gram is the unit of mass that is 1/1000 of a kilogram.
gram is the unit of mass that is 1/1000 of a kilogram.
what unit of mass is 1/1000 of a kilogram?
gram
all silicon-based approaches would fix the avogadro constant but vary in the details of the definition of the kilogram. one approach would use silicon with all three of its natural isotopes present. about 7.78% of silicon comprises the two heavier isotopes: si and si. as described in " below, this method would "define" the magnitude of the kilogram in terms of a certain number of c atoms by fixing the avogadro constant; the silicon sphere would be the "practical realisation". this approach could accurately delineate the magnitude of the kilogram because the masses of the three silicon nuclides relative to c are known with great precision (relative uncertainties of 1ppb or better). an alternative method for creating a silicon sphere-based kilogram proposes to use isotopic separation techniques to enrich the silicon until it is nearly pure si, which has a relative atomic mass of . with this approach, the avogadro constant would not only be fixed, but so too would the atomic mass of si. as such, the definition of the kilogram would be decoupled from c and the kilogram would instead be defined as atoms of si (≈ fixed moles of si atoms). physicists could elect to define the kilogram in terms of si even when kilogram prototypes are made of natural silicon (all three isotopes present). even with a kilogram definition based on theoretically pure si, a silicon-sphere prototype made of only nearly pure si would necessarily deviate slightly from the defined number of moles of silicon to compensate for various chemical and isotopic impurities as well as the effect of surface oxides.
alternative approaches to redefining the kilogram
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