Question

Limitations of Newland's Octave rule.

Answer 1

Limitations of Newland's Octave Rule:-

• Inert gases were not discovered at that time. So, as inert gases were introduced, these elements came to the 9th position, without remaining at the 8th position.

• This rule was not applicable for all the discovered elements at that time. It was applicable to only lighter elements having atomic masses upto 40 u, i.e., upto calcium. After calcium, the first and the eighth element did not have similar properties.

For example, chromium (Cr) and yttrium (Y) are the first and the eighth element placed in the same column but they have entirely different properties.

• Some similar elements have been separated from one another while some dissimilar elements have been placed in the same column.

For example, iron (Fe) resembles cobalt (Co) and nickel (Ni) but has been placed far away from these elements.

Answer 2

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$\sf\underline{Limitations \: of \: Newland's \: Octave \: rule.}$

→ Law of Octaves only applicable upto calcium and after calcium every 8th did not possess properties similar to that of the first.

→ At the time of Newlands' only 56 elements were existed in nature and Newlands'assume that no more elements will be discovered the future.

→ But, later on , several new elements were discovered, whose properties did not fit into the law of octaves.

→ One important demerit of Newlands' law that he adjusted two elements in the same slot such as Cobalt and nickel [ Co and Ni ] .

→ With the discovery of noble gases the law of octaves become irrelevant.

→ Newlands'law of Octaves worked well with lighter elements only.