Question

State two limitations of Mendeleev classification

Answer 1

1.
The position of hydrogen was not correctly defined. It was placed in group I although it resembles both the group I elements - the alkali metals and the group VII elements-the halogens, in their properties. 
2.

The position for lanthanides and actinides were not included in this table.

Answer 2

1 he could not give a specific postion to hydrogen because it behaved likeM alkalis as well as halogens.
2 he did not place isotopes of elements in the periodic table.