Question

What are the merits and demerits of Dmitri Mendeleev's periodic table?

Answer 1

Answer:

Demerits of Mendeleev Periodic Table. He was unable to locate hydrogen in the periodic table. Increase in atomic mass was not regular while moving from one element to another. Hence, the number of elements yet to be discovered was not predictable.

Explanation:

Merits of Mendeleev Periodic Table

Answer 2

$\huge{\mathfrak{\red{\underline{\underline{Solution:-}}}}}$

${\bf{\underline{\underline{Merits\;of\;Mendeleev's\;periodic\;table:-}}}}$

❈ Arranged 63 elements in a systematic order according to their increasing atomic masses and formula of their oxides and hydrides.

❈ He left gaps for the undiscovered elements.

❈ He correctly predict the properties of undiscovered elements. Eg. scandium, germanium, gallium, etc.

❈ Noble gases got a separate group without disturbing the table.

❈ As the elements were classified into groups, it proved very useful in studying and remembering the properties of a large no. of element in systematic way.

${\bf{\underline{\underline{Demerits\;of\;Mendeleev's\;periodic\;table:-}}}}$

❈ Position of hydrogen was not justified.

❈ There was no space left for isotopes in his table.

❈ Some elements having higher atomic mass were placed before those having lower atomic masses. For example - Co with higher atomic mass was placed before Ni having lower atomic mass).

❈ Two similar elements like Cu and Hg were grouped differently.

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