Dmitri Mendeleev's development of the Periodic Table was based on his recognition of patterns among the known elements, which led him to predict the existence of undiscovered elements. His assertion regarding gallium's properties, despite initial skepticism from its discoverer, Paul Emile François Lecoq de Boisbaudran, ultimately proved accurate when Lecoq de Boisbaudran revised his measurements to align with Mendeleev's predictions. This incident highlights Mendeleev's confidence in his theoretical framework over empirical data, a stance that, while controversial, was validated by subsequent discoveries. Science philosopher Eric Scerri noted that Mendeleev's insights into elemental properties surpassed those of the chemist who discovered gallium.
PREREQUISITESChemistry students, historians of science, educators, and anyone interested in the evolution of the Periodic Table and the methodologies of scientific discovery.
http://www.slate.com/id/2258112/entry/2257317/Mendeleev picked apart Lecoq de Boisbaudran's data on the new element (soon named gallium). Mendeleev claimed, largely without evidence, that the accomplished Lecoq de Boisbaudran must have made mistakes when measuring gallium's weight and density, since they differed from Mendeleev's predictions.
The chutzpah here is incredible, but Mendeleev tended to trust his own instincts and formulas over mere evidence. Crackpots often do. The difference between Mendeleev and most crackpots is that Mendeleev was right: Lecoq de Boisbaudran soon had to publish an embarrassing retraction about gallium's weight and density, changing them to values that vindicated Mendeleev. According to science philosopher and historian Eric Scerri, "The scientific world was astounded to note that Mendeleev, the theorist, had seen the properties of a new element more clearly than the chemist who had discovered it."
FantasyQueen said:How did Dimitri Mendeleev know that some of the elements were missing/not discovered? How did he know that the missing elements existed? Did he find some sort of pattern when he created the Periodic Table?