Dmitri Ivanovich Mendeleev (1834 – 1907), Russian scientist, is famous for formulating the Periodic Law and creating a version of the periodic table of elements. He used the Periodic Law not only to correct the then accepted properties of some known elements, such as the valency and atomic weight of uranium, but also to predict the properties of three elements that had yet to be discovered (germanium, gallium, and scandium).
Professor of the Imperial St. Petersburg University; Corresponding Member (in the “Physical” category) of the Imperial St. Petersburg Academy of Sciences. Among the most famous discoveries is the periodic law of chemical elements, one of the fundamental laws of the universe, integral to all natural science. Author of the classic work “Fundamentals of Chemistry”.
Periodic Table of Chemical Elements
The periodic table of chemical elements (Mendeleev’s table) is a classification of chemical elements that establishes the dependence of various properties of elements on the charge of their atomic nucleus.
Structure
The most common are three forms of the periodic table: “short” (short-period), “long” (long-period) and “extra-long”. In the “super-long” version, each period occupies exactly one line. In the “long” version, lanthanides and actinides are removed from the general table, making it more compact. In the “short” form of recording, in addition to this, the fourth and subsequent periods occupy 2 lines each; The symbols of the elements of the main and secondary subgroups are aligned relative to different edges of the cells. Hydrogen is sometimes placed in the 7th (“short” form) or 17th (“long” form) group of the table.
Photo: USSR textbook for 8th grade of the secondary school (1986).
