Tech UPTechnologyThe origin of the periodic table

The origin of the periodic table

The periodic table is a system of distribution and organization of chemical elements developed by Dimitri Ivanovich Mendeleev in 1869 . The creation of a system like this had been the subject of study throughout the nineteenth century and other scientists such as Antoine Lavoisier, Johan Dobereiner or John Newlands had already raised previous models that ended up being discarded for one reason or another. Mendeleev’s approach became a revolution for the world of chemistry .

The Russian scientist managed to distribute the known elements so that they followed an increasing order with respect to their atomic weight and at the same time were grouped according to similar characteristics or properties following a periodic pattern (hence the name). These similarities are produced between the different elements that are in the same column and that allowed to predict the properties of elements that had not yet been discovered and for which Mendeleev left blank gaps that were filled in over time.

His new periodic law was made known to the Russian Chemical Society in March 1869, stating that “the elements were grouped according to their atomic weight and had a clear periodicity in their properties.” This first design included the 70 chemical elements known at the time and gained popularity after the discovery of gallium, scandium and germanium, elements that had been predicted in the Russian chemist’s model . Despite its milestone, Mendeleev missed the chance to win the Nobel Prize in Chemistry in 1906 and died shortly thereafter.

In 1913 the English chemist Henry Moseley determined, through the use of X-rays, the nuclear charge of the elements and decided to rethink the 1869 design by ordering the elements according to their atomic number (the number of protons that each atom of that element has ) increasingly. The fact that the placement of many elements remained the same demonstrates Mendeleev’s good judgment in choosing the criteria for his table .

At present, the Moseley model is still used, which has 118 chemical elements distributed in 7 rows and 19 columns, in addition to the lanthanides and actinides . The elements are grouped into metals (on the left side of the table), nonmetals, and semi-metals. In each position of the table, in addition to the name and abbreviation of the element, its atomic number according to which they have been distributed, its valence electrons (electrons of the last layer that determine the properties and reactivity of the elements) and , in many cases, its atomic weight.

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