Council Committee on Nomenclature, Terminology and Symbols

The Committee on Nomenclature, Terminology and Symbols held its open meeting on Monday, August 20, 2012. We received a report on the discovery of two new elements: number 114 and 116.  The Committee found that the proposed names and symbols follow a long tradition of selecting element names from geographic place names. Thus, the names Flerovium (element 114; symbol Fl) and Livermorium (element 116; symbol Lv) honor the two laboratories that cooperated in the discoveries. They join other elements named for other laboratories such as: Berkelium (element 97), Dubnium (element 105), Darmstadtium (element 110).

In previous reports from this Committee, Council was informed regarding the redefinition of the kilogram and the mole. The Committee on Nomenclature, Terminology and Symbols began its work with two goals: 1) to understand what is being done; and 2) to understand what it means to the practice of chemistry.

At its meeting in October 2011, the General Conference on Weights and Measures endorsed the concept of re-defining all of the SI Base Units on physical constants deemed “invariants of nature.”  The proposed new definitions, however, were not adopted. Instead, the Conference encouraged further work on the values of the physical constants to reach a target uncertainty of 20 parts per billion. Presently, the Planck constant that will define the kilogram has an uncertainty of 44 parts per billion.

The re-definition of the mole will be based on the Avogadro constant causing the mass of Carbon-12 to be determined experimentally and no longer be defined as 12.0 exactly. Presently, the uncertainty in the Avogadro constant is also 44 parts per billion.

The next General Conference on Weights and Measures is scheduled for 2014 rather than after the normal four-year interval that would place it in 2015.  Provided the target uncertainties of the physical constants have been met, the new definitions should be adopted at that time.

The Committee has begun preparation of a series of descriptions of the new definitions of SI Base Units. These descriptions are designed to address the chemical education needs of different grade levels and will be available on the Committee’s web site.

Peter Rusch, Chair, Committee on Nomenclature, Terminology and Symbols