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प्रश्न
Give a reason for the following:
Mendeleev's contributions to the periodic table laid the foundation for the Modern Periodic Table.
उत्तर
Mendeleev found that there was a close relation between atomic weights and properties of elements. He also found that when elements are arranged in increasing order of their atomic weights, the properties repeat at regular intervals.
He even left some gaps for the elements not know at that time whose properties resembled the neighbouring elements. Predicted properties of eKa Aluminium (before discovery) are exactly the same as actual properties of gallium element (after discovery).
Moreover, he arranged all the 63 elements known at that time. Still, there were many drawbacks in this periodic table, but Mendeleeff laid the foundation of modern periodic table.
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संबंधित प्रश्न
Use Mendeleev’s Periodic Table to predict the formulae for the oxides of the following elements:
K, C, Al, Si, Ba.
Element X forms a chloride with the formula XCl2, which is a solid with a high melting point. X would most likely be in the same group of the Periodic Table as
(a) Write its electronic configuration and determine its valency.
(b) Is it more reactive or less reactive than Ca (atomic number 20)? Justify your answer giving reason.
(c) Is it a metal or a non-metal?
(d) Write the formula of its oxide.
Write the merits of Mendeleev’s periodic table.
State Mendeleev's periodic law.
How many elements were known at the time of Mendeleev's classification of elements?
What are the demerits of Mendeleev’s periodic table?
What physical and chemical properties of elements did Mendeleev consider in compiling the periodic table?
Properties of the elements are given below. Where would you locate the following elements in the periodic table?
- A soft metal stored under kerosene
- An element with variable (more than one) valency stored under water.
- An element which is tetravalent and forms the basis of organic chemistry
- An element which is an inert gas with atomic number 2
- An element whose thin oxide layer is used to make other elements corrosion resistant by the process of “ anodising”
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?
