Question

The modern periodic table has been evolved through the early attempts of
Dobereiner’s, Newland and Mendeleev. List one advantage and one limitation of all
the three attempts.

Answer 1

Dobereiner's -- advantage-- first person to classify elements on basis of atomic mass

limitation-- the triads given by him was applicable to only lighter element

Newlands -advantage -- introduced law of octaves which state that property of eight element is similar to first element

limitation--when noble gases were discovered the property of eight element was not similar to first element

Medeleev

advantage -- he arranged the elements on basis of atomic mass

limitation -- he arranged some elements with higher atomic mass before an element with low atomic mass