For those who celebrate the Lunar New Year, 2019 is the year of the pig. But for chemists around the world, 2019 marks the 150th anniversary of the first publication of the periodic table by Mendeleev. Therefore in December 2017 during the United Nations' 74th Plenary Meeting, it was declared that 2019 is the International Year of the Periodic Table of Chemical Elements.
The periodic table is considered as a uniting symbol for all disciplines within natural science. Naming 2019 after the one of the greatest achievement in the history of science (and humankind), UN hopes to promote the role of chemistry plays in everyday life and its potential to resolve some of the global challenges we are facing in agriculture, climate, environment, energy, and health.
Russian chemist Dimitri Mendeleev is credited as the father of the periodic table, but he was not the only scientist who saw the periodic pattern of properties of various elements and attempted line them up in a sensible, logical manner. However, Mendeleev did strike an ingenious difference while shaping his version of the table.
He arranged the elements in the order of increasing relative atomic mass, which was carefully calculated. To keep the group of elements consistent, for instance sharing similar chemophysical characteristics, he witched the order of a few elements in his original design. Also, Mendeleev reserved some empty spots in his table because he predicted that the yet-to-be-discovered elements will one occupy them.
Since the publication of Mendeleev’s periodic table, there have been fifty-five new elements added, all of which fitting right into the existing classification according to their atomic mass. The last four empty spots got occupied in the early 2000s, due to the confirmed discovery of elements 113, 115, 117 and 118. The four elements, most of which have less than a second half-life, are all artificially produced through particle bombardment. Mid-2016, the International Union of Pure and Applied Chemistry (IUPAC) has officially named them nihonium, moscovium, tennessine, and oganesson.
With no more "spots" to fill, the periodic table might seem "completed". For some, even though there might be new elements to be added to the table's wide open, unoccupied eighth row, finding them is not just a cost-ineffective exercise, but also represents little value to science. Experience told us that elements on the heavy end of the spectrum are inherently unstable and do not last long enough to permit any meaningful applications.
But others beg to differ. In Dubna, Russia, $60 million dollars have been invested in building a new discovery facility known as the Superheavy Element Factory (SHEF), where scientists expect to create new elements that fill the eighth row of the periodic table. These exotic, new elements are theorized to have otherworldly traits, or even defy the table's very periodicity (they might exhibit distinct properties are different from other members in the same group/column).
In the end, it seems that 150 years-worth progress in science has not given us a definite answer to the very question that Mendeleev once asked: how far the table can go? The sesquicentennial of the periodic table, as most hope, will keep inspiring humanity to discover, innovate, and push the field of chemistry forward.
Where does the periodic table end? (Science Magazine)
Source: the conversation