Logo of the Atomic Weights Commission Logo of the International Union of Pure and Applied Chemistry


    IsotopeAtomic mass (Da)Isotopic abundance (amount fraction)
    180W 179.946 71(1)0.0012(1)
    182W 181.948 206(5)0.2650(16)
    183W 182.950 224(5)0.1431(4)
    184W 183.950 933(5)0.3064(2)
    186W 185.954 365(8)0.2843(19)

    In 1969, after evaluating the uncertainties associated with the mass-spectrometric measurements, the Commission assigned a value of Ar(W) = 183.85(3). For a number of years after that, in the absence of calibrated mass-spectrometric measurements, the Commission was concerned about a discrepancy between the recommended atomic weight and the results of earlier chemical determinations that yielded values of around Ar(W) = 183.90. In 1991, the Commission changed the recommended value for the atomic weight of tungsten to Ar(W) = 183.84(1), based on high-precision measurements with negative thermal ionization mass spectrometry.

    SOURCE  Atomic weights of the elements: Review 2000 by John R de Laeter et al. Pure Appl. Chem. 2003 (75) 683-800
    © IUPAC 2003


    Ar(W) = 183.84(1) since 1991

    The name derives from the Swedish tungsten for "heavy stone". The symbol W derives from the German wolfram, which was found with tin and interfered with the smelting of tin. It was said to eat up tin like a wolf eats up sheep. The element was discovered by the Swedish pharmacist and chemist Carl-Wilhelm Scheele in 1781. Tungsten metal was first isolated by the Spanish chemists Fausto Elhuyar and his brother Juan José in 1783.