Level: Introductory, Intermediate
The values of the constants provided here are recommended for international use by CODATA and are the latest available. Termed the " 2018 CODATA recommended values," they are generally recognized worldwide for use in all fields of science and technology. The values became available on 20 May 2019 and replaced the 2014 CODATA set. They are based on all of the data available through 31 December 2018. The 2018 adjustment was carried out under the auspices of the CODATA Task Group on Fundamental Constants.
Also available is an Introduction to the constants for nonexperts.
New Definition of the Mole
After an extensive consultation with the chemistry community, and following a review and critical evaluation of the literature, IUPAC is recommending a new definition of the mole based on a specified number of elementary entities:
The mole, symbol mol, is the SI unit of amount of substance. One mole contains exactly 6.022 140 76 × 1023 elementary entities. This number is the fixed numerical value of the Avogadro constant, NA, when expressed in mol−1, and is called the Avogadro number.
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Conversion Factors are given for mass, energy, energy dose, ion dose, time and activity.
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Radiological Limits give radiation limits for workers, apprentices and students, and members of the public. The values given are recommended by international organisations such as Euratom, ICRP, and IAEA and the national German authorities. Dose limits given are for whole and partial body (eyes, hands, skin, etc.) exposure. For apprentices and students, data is given for ages less than 16 years, 16 -18 years and over 18 years old.