Differentiate between the arrangement of elements in Mendeleev’s periodic table and Modern periodic table.

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1 Answers

Mendeleev’s periodic table                                      Modern periodic table.                                                                                                      
1 The elements were arranged according to  increasing atomic masses.                    The elements were arranged according to increasing atomic masses.                                    
2 Position of isotopes was not justified.                           There was no problem in the placing of isotopes.                                                                
3 Position of hydrogen was not justified because it resembles both with alkali metals and halogens.                   Hydrogen has been given a unique position due to its resemblance with alkalis and halogens.                          

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