Characteristic Integers - Marc'Antonio Mazzoleni collection.

Excerpt from the concluding paragraph of Moseley’s paper, “The High-Frequency Spectra of the Elements. Part II.”

Between 1912 and 1913, Henry and Lawrence Bragg demonstrated that, in addition to continuum X-ray spectra, there also exist discrete characteristic spectra, where each line corresponds to the emission of a specific energy. This finding indicated that some X-ray properties are determined by atomic structure. In 1913, through a brilliant series of experiments, Moseley discovered that the frequencies of corresponding lines in X-ray spectra are proportional to the squares of integer numbers, called atomic numbers. Later, in 1914, Moseley published a second paper in which he concluded that the atomic number represents the number of positive charges in the atomic nucleus. This relationship, now known as Moseley’s law, was a fundamental breakthrough in understanding atomic structure.

Britannica — Henry Moseley.
Moseley (1913) — The high-frequency spectra of the elements.
Moseley (1914) — The high-frequency spectra of the elements. Part II.

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