In the periodic table, the maximum chemical reactivity is at the extreme left (alkali metals) and extreme right (halogens). Which properties of these two groups are responsible for this?
- Least ionisation enthalpy on the left and highest negative electron gain enthalpy on the right.
- Non-metallic character on the left and metallic character on the right.
- High atomic radii on the left and small atomic radii on the right.
- Highest electronegativity on the left and least electronegativity on the right.
The Correct Option is A
Solution and Explanation
Top Questions on Classification of elements and periodicity in properties
Match List I with List II.
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In which of the following reactions of H$_2$O$_2$ acts as an oxidizing agent (either in acidic, alkaline, or neutral medium)?
% Given Reactions
(i) \( 2Fe^{2+} + H_2O_2 \rightarrow \)
(ii) \( 2MnO_4^- + 6H^+ + 5H_2O_2 \rightarrow \)
(iii) \( I_2 + H_2O_2 + 2OH^- \rightarrow \)
(iv) \( Mn^{2+} + H_2O_2 \rightarrow \)
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- Classification of elements and periodicity in properties
- A metalloid is:
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- A pair of isoelectronic species having a bond order of one is:
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- Classification of elements and periodicity in properties
- Which of the following statements related to lanthanoids is incorrect?
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- Classification of elements and periodicity in properties
Notes on Classification of elements and periodicity in properties
Concepts Used:
Classification of Elements & Periodicity in Properties
Since many elements were being discovered in the 19th century and the study of these elements individually was proving difficult, classification of elements was made necessary.
Classification by Johann Dobereiner - German chemist Johann Dobereiner classified certain elements on the basis of their similar properties in the groups of continuing - three elements each. These groups were called ‘triads’. In every triad, the atomic weight of the middle element was equal to the average of the atomic weights of the first and third elements.
Newlands Law of Octaves - The elements were arranged in increasing order of their atomic weights and found that every 8th element shows similarity with the 1st element.
Mendeleev’s Periodic Table - The arrangement of all 63 elements in rows or columns in order of their atomic weight was made by Mendeleev. He left some space for corresponding elements in his periodic table which were not even discovered till then. Although he predicted the properties of those elements through his periodic classification of elements.
Modern Periodic Law - The properties of the elements of the modern periodic law are periodic functions of their atomic numbers.