Question

Who proposed that atomic number is the more fundamental property for classifying elements?

Answer 1

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This was the discovery made by Henry Gwyn-Jefferies Moseley. He found that certain lines in the X-ray spectrum of each element moved the same amount each time you increased the atomic number by one.

Answer 2

Henry Moseley

The scientist who first of all showed that the atomic number is more fundamental property of an element than its atomic mass was Henry Moseley. He is best known for the Moseley's Law and contributions to Physics.