Question

$\huge \bold{ \underline{ \mathbb{ \red{QUESTION :-}}}}$
1) Discuss the limitations of Mendeleev Periodic table.
2) Mention some limitations of long form of periodic table.

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Answer 1

Answer:

1) a Though Mendeleev was almost successful in arranging the elements on the basic of their properties in his periodic table, the periodic table had some serious drawbacks such as -

▶ In some cases, in order to place the elements having similar properties in the same group, Mendeleev placed some elements with higher atomic weight before element having lower atomic weight.

▶ The position of hydrogen in Mendeleev's periodic table was controversial.

▶ In some cases, Mendeleev put elements having similar properties in different groups while elements having different properties in the same group.

▶ Though the atomic weights of different isotopes are different, they were not given different positions in the periodic table.

2) The long form of periodic table successful eliminated a number of drawbacks of Mendeleev's periodic table. However, the long form too has a few limitations. Which are discussed below -

▶ Even in long form of periodic table, the position of hydrogen is still controversial. Hydrogen cannot be placed in a definite group.

▶ Depending on the electronic configuration, it should have been placed in group -2. But it is placed in group -18 with other noble gases.

▶ Like Mendeleev's periodic table, the lanthanides and actinides are placed separately in two different rows below the main periodic table. The elements could not be placed in individual groups in the periodic table.

Answer 2

Answer:

1) Limitations of the Mendeleev periodic table are listed below. Elements with large differences in properties were included in the same group. for example, hard metals like copper and silver were included along with soft metals like sodium and potassium. No proper position could be given to the element hydrogen.

2) Limitations of the Mendeleev periodic table are listed below :-

• Elements with large differences in properties were included in the same group.
• No proper position could be given to the element hydrogen.
• The increasing order of atomic mass was not strictly followed throughout.