Question

How did chlorine 35 and chlorine 37 from Mendeleev table get fixed in mordern periodic table

Answer 1

this is because the modern periodic table is based in atomic no. of element

in detail,
In Mendeleev's periodic table the properties of elements are the periodic function of their atomic masses.
that's why they unable to ensure the correct position of isotopes like cl 35 and cl 37 as the masses are different for the same element ,
but later ,Henry Moseley showed that anomalies in arrangement of elements could be removed when the elements were arranged in order of increasing atomic number
that's why the isotopes of chlorine took correct position in modern periodic table .

I hope this may help you

Answer 2

heya friend!!☺☺
here's your answer!!☺

Mendeleev's periodic table was made on the basis of increasing atomic mass number of the elements.
hence, as both isotopes of chlorine have different atomic masses they were given different positions.

But, the morden periodic table is based on the basis of increasing atomic numbers...as a result they two isotopes of chlorine were gone same position in the periodic table.

hope it helps you!!☺☺