Question

State Newlands law of octaves. Give one of its limitations.

Answer 1

Hint: You should know that a scientist called John Newlands put forward his law of octaves in 1864. Now try to recall the generalized statement, and answer the question by yourself.

Complete step by step answer:
As we know Newland was one of the first one to detect a periodic pattern in the properties of the elements and anticipated later developments of the periodic law.

In simple words Newland stated that:
So, basically if the elements were arranged in the order of their relative atomic masses with a few transpositions, the number of similar elements differs by multiples of seven. Therefore, in the nitrogen group, phosphorus is the seventh element after nitrogen and arsenic is the fourteenth element after phosphorus as it is antimony after arsenic. So this was a brief explanation about the law of octaves.

Newland recognized that with every seventh element, the 8^th element seemed to be similar to the 1^st of the previous seventh element. He also recognized that the groups had more than 3 elements and as we know, he combined both metals and nonmetals in the same group.

Limitations of Newland’s law of octave:
1) It is observed that the observation made by Newland does not hold well for those elements which were lying beyond calcium. After calcium every eight elements did not possess properties similar to the first element.
2) The elements which were discovered later could not be fitted into the law of octaves.
3) As we know, after the discovery of Noble gases, it became difficult to fit them in Newlands’s periodic table.

Note: As we know iron possessing similar properties as cobalt and nickel, is placed far away from these elements. Remember that Newland’s law of octaves can be obeyed well by the lighter elements only.