Mass Migration: Chemists Revise Atomic Weights of 10 Elements
An international governing body has adopted a new definition of atomic mass (aka atomic weight) changing from specific values to intervals of masses to resolve 15 years of debate on one of the most fundamental of scientific concepts. In a list that only singer-comedian Tom Lehrer could love, hydrogen, lithium, boron, carbon, nitrogen, oxygen, silicon, sulfur, chlorine and thallium now all have new mass definitions."Back in high school, you opened your chemistry book and saw a table of standard atomic weights. Your teacher probably told you these were constants of nature. It turns out that that is not true," says Tyler Coplen of the U.S. Geological Survey, co-author of the document that redefines the masses of the aforementioned elements. Swapping the ease of a single number for the apparently clumsier interval of numbers has been controversial among some chemists, but additional precision in measurements...