Thank you for bringing to my attention the recent International Union of Pure & Applied Chemistry report “Atomic weights of the elements 2009” (C&EN, Dec. 20 ...

Ytterbium is a bit lighter than previously thought: Its standard atomic weight is now 173.045, down from 173.054, as approved by the International Union of Pure & Applied Chemistry (IUPAC) in August.

How does one go about measuring the mass of an object? Mass is defined as the amount of matter an object contains. This is very different from weight, of course, as the mass of our object would remain ...

For four years, James Chadwick was a prisoner of war in Germany. When World War I ended, he returned to his native England to rejoin the mentor of his undergraduate days, Ernest Rutherford. Now head ...

As the International Committee on Atomic Weights has not provided a table since 1921, the British Sub-Committee published in the Journal of the Chemical Society of January last a revised table of ...

IN a paper on the absorption of Röntgen rays (Journal de Physique, p. 653, 1901) M. Benoist shows the connection between the transparency to X-rays of elementary substances and the atomic weight of ...