Question

What is the Law of octave?

Answer 1

Hint: The law of octaves was given by Newland who arranged the elements in increasing order of their atomic weight and found that the physical and chemical properties of elements repeat after every 8th element.

Complete answer:
Law of octaves was proposed and given by the English chemist J.A.R. Newlands in 1865. According to this law, if the chemical elements are arranged in the order of increasing atomic weight, those with similar physical and chemical properties occur after each interval of eight elements. This was one of the earlier attempts at framing periodic patterns in the properties of the elements and helped in later developments of the periodic law.
However, this method of classifying elements had a lot of resistance in the scientific community due to its many limitations that include the following points:
-Several elements were fit into the same slots in Newland’s periodic classification. For example, cobalt and nickel were placed in the same slot.
-Elements with different properties were grouped together. For example, the halogens were grouped with some metals such as cobalt, nickel, and platinum.
-The law of octaves is only valid up to calcium.
-The elements that were discovered later could not be fit into the octave pattern.
Therefore, the law of octave laid the foundation for the build-up of the periodic table but it did not leave any room for discoveries of new elements.

Note:
At the time Newland gave the octave law, there were about 56 elements discovered and thus he assumed that no more than 56 elements would be discovered. However, Mendeleev predicted and left some gaps for undiscovered elements in the periodic table proposed by him which later came to be true.