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 ...

For the first time those little numbers that appear beneath some of the commonest elements in the periodic table boxes are about to change from a single value to an interval of numbers An ...

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 ...

One hundred years ago the Harvard University chemist Theodore William Richards was awarded the 1914 Nobel Prize in Chemistry for his accurate determination of the atomic weights of many elements. This ...

Precise values for the masses of the nuclei of the simplest atoms, such as hydrogen and helium, are crucial for experiments targeting big unsolved problems in physics. A technique known as ...