Ans : Mendeleeve’s Law of Classification :
Mendeleeve in 1869 arrange elements in order of increasing atomic masses. He placed chemically similar elements vertically beneath each other & concluded that :
“The physical & chemical properties of elements are a periodic function of their atomic weights.”
Advantages Of Mendeleeve’s Periodic Table (Salient features):
Systematic Study Of Elements :
It helped in the systematic study of elements.
Concept Of Periodicity :
It forcefully proved the concept of periodicity. Prediction Of New Elements : Prediction of new elements is made possible.
Correction Of Atomic Masses :
Mendeleeve’s periodic table helped in correcting many doubtful atomic masses.
Disadvantages Of Mendeleeve’s Periodic Table (Drawbacks):
Wrong Placement Of Some Elements :
He placed certain elements of higher atomic masses before elements of lower atomic masses.
No Space For Isotopes :
It does not provide space for isotopes of elements.
Dissimilar Grouping of Some Elements :
Some elements were wrongly placed in dissimilar groups like alkali metals placed with coinage metals.
No Idea Of Atomic Structure :
It failed to give the idea of atomic structure.