give two defects of mendeleev's periodic table
Answers
Explanation:
Following are the defects in the Mendeleev periodic table:
Anomalous Pairs. The following pairs of elements don't follow the follow Mendeleev's Principles: ...
Grouping of chemically dissimilar elements. ...
Position of Isotopes. ...
Electronic arrangement. ...
Separation of chemically similar elements. ...
The position of hydrogen.
Answer:
Following are the defects in the Mendeleev periodic table:
Anomalous Pairs
The following pairs of elements don’t follow the follow Mendeleev’s Principles:
Cobalt (58.9) with a higher atomic mass precedes Nickel (58.6) in the periodic table.
Tellurium (127.6) with a higher atomic mass than Iodine (126.9) precedes it in the periodic table.
Grouping of chemically dissimilar elements
Elements such as Copper and Silver bear no resemblance with the alkali metals, but they have been placed together in the first group.
Position of Isotopes
According to Mendeleev’s Periodic Law, isotopes of an element must be given separate places in the periodic table because they have different atomic masses.
Electronic arrangement
It does not explain the electronic arrangement of elements.
Separation of chemically similar elements
Elements that are chemically similar such as Gold and Platinum have been placed in separate groups.
The position of hydrogen
Hydrogen was not given a fixed position because it was considered in Group IA as well as in Group VIIA.
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