In the year 1913, Maujle proved that the basic property of an atom is the atomic number and not the atomic number as the basis of periodic classification of atomic mass.
1-location of hydrogen-
The effect of the hydrogen atom cooperates by taking an electron like the elements of the group and by accepting an electron like the elements of the seventh group, so it is justified to place it in the first and seventh group.
2-location of rare earth element-
All the soil elements have been kept in one place. Because they have the same number of electrons in their outermost orbitals.
3-location of isotopes-
All isotopes of the same element have the same atomic number, so they should be kept at the same place.
4-Putting the heavy elements before the light elements-
On the basis of atomic mass which come before the elements of the heavier ones. Their place is proper on the basis of atomic number like argon has atomic weight 39.84 and atomic number 18, which is justified to put potassium before atomic number 39.1 and atomic number 19.
5-Putting dissimilar elements in the same group-
In Mendeleev’s periodic table, ia is placed in the same group, while there is a difference in their fold, in the modern periodic table IA and IB are considered separately and they are kept away from each other.
Read in Hindi: Mendeleev’s periodic table-