Newlands’ classification of elements did not include noble gases.
Law of octaves
In 1866 an English scientist John Newlands arranged the elements to increase atomic masses, starting from the hydrogen having the lowest atomic mass to the 56th element named thorium having the highest atomic mass among the elements discovered at that time. It was found that every eighth element possessed properties similar to that of the first. Sodium is the eighth element after Lithium possessing properties similar to one another. Similarly, beryllium and magnesium resemble each other.
In Newland’s octaves, the noble gases were missing because these elements were not known at that time. Newland’s arrangement of elements will not fit the musical scale with the eight-note that resembles the first one if the noble gases are included in Newland’s octaves.