Question

How did the position of 35 17cl and 37 17cl placed into modern periodic table

Answer 1

In Mendeleev's periodic table,the difference between atomic masses of two consecutive elements is not same 35 cl &37cl.Moseley found out the atomic number of the elements. The atomic number of any element is increased by one unit from the atomic number of subsequent element

Isotopes 35 17cl &37 17cl occupy the same position in the modern periodic table. Both isotopes have the same atomic number.

In the modern periodic table, the elements are arranged in the order of their increasing atomic numbers,that the problem of discepancy in the pairs of isotopes elements observed in the Mendeleev's periodic table was solved.