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प्रश्न
Describe two anomalies of Mendeleev's periodic classification of elements.
उत्तर
Anomalies of Mendeleev's periodic classification of elements:
1. Mendeleev's periodic classification of elements could not explain the position of isotopes in the periodic table: Since, isotopes of the same metal have similar chemical properties but different in their atomic masses. So, the isotopes of the same element should be given different place in periodic table as Mendeleev's periodic table was arranged in increasing order of their atomic masses. However, isotopes were not given separate place in his periodic table.
2.Mendeleev's periodic classification of elements could not assign a proper place for the element,hydrogen. Since, hydrogen resembled both alkali metals and halogens in some of the properties.
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संबंधित प्रश्न
The element eka-silicon in Mendeleev’s periodic table is known as ………… in the modern periodic table.
In the classification of the them known elements, Mendeleev was guided by two factors. What are those two factors?
Name two elements whose properties were predicted on the basis fo their positions in Mendeleev's periodic table.
The three elements predicted by Mendeleev from the gaps in his periodic table were known as eka-boron, eka-aluminimum and eka-silicon. What names were given to these elements when they were discovered later on?
What name were given by Mendeleev to the then undiscovered element scandium.
What name were given by Mendeleev to the then undiscovered element gallium?
Why did Mendeleev leave some gaps in his periodic table?
Two elements in the same position : demerit of Newland's octaves : : place for Isotopes : _______
Match the columns.
| Column A | Column B |
| 1) Eka-aluminium | a) Scandium |
| 2) Eka-Silicon | b) Gallium |
| 3) Eka- boron | c) Germanium |
| d) Beryllium |
Match the column:
| Column ‘A’ | Column ‘B’ |
| Alkali metals | (a) Group 18 |
| Halogens | (b) Group 1 |
| Noble gases | (c) Group 17 |
