Table of atomic weights

First international table of atomic weights (78 elements listed). 

Ans. The atomic weight of fluorine is 19.0 amu, as seen in the periodic table or a table of atomic weights. The molecular weight of fluorine, corresponding to F2, is twice that value, 38.0amu. 

In calculating the moment of inertia, Ie = fiR 2, one customarily evaluates ja from the masses of the neutral atoms, considering this mass to be concentrated at the nucleus.1 Of course, this is an approximation, but it is a very good one, since electrons are so light. The atomic masses ma and mb in (4.5) cannot usually be gotten from tables of atomic weights, since most elements are mixtures of different isotopes. Each isotopic species has its own vibration-rotation levels. Masses for some common isotopes are given in the Appendix. 

CHEMICAL ELEMENTS. A chemical element may be defined as a collection of atoms of otic type which cannot be decomposed into any simpler units by any chemical transformation, but which may spontaneously change into other units by radioactive processes A chemical element is a substance that is made up of but one kind of atom. Of the over 100 chemical elements known, only 90 tire found in nature. The remaining elements have been produced in nuclear reactors and particle accelerators. Theoretical physicists do not all agree, but some believe that fission-stable nuclei should exist at atomic numbers 109. 114. and 126. Claims thus lur have been made for the discovery, isolation, or creation of elements up to 110. The element with the highest atomic number officially named and entered into the formal table of atomic weight is darmstudlium (Dx) with an atomic number of 110. 

We will finesse here the long and important struggle of getting a truly self-consistent table of atomic weights. If you are interested in the complex history of this problem and the clear solution to it proposed by S. Cannizzaro in 1860, there are many accounts available in books on the history of chemistry. One example is J. R. Partington, A History of Chemistry, Vol. IV, Macmillan, London, 1964. Relative atomic weights now are based on 12C =12 (exactly). 

PI 1.10 Use the relationships in Table 11.4 and the molecular data in Tables A6.2 to A6.4 of Appendix 6 (along with a table of atomic weights) to calculate... 

The relative molar masses of the gaseous components and the associated uncertainty in the relative molar masses are calculated from tables of atomic weights. The relative molar mass and uncertainties are combined with the gas purity and weighing uncertainty using the Gravcalc software. 

Table of atomic weights 1454 Index 1455 Reference data 1511 Abbreviations 1513... 

Hence, the atomic weight of nickel is Ni = 58 68, which value is adopted by the International Committee in their Table of Atomic Weights for 1918,... 

Compare his list of atomic weights with those of Dalton two decades before him and with the International Table of Atomic Weights of today, and marvel at the skill and accuracy of this giant among experimenters. 

---