Seeking Order The Periodic Table

Chemistry at the beginning of the nineteenth century was in a position analogous to Ptolemaic astronomy. Around 100 C.E., Ptolemy created his astronomical system, which could be used to accurately chart the movement of all the visible planets, the sun, and the moon. His system worked perfectly well for navigation, time keeping, and all the other activities for which knowing the place of celestial objects was needed. Yet, Ptolemy s system had a philosophical problem. Each of the planets had its own system of movement, and the laws of planetary motion were different from those that governed motion on the Earth. Newton s astronomy and physics put all the planets, the stars, and motion here on Earth into a single system. 

Part of the reason that there was increasing pressure to find a unifying system was that the number of elements had almost doubled from the time of Lavoisier. Lavoisier had listed 33 elements, but by 1844 an additional 31 new elements had been added to the list. There was a slowing of discovery between 1844 and 1859, but two new elements were added when Robert Wilhelm Bunsen (1811-1899) and Gustav Robert Kirchhoff (1824-1887) announced 

Kirchhoff worked out the laws of spectroscopy and in 1859 published his findings, which included three laws  

An incandescent body gives off light in a continuous spectrum. 

An excited (heated) body gives off a bright-line spectrum. 

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In order to seek for non-iron catalysts to replace iron catalysts, many researchers, as Mittasch did in the past, have studied metal nitrides extensively. They expected to get some valuable information on catal dic properties of metal elements in the periodic table by this indirect way. 

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