How did John Newlands’s law of octaves compare with Mendeleev’s periodic law?

John Newlands and Dmitri Mendeleev both contributed significantly to the development of the periodic law by arranging elements according to increasing atomic weight, but their approaches and impacts differed.123

• Newlands’s Law of Octaves: Proposed in 1864–1865, this generalization noted that every eighth element exhibited similar physical and chemical properties, drawing an analogy to the seven intervals of a musical scale. While it was one of the first attempts to detect a periodic pattern, it was initially controversial.123
• Mendeleev’s Periodic Law: Announced in 1869, Mendeleev’s work was more comprehensive. Beyond atomic weight, he incorporated valency and chemical properties to organize elements into groups. Mendeleev’s system was robust enough to allow him to correct existing atomic weight values and accurately predict the existence and properties of then-unknown elements like gallium, scandium, and germanium.145

Ultimately, while Newlands anticipated the concept of periodicity, Mendeleev’s systematic framework provided the foundation for modern chemical theory and gained wide international acceptance.243