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Periodic table of elements game quiz6/21/2023 ![]() The classic example is of iodine (atomic mass 126.9) and tellurium (127.6). If the situation demanded it, he boldly interchanged the positions of elements. In a stroke of genius, Mendeleev prioritised an element’s properties over its atomic mass. The genius of MendeleevIn 1869, the Russian chemist Dmitri Mendeleev, along with the German chemist Lothar Meyer, proposed a tabulation of the elements which was different from previous arrangements in at least two ways. The real periodic table, however, was yet to come. ![]() In 1864, the British chemist John Newlands made the same observations. Such columns made for a more orderly arrangement than a single row, which would have gone on forever. The two elements could thus be placed in the same vertical column so could potassium further down the list. In other words, the properties of one element would repeat themselves in another element after a certain “period” as one proceeded in order of atomic mass.įor example, lithium and sodium, separated by 16 places in the order of atomic masses, were chemically similar in many respects both metals are highly reactive, and both release hydrogen gas when they react with water. De Chancourtois arranged the elements in order of their atomic masses, and noticed a “periodicity” in their chemical properties. At that time, scientists already knew the mass of an atom of each known element although the technology did not exist to isolate and weigh the atoms, these atomic masses could be calculated by observing what amounts of one element combined with what amounts of another element to create a certain amount of a compound. In 1862, a French geologist, Alexandre-Émile Béguyer de Chancourtois, found a pattern. But no such order was immediately apparent, with each element coming with its own set of properties. The number of known elements was growing, and scientists wanted to order them in a meaningful way. ![]() ![]() Why a table was madeTo get a sense of its significance, it is necessary to first recognise the circumstances under which the periodic table was created in 1869. It is marked by the tireless efforts of scientists in difficult conditions, their failures and insightful predictions, and refinements made to the table as scientific knowledge expanded. The backstory to the construction is no less fascinating. Atomic structure, in fact, explains why the periodic table works, but this was understood much after the table was first constructed. The periodic table orders all the elements in neat rows and columns as a guide to their properties and atomic structures. ![]()
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