Beryllium placement

FIGURE 36 Photograph of beryllium tube plug-flow reactor (Bare et al., 2007) and oven with one-half of the oven removed to show placement of the tube. Reprinted from (Bare et al, 2007), Copyright 2007, with permission from Elsevier. 

The placement of the metal beryllium provided one of the most severe tests for Mendeleev s system. Its case proved to be historically significant because it involved a controversy that lasted a considerable period of time, ending with the complete vindication of Mendeleev s position. The question was whether the element should be assigned a valence of 2 or 3, which would affect its atomic weight and thus would in turn govern the position it took in the periodic table. 

But the placement of difficult elements such as beryllium, the accommodation of the newly discovered noble gases, and the ongoing struggle to position the rare earths all contributed to an atmosphere of productive debate that surrounded the periodic system. These factors may well have contributed just as much as the... 

Generally, it can be said that the Berichte provided information regarding successful predictions, problems with the reference of the atomic weight, placement of beryllium and the noble gases, and attempts to position the rare earths. These papers were written by known and lesser-known scientists. 

---