There have been some changes in the Periodic Table of Chemical Elements. The International Union of Pure and Applied Chemistry (IUPAC) has decided to revise the atomic masses of 19 elements in the periodic table. The International Union of Theoretical and Applied Chemistry voted to change the standard atomic mass of 19 elements: aluminum, beryllium, holmium, gold, yttrium, cadmium, magnesium, molybdenum, niobium, praseodymium, selenium, scandium, thorium, thulium, phosphorus, fluorine and cesium. Most of…
There have been some changes in the Periodic Table of Chemical Elements. The International Union of Pure and Applied Chemistry (IUPAC) has decided to revise the atomic masses of 19 elements in the periodic table.
The International Union of Pure and Applied Chemistry voted to change the standard atomic mass of 19 elements: aluminum, beryllium, holmium, gold, yttrium, cadmium, magnesium, molybdenum, niobium, praseodymium, selenium, scandium, thorium, thulium, phosphorus, fluorine and cesium.
Most of the amendments affected only the last decimal places. For example, the atomic mass of gold has changed from 196, 966569 (4) amu. at 196, 966569 (5) amu, where the figure in parentheses indicates the uncertainty in the following figures. True, there are a couple of exceptions: the mass of molybdenum instead of 95.96 (2) will be 95.95 (1), and the mass of selenium will increase from 78.96 (3) to 78.971 (8). And the most significant change, as noted by the secretary of the IUPAC Commission on Isotopic Composition and Atomic Weight, Juris Meija, will undergo the mass of non-metallic selenium, since information about it has not been revised since 1934 - this is a rare case. Usually, data on the atomic mass of elements are revised much more often.
In general, seemingly minor changes, but in reality they will play a large practical role in the field of chemistry and nuclear physics.
- Accurate knowledge of atomic masses is essential for understanding the fundamental laws of physics. I remember how in 2005 scientists decided to double-check the validity of the Einstein formula E = mc2, and this was done only thanks to accurate knowledge of the atomic masses of silicon and sulfur, says Meija.
Note that all the rules, standards and definitions in the field of chemistry are approved by the International Union of Pure and Applied Chemistry.
Marina Morskaya
Next: HP Unveils Convertible Laptop