Sunday, January 16, 2011

Historic Change: Just in time for the International Year of Chemistry

The year 2011 has been designated as the International Year of Chemistry. The IYC is an official United Nations International Year, proclaimed at the UN as a result of the initiative of IUPAC and UNESCO.

For the first time in history, a change will be made to the atomic weights of some elements listed on the Periodic table of the chemical elements posted on walls of chemistry classrooms and on the inside covers of chemistry textbooks worldwide. IUPAC will feature the change in the standard atomic weights table as part of associated IYC activities. The new table, outlined in a report released this month, will express atomic weights of 10 elements -- hydrogen, lithium, boron, carbon, nitrogen, oxygen, silicon, sulfur, chlorine and thallium -- in a new manner that will reflect more accurately how these elements are found in nature.

Analytic techniques have improved so that we can more precisely measure atomic weight and scientists have found that some are not static, but will be expressed in intervals. For example, sulfur is commonly known to have a standard atomic weight of 32.065. However, its actual atomic weight can be anywhere between 32.059 and 32.076, depending on where the element is found. Read more on the Science Daily website.