We can clearly see the periodic table everywhere. It is one of the most important and successful chemical discoveries to date. To create the complete and latest periodic table, many scientists and chemists were involved. One of the most involved chemists is Dmitri Mendeleev, originally from Russia. He contributed greatly to finding the elements and was the first to use the periodic law in his periodic table. Say no to plagiarism. Get a tailor-made essay on “Why Violent Video Games Should Not Be Banned”? Get an original essay What did Mendeleev include in the periodic table? Are there any errors in Mendeleev's periodic table? Although Mendeleev's periodic table provided a lot of support for developing the later table, several reasons show that there were still errors in his table that was found. By the time Mendeleev became a teacher in 1867, he wrote a textbook called Principles of Chemistry (1868-1870). The first reason he wrote this book was to prepare for his lesson. It was then that he made his most important and popular discovery. When he tried to classify elements based on their chemical properties, he observed patterns that led him to postulate his periodic table; he claimed to have anticipated the complete association of the elements in a dream. He said: “I saw in a dream a table where all the elements fell into place as required. When I woke up, I immediately wrote it down on a piece of paper, only in one place a correction seemed necessary to me later." Mendeleev's dream of the periodic table of elements in its completed form is apparently specious, despite its repeated quotes Not only is there no dream report, but the evidence relies on a colleague's second-hand account. Kedrov's examination of archival materials indicates that Mendeleev had already discovered the periodic table. the alleged dream took place; and a completely plausible dream occurred a little later, describing an improved representation of the periodic table. Mendeleev had developed the complete version of the periodic table and made a formal presentation to it. the Russian Chemical Society, entitled "The dependence between the properties of the atomic weights of the elements". There are several differences between Mendeleev's periodic table and the later periodic table. First, Mendeleev's periodic table based on atomic mass, but our table based on atomic number. Next is the number of elements. When our table has approximately 118 elements, Mendeleev's table contains approximately 66 elements. In Mendeleev's periodic table, transition elements are included with other elements. In the modern periodic table, the transition elements are placed in a separate block. According to Mendeleev, isotopes with different atomic weights should be placed in different positions, but no positions are assigned to them and no justified reasons have been explained. In the modern periodic table, isotopes are assigned the same position because they have the same atomic number. The main idea of ​​the system is that the factors are arranged in order of their atomic masses. Chemical properties recur periodically so that elements with the same properties divide into a single group according to the arrangement of the periodic law. The only error here is that iodine, which is certainly the chemical analogue of bromine and not selenium, had a smaller atomic mass than tellurium, whose resemblance to selenium was beyond doubt. Tellurium had already been discovered before iodine,.