When was the periodic system of Mendeleev?
The periodic table is a periodic system of chemical elements, their classification. This system is a graphical display of periodic law. Many are interested in the question of when the periodic system of Mendeleev was discovered, in what year?
Attempts to open a table similar to the periodic table
As early as the 19th century, 63 chemical elements were discovered, and scientists have repeatedly attempted to establish patterns in this set. John Alexander Newlands tried to offer his version of the periodic system in 1866, however, it was compromised by the author. There were other attempts in the same decade to systematize the chemical elements, the closest he got to the final version was Julius Lothar Meyer.
Opening the periodic table
The first diagram of the periodic table was published by Dmitri Ivanovich Mendeleev in March 1869 in the journal RusskyChemical Society, the article was called "The ratio of properties with the atomic weight of the elements." There is a legend that says that the system of chemical elements Mendeleev saw in a dream. Once, when he was asked how the opening of the periodic system of Mendeleev was accomplished, he said: "I have been thinking about it for maybe twenty years, and you think: I was sitting and suddenly ... ready." Compiling the table, Mendeleev wrote on individual cards all the basic properties for each element, at that time 63 pieces were known. Then these cards were rearranged to them more than once, so that the series of elements with similar properties turned out, the series were also compared with each other.
The results of this painstaking work and became the first version of the scheme in 1869, the elements were placed horizontally in 9 rows and diagonally in 6 columns. Later, in 1870, D.I. Mendeleev published his second version of the system in Fundamentals of Chemistry, this is a more familiar and familiar form: horizontal columns acquired the appearance of eight groups arranged vertically, but the vertically arranged 6 columns from the first version were periods ranging from alkali metals to halogen.At the same time, periods began to be divided into 2 rows, while the elements that were part of a group of rows formed subgroups.
Differences of the periodic table from others
Mendeleev's work differed from others in that it classified the elements according to chemical similarity and atomic mass. Also in his table, he left unfilled cells for elements that were not yet open at that time. On the basis of all his works, Mendeleev formulated the Periodic Law in 1871.
Thus, the creation of the periodic system of Mendeleev falls on the year 1869, and finally it was finalized in 1870 and 1871. This system received worldwide recognition in 1880, as the main law of theoretical chemistry.