The discovery that the atomic number closely corresponds to the nuclear charge of the atom is attributed to Henry Moseley. Moseley was a British physicist who conducted pioneering work on X-ray spectroscopy in the early 20th century.
In 1913, Moseley performed a series of experiments using X-ray spectroscopy to investigate the properties of different elements. He observed that when elements were bombarded with high-energy electrons, characteristic X-rays were emitted. Moseley noticed that the wavelengths of these X-rays were related to the elements' atomic numbers rather than their atomic weights, as previously believed.
Moseley's experiments provided clear evidence that the atomic number, which corresponds to the number of protons in the nucleus of an atom, was the fundamental property determining an element's chemical behavior. He developed the concept of the atomic number as a fundamental property of an element, leading to the reorganization of the periodic table based on atomic number rather than atomic weight.
Tragically, Moseley's promising scientific career was cut short when he lost his life during World War I while serving in the Gallipoli Campaign. Nonetheless, his discoveries and contributions to atomic physics have had a lasting impact on our understanding of the atomic structure and the development of the modern periodic table.