Question

limitations of mandeleev,s periodic table in points​

Answer 1

Explanation:

position of hydrogen is in certain

position of isotopes is not possible

aromalous pair

Answer 2

$\huge \mathbb \fcolorbox{black}{pink}{ANSWER}$

Limitations Of Mendeleev's Periodic Table

✦ Anomalous position of Hydrogen

Hydrogen as 1 electron in their outermost shell and alkali metals also have 1 electron in the outermost shell .

Therefore many properties of hydrogen are same to those alkali metals.

Hence , hydrogen can be placed along the group of alkali metal in the Mendeleev's Periodic Table.

✦ Position of isotopes

{ isotopes : those element whose atomic number is same but atomic mass is different . }

The Mendeleev's Periodic table was based on the increasing order of atomic masses and isotopes of the elements have different atomic masses , therefore they should be placed at different position , but due to the same chemical properties they are placed in the same position.

Thus , isotopes of the element posed a challenge to Mendeleev's Periodic Table.

✦ Different groups of elements within sub groups

In the Mendeleev's Periodic Table , elements placed in a group having similar chemical properties . But there is no similarity in the properties of elements in two sub groups.

For example , Li , Na , K , Rb , Cs present in group I A are quit different from Cu , Ag , Au in group II B .

✦Uncertainity in prediction of new elements

In the Mendeleev's Periodic Table , elements are arranged in increasing atomic masses . But the atomic masses do not increase in regular manner in going from one element to the next .

Further , the difference in atomic masses between two successive elements is small among lighter elements and large in heavier elements .

Therefore , it is not possible to predict how many new elements could be discovered between two known elements especially among heavier elements.

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❁ Extra Shots❁

☞ Mendeleev is also called as father of Modern Periodic Table .

☞ He was the first person to arranged all the 63 elements that were discovered that time into groups { vertical columns } and periods { horizontal rows } .

☞ The noble gases like Ar { Argon } , Ne { Neon } were not known when Mendeleev give his periodic table . These gases were discovered much later by one of the student of Mendeleev , Henry Moseley.

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