When did John Newlands bring in the "Law of the Octaves"?

John Alexander Reina Newlands (26 November 1837 – 29 July 1898) was a British chemist, who arranged the then known elements in the order of increasing atomic masses in 1865. He started with the element having the lowest atomic mass (hydrogen) and ended at thorium which was the 56 element. He found that every eighth element had properties similar to that of the first. He compared this to the octaves found in music. Therefore, he called it the 'Law of Octaves'. It is known as 'Newlands' Law of Octaves'. In Newlands' Octaves, the properties of lithium and sodium were found to be the same. Sodium is the eighth element after lithium. Similarly, beryllium and magnesium resemble each other.

Some demerits of Newlands' Law of Octaves,

● It was found that the Law of Octaves was applicable only upto Calcium, as after calcium every eighth element did not possess properties similar to that of the first.

● It was assumed by Newlands that only 56 elements existed in nature and no more elements would be discovered in the future. But, later on, several new elements were discovered, whose properties did not fit into the Law of Octaves.

● In order to fit elements into his Table, Newlands adjusted two elements in the same slot, but also put some unlike elements under the same note.

Thus, Newlands' Law of Octaves worked well with lighter elements only.