State and give one example for Dobereiner's law of triads and Newland's law of octaves.

Explanation

Dobereiner's law of triads : When a group of three elements of similar properties are arranged in increasing order of their atomic weight the atomic weight of the middle element is an arithmetic mean of the other two elements e.g.,
`{:("Element","Atomic weight"),(Li,7),(Na,23),(K,39):}`
Newland's law of octaves: When elements are arranged in the increasing order of their atomic weights, every eighth element has properties similar to the first element analogous to every eighth note that resembles the first in octaves of music.
`{:(Li,Be,B,C,N,O,F),(Na,Mg,Al,Si,P,S,Cl),(K,Ca, , , ,,):}`.