Question

List any two observations which posed challenge to mendeleev periodic table

Answer 1

1. position of hydrogen as it showed properties same as with alkali metals and hydrogen.

2. the atomic mass of certain elements were changed.

3. as the elements were placed according to the atomic mass of elements there existed the possibility that many elements existed between two elements.

4. position of isotopes could not be explaned.

Answer 2

1. position of hydrogen as it showed properties same as with alkali metals and hydrogen.

2. the atomic mass of certain elements were changed.

3. as the elements were placed according to the atomic mass of elements there existed the possibility that many elements existed between two elements.

4. position of isotopes could not be explaned.

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