Less heavy metal

The International Union of Pure & Applied Chemistry, better known as IUPAC, has redefined the atomic mass of ytterbium to 173.045, down from 173.054, a 0.0052 percent drop. IUPAC's Commission on Isotopic Abundances & Atomic Weights re-evaluates atomic weights every two years and based on work by mass spectrometrists at China’s National Institute of Metrology published in the Journal of Analytical Atomic Spectrometry has given Yb its new vital statistic. Additionally, in the process of carrying out the MS studies, the team has thus created an ytterbium isotopic certified reference material in nitric acid solution which they propose as the delta zero reference for the weight-loss metal.