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प्रश्न
State any three demerits of Mendeleev’s periodic table.
उत्तर
Demerits of Mendeleev’s periodic table:
- Hydrogen resembles alkali metals and halogens. So, a correct position could not be assigned to hydrogen in the periodic table.
- The position of isotopes could not be explained. Isotopes are atoms of the same element with similar chemical properties but different atomic masses. If the elements are arranged according to atomic masses, the isotopes should be placed in different groups of the periodic table.
- At certain places, an element of higher atomic mass has been placed before an element of lower atomic mass. Example: Cobalt (Co = 58.93) is placed before nickel (Ni = 58.71).
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संबंधित प्रश्न
What are the main features of Mendeleev’s periodic table?
Use Mendeleev’s Periodic Table to predict the formulae for the oxides of the following elements:
K, C, Al, Si, Ba.
On what basis did mandeleev arrange the elements in his periodic table?
State whether the following statement is true of false:
According to Mendeleev's periodic law, the properties of elements are a periodic function of their atomic numbers.
Name the Russian chemist who said that the properties of elements are a periodic function of their atomic masses.
What chemical properties of elements were used by Mendeleev in creating his periodic table?
Why did Mendel choose garden pea for his experiments? Write two reasons.
List two contrasting visible characters of garden pea Mendel used for his experiment.
Write the merits of Mendeleev’s periodic table.
Mendeleev's contributions to the concept of a periodic table laid the foundation for the Modern Periodic Table. Give reasons.
State Mendeleev's periodic law.
Use Mendeleev's Periodic Table to predict the formula of oxides of potassium, aluminum, and barium.
Name two elements whose atomic weights were corrected on the basis of their positions in Mendeleev's periodic table.
How many elements were known at the time of Mendeleev's classification of elements?
Answer the following question:
Name two elements having a single electron in their outermost shell.
State the contributions made by Mendeleev towards the periodic table.
What were the defects and anomalies in Mendeleeff's Periodic Table and how are they resolved by Moseley?
Give a reason for the following:
Mendeleev's contributions to the periodic table laid the foundation for the Modern Periodic Table.
According to Mendeleev’s periodic law, properties of elements are periodic function of their _______.
At the time of Mendeleev _______ elements were known.
According to Mendeleev’s periodic law properties of elements are ______.
While designing the periodic table, Mendeleev considered the chemical and physical properties of the elements.
State Mendeleev’s Periodic Law.
What physical and chemical properties of elements did Mendeleev consider in compiling the periodic table?
Which of the following oxide is most basic?
The total number of electrons present in the first twenty elements of the periodic table is ______
Eka-aluminium and Eka-silicon are known as ______
In Mendeléev’s Periodic Table, gaps were left for the elements to be discovered later. Which of the following elements found a place in the periodic table later
Mendeléev predicted the existence of certain elements not known at that time and named two of them as Eka-silicon and Eka-aluminium.
- Name the elements which have taken the place of these elements
- Mention the group and the period of these elements in the Modern Periodic Table.
- Classify these elements as metals, non-metals or metalloids
- How many valence electrons are present in each one of them?
Mendeleev's periodic table was based on ______.
Name the elements whose compounds formed the basis of classification in Mendeleev's periodic table. Why did Mendeleev choose these elements?
How the formulae of these compounds had helped Mendeleev in deciding the position of an element in his periodic table?
