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 ...

Isotopes close isotopesAtoms of an element with the same number of protons and electrons but different numbers of neutrons. are atoms with the same atomic number but different mass number. These two ...

Over the past few decades, the atomic mass of the electron has been determined using several Penning-trap experiments, because exploration of the scope of validity of the Standard Model requires an ...