Question
Mendeleev’s periodic table and Modern Periodic table.
✓
Answer
| Mendeleev’s Periodic Table | Modern 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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