Question

Increasing order of atomic weights was violated in the case of

Answer 1

Answer:

The original periodic law was violated in case of 4 pairs of elements . The element of higher atomic weight was placed before the elements having lower atomic mass.

Explanation:

Answer 2

Explanation:

In Mendeleeff ‘s modern periodic table , elements have been arranged in the increasing order of their atomic numbers.With the replacement of atomic mass by atomic number as the basis of classification, two main defects of original periodic table disappears. These are,

1) Anamalous pair –

1) Anamalous pair –The original periodic law was violated in case of 4 pairs of elements . The element of higher atomic weight was placed before the elements having lower atomic mass.

2) Position of isotopes –

Atoms having same atomic number but different atomic masses are called isotopes .

The isotopes of same element will be given different position if atomic mass is the basis of classification. In modern periodic table isotopes are placed in one position. So this problem is removed.

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