The International Union of Pure & Applied Chemistry, IUPAC, has redefined one of the fundamental units of chemical currency - the mole. The well-known textbook definition of the mole is usually written as "A mole contains as many elementary entities as there are atoms in 12 grams of carbon-12". However, as efforts to modernise all SI units are currently underway, IUPAC and other interested parties suggested that it was time for a carbon omission. The new definition of the mole avoids any arbitrary quantities that would have to be measured and instead fixes the Avogadro Constant at precisely 6.02214076x10^23. Thus a mole is now simply defined as comprising of this number of elementary entities.
Moles redefined by carbon omission