What is meant by Newlands law of octaves?

Explanation

(1) Newland's law of octaves states that when the elements are arranged in the order of their increasing atomic masses, every eighth element has properties similar to those of the first .
(2) Illustration : If the first 21 elements, except inert gases, are arranged in the order of their increasing atomic masses we have octaves as given below :
It is found that Na is the eighth from Li and both of them have similar properties. Simlarly the elements , in the following pairs show similar properties : C and Si, Na and K, Mg and Ca, F and CI.