Its definition depends on that of the kilogram. It is that mass of any substance having as many ''elementary entities'' of that substance as are to be counted in 12 grams of [[carbon]]-12. An ''elementary entity'' is either an [[atom]] or a [[molecule]]--but for an [[ionic compound]], the number of elementary entities is the total number of [[cation|cations]] and [[anion|anions]] required to make the compound electrically neutral.