Dmitri Mendeleev applied systems thinking to understand the properties of the then-known atomic elements to predict the nature of undiscovered elements.
February 2016 marks the 182nd birthday of Dmitri Mendeleev. He was a systems thinker and is considered to be the father of the modern periodic table. He applied systems thinking to understand the periodic trends of the then known chemical elements.
Systems thinking seeks to discover patterns of behaviour caused by the underlying system architecture. By understanding system architecture, systems thinkers can make predictions about future behaviour. Mendeleev’s work is classic systems thinking.
Before Mendeleev there had been a number of attempts to tabulate the elements, most notably by the Julius Lothar Meyer. Meyer recognised that periodicity was associated with valency, or the combining power of elements. Meyer published his first periodic table in his book The Modern Theory of Chemistry in 1864. In it he ordered twenty eight elements into six vertical groups. When he republished his book in 1870 he had his table to fifty four elements in nine groups. However, his table ignored a number of the then-known elements, including hydrogen, yttrium, thallium and uranium.
Mendeleev worked completely independently of Lothar Meyer and created his first periodic table in 1869. This table included sixty three elements arranged in six vertical groups. By 1871 he had rearranged his table with eight groups in the more familiar horizontal arrangement that forms the basis of the modern periodic table.
Why is Mendeleev rather than Meyer remembered as the father modern periodic table? What made Mendeleev’s table special when compared to Meyer’s? The answer lies in systems thinking.
Mendeleev correctly surmised that the atomic weights of some elements were incorrect. For example he placed iodine after tellurium although its known atomic weight was smaller to align it with bromine and chlorine, which have similar properties. Mendeleev’s original table predicted the atomic mass of four hitherto unknown elements, scandium, gallium, technetium and germanium. Scandium, gallium and germanium were all discovered within seventeen years of the publication of Mendeleev’s first table. Technetium was finally discovered in 1936. His next table produced in 1871 had spaces for a further twenty seven unidentified elements.
The beauty of Mendeleev’s table was that it described an architectural model that not only provided insight into the nature of elements but also provided foresight that led to the discovery of new chemical elements, which continues to this day. It also inspired the work of physicists to understand the structure of atoms.