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Explain the defects of Modern periodic table .
Class - 10th
Chapter - Periodic classification of elements.
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Answers
Answer:
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. It does not explain the electronic arrangement of elements. Elements that are chemically similar such as Gold and Platinum have been placed in separate groups.
Explanation:
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★ QuestioN :
Explain the defects of Modern periodic table .
★ ANswer :
The defects of modern periodic table are :
• Position of Hydrogen : Position of Hydrogen, is still controversial in the modern periodic table . If we look at the structure of Hydrogen, then it has one electron in its outermost shell similar like alkali metals. But if we see bonding and other features of hydrogen, then it behaves like Group 17 elements similar like Halogens. So for now Hydrogen is placed on the top of periodic table not specifically in any group or period. Instead it is kept seperately.
• Positioning of unordered pair :: According to a general trend in modern periodic table, ionisation enthalpy increases as we go from right to left in a period. But at some places the ionisation enthalpy of preceding elements fpr example, Beryllium has higher ionisation enthalpy than Boron.
• Hydration Enthalpy :: It is a general trend in modern periodic table, that hydration and enthalpy increases as we go down the group. But for alkaline metals, Lithium being the first element in Group 1, has highest hydration enthalpy than other elements in that group.
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★ More to know :-
• Modern Periodic Law : Atomic Numbers are the function of physical and chemical properties of elements.
• Mendeleev Periodic Law : Atomic Mass is the function of physical and chemical properties of elements.
• Dobreniers Triad : In this classification the average of sum of atomic mass of first and third element is equal to the atomic mass of second element.
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