Newland's law of octaves states thatif the chemical elements are arranged according to increasing atomic weight, those with similar physical and chemical properties occur after each interval of seven elements.
Newland compared the similarity between the elements to the octaves of music where every eight note is comparable to the first.
This was the first attempt at assigning an atomic number to each element.
Sodium is the eighth element after lithium similarly beryllium and magnesium resemble each other.
Therefore, Newland's law of octaves said that the eighth element had properties similar to that of the first when the elements are arranged in the increasing order of their atomic weights.