Question

Achievements of Mendeléev's Periodic Table.
(Unnnecesary answers will be reported)

Answer 1

Answer:

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Answer 2

Answer:

The concept of the modern periodic table is derived from the Mendeleev's periodic table.

Explanation:

Mendeleev was the first scientist to be successful in the categorization of the elements on the basis of their nature. He had arranged the elements in 8 columns and 7 rows. He denoted the columns as the group and the rows as the period. Though when he synthesized the elements then out of 118 elements only 63 elements were discovered and that's why he had categorized only those 63 elements but he left some gaps for the undiscovered elements and also had given the conception about the unknown elements correctly.

It is similar to the modern periodic table, done by Henry Mosley because, both in modern and Mendeleev periodic table, the metallic property of the elements increases with the increase in number of the period and decreases with the increase in the number of the groups.

It is different from modern periodic table because, in modern periodic table the elements are categorized on the basis of the atomic number but, in Mendeleev's  periodic table the elements are categorized on the basis of their mass number.