What scientist studied x ray spectra of the elements to reveal their periodicity?

The scientist who studied X-ray spectra of the elements to reveal their periodicity was Moseley. Henry Moseley conducted experiments in the early 20th century that demonstrated a systematic relationship between the wavelength of X-rays emitted by elements and their atomic number, rather than their Atomic Mass. This work provided a clearer understanding of the Periodic Table and led to the reordering of elements based on atomic number, which is a foundational concept in modern chemistry.