Question
Mendeleev’s periodic table and Modern Periodic table.

Answer

Mendeleev’s Periodic TableModern Periodic Table
(i) This table is based on the atomic mass of the elements.(i) This table is based on the atomic number of the elements.
(ii) Elements are arranged in increasing order of their mass.(ii) Elements are arranged in increasing order of their atomic number.
(iii) Mendeelev’s periodic table consists of only 63 elements.(iii) Modern Periodic table consist of 118 elements.
(iv) Mendeelev’s Periodic table is based on Mendeleev’s Periodic Law, ‘Properties of element are periodic function of their atomic masses.’(iv) Modern Periodic table is based on Modern Periodic Law,‘Properties of elements are periodic function of their atomic number.’
(v) There was no space for inert gases and radioactive isotopes.(v) The table contains all elements including inert gases and radioactive isotopes.
(vi) Some elements having similar properties were placed in different groups. Some elements in different groups were found to have similar properties.(vi) All elements placed in same group have similar properties.
(vii) Elements could not be divided into 4 blocks.(vii) Elements are divided into 4-blocks – i.e. s, p, d and f blocks.

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