Question

position of isptopes in thr mendellev's and the modern periodic table.
plzz answer fast urgent

Answer 1

First of all, during the time of Mendeleev, scientists had zero knowledge about the isotopes. So when isotopes were discovered, they could not be placed in the periodic table. This was one of major drawback of his table.

When Moseley discovered the modern periodic table, he took the average mass of all isotopes according to their relative abundance and used them as atomic weight of elements. This was one of the advantages of this table.

So the major difference is that isotopes were not considered in Mendeleev's table whereas they were considered in modern periodic table


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