Question

Why isotopes cant be inserted in mendaleevs periodic table???

Answer 1

Isotopes are the atoms of the same element having different atomic masses. Therefore, according to Mendeleev’s classification these should be placed at different places depending upon their atomic masses. For example, hydrogen isotopes with atomic masses 1,2 and 3 should be placed at three places. However, isotopes have not been given separate places in the periodic table because of their similar properties.

The isotopes of an element have no place in the periodic table.

The failure of Mendeleev’s periodic law to explain the wrong order of the atomic masses of some elements and the position of isotopes led scientists working in this field to conclude that atomic masses cannot be the basis for the classification of elements. There must be a more fundamental property of elements which can be the basis of classification.