Question

limitations of Mendeleev's classification

Answer 1

1) position of hydrogen= hydrogen resembles both with halogens as well as alkali metals. it forms the positive ions like metals and negative ions like halogens. so position of hydrogen was not justified.
2) position of isotopes= position of isotopes could not be explained there was no space for isotopes although they different atomic masses.
3) wrong water order of atomic masses of some elements as mentally has place the elements in increasing order of atomic masses but Cobalt is placed before nikal to measure chemical property of the group this anomaly was not explained by mendleev.
4) similar elements in different groups and some elements with similar properties have been placed in different groups were placed.
5) cause of periodicity is not explained it was not explained that why the elements of same group show resemblance in their properties.

Answer 2

Answer:

Explanation:

Limitations of mendeleev’s classification :

(i) He could not assign a correct position of hydrogen in his periodic table, as the properties of hydrogen resembles both with alkali metals as well as with halogens.

(ii) The isotopes of the same element will be given different position if atomic number is taken as basis, which will disturb the symmetry of the periodic table.

(iii) The atomic masses do not increases in a regular manner in going from one elements to the next.

So it was not possible to predict how many elements could be discovered between two elements.