The prospect of the dalton in the new SI: An educator's point of view

Abstract

If the definitions of the kilogram and the mole, based on exact values of the Planck and Avogadro constants, respectively, are accepted within the framework of the new SI, then the current definition of the dalton cannot be retained. Acceptance implies redefinition of the dalton exactly in terms of the kilogram. The redefined, exact dalton is useless in mass spectrometry, and hence, a new quantity for the carbon-12 reference mass would have to be established-against the principle of Ockham's razor. In order to remove the roots of this awkward concept, the kilogram based on the Planck constant, and the mole, consisting of a particular number of entities equal to the inexactly determined numerical value of gram-to-dalton mass ratio, should be included in the new SI system. Some controversies related to the concept of mole have been also briefly outlined. © 2013 The Author(s).