How did the work of Dmitri Mendeleev differ from that of John Newlands in the development of the periodic table?

Mendeleev left gaps in his periodic table for elements that had not yet been discovered. He used patterns in the known elements’ properties to predict what those missing elements would be like, and later discoveries supported his predictions. Newlands arranged elements by increasing atomic mass and observed repeating patterns, but he did not make these successful predictions of undiscovered elements.

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