page_title: Henry Moseley
section_title: Death and aftermath
hierarchical_section_title: Henry Moseley / Death and aftermath
caption_attribution_description: English: National Chemical Landmark: Clarendon Laboratory where H.G.J. Moseley (1887-1915) completed his pioneering studies on the frequencies of X-rays emitted from the elements. His work established the concept of atomic number and helped reveal the structure of the atom. He predicted several new elements and laid the ground for a major tool in chemical analysis. Clarendon Laboratory, Sherrington Road, Oxford OX1 3PU Plaque erected 24 September 2007 by the Royal Society of Chemistry
context_page_description: Henry Gwyn Jeffreys Moseley was an English physicist, whose contribution to the science of physics was the justification from physical laws of the previous empirical and chemical concept of the atomic number. This stemmed from his development of Moseley's law in X-ray spectra.
  Moseley's law advanced atomic physics, nuclear physics and quantum physics by providing the first experimental evidence in favour of Niels Bohr's theory, aside from the hydrogen atom spectrum which the Bohr theory was designed to reproduce. That theory refined Ernest Rutherford's and Antonius van den Broek's model, which proposed that the atom contains in its nucleus a number of positive nuclear charges that is equal to its number in the periodic table. This remains the accepted model today.
  When World War I broke out in Western Europe, Moseley left his research work at the University of Oxford behind to volunteer for the Royal Engineers of the British Army. Moseley was assigned to the force of British Empire soldiers that invaded the region of Gallipoli, Turkey, in April 1915, as a telecommunications officer. Moseley was shot and killed during the Battle of Gallipoli on 10 August 1915, at the age of 27.
context_section_description: Sometime in the first half of 1914, Moseley resigned from his position at Manchester, with plans to return to Oxford and continue his physics research there. However, World War I broke out in August 1914, and Moseley turned down this job offer to instead enlist with the Royal Engineers of the British Army. His family and friends tried to persuade him not to join, but he thought it was his duty. Moseley served as a technical officer in communications during the Battle of Gallipoli, in Turkey, beginning in April 1915, where he was killed in action on 10 August 1915. Moseley was shot in the head by a Turkish sniper while in the act of telephoning a military order.
  Only twenty-seven years old at the time of his death, Moseley could, in the opinion of some scientists, have contributed much to the knowledge of atomic structure had he survived. Niels Bohr said in 1962 that Rutherford's work "was not taken seriously at all" and that the "great change came from Moseley."
  Robert Millikan wrote, "In a research which is destined to rank as one of the dozen most brilliant in conception, skillful in execution, and illuminating in results in the history of science, a young man twenty-six years old threw open the windows through which we can glimpse the sub-atomic world with a definiteness and certainty never dreamed of before. Had the European War had no other result than the snuffing out of this young life, that alone would make it one of the most hideous and most irreparable crimes in history."
  George Sarton wrote, "His fame was already established on such a secure foundation that his memory will be green forever. He is one of the immortals of science, and though he would have made many other additions to our knowledge if his life had been spared, the contributions already credited to him were of such fundamental significance, that the probability of his surpassing himself was extremely small. It is very probable that however long his life, he would have been chiefly remembered because of the 'Moseley law' which he published at the age of twenty-six."
  Isaac Asimov wrote, "In view of what he [Moseley] might still have accomplished … his death might well have been the most costly single death of the War to mankind generally." Isaac Asimov also speculated that, in the event that he had not been killed while in the service of the British Empire, Moseley might very well have been awarded the Nobel Prize in Physics in 1916, which, along with the prize for chemistry, was not awarded to anyone that year. Additional credence is given to this idea by noting the recipients of the Nobel Prize in Physics in the two preceding years, 1914 and 1915, and in the following year, 1917. In 1914, Max von Laue of Germany won the Nobel Prize in Physics for his discovery of the diffraction of X-rays by crystals, which was a crucial step towards the invention of X-ray spectroscopy. Then, in 1915, William Henry Bragg and William Lawrence Bragg, a British father-son pair, shared this Nobel Prize for their discoveries in the reverse problem — determining the structure of crystals using X-rays (Robert Charles Bragg, William Henry Bragg's other son, had also been killed at Gallipoli, on 2 September 1915). Next, Moseley used the diffraction of X-rays by known crystals in measuring the X-ray spectra of metals. This was the first use of X-ray spectroscopy and also one more step towards the creation of X-ray crystallography. In addition, Moseley's methods and analyses substantially supported the concept of atomic number, placing it on a firm, physics-based foundation. Moreover, Charles Barkla of Great Britain was awarded the Nobel Prize in 1917 for his experimental work in using X-ray spectroscopy in discovering the characteristic X-ray frequencies emitted by the various elements, especially the metals.  "Siegbahn, who carried on Moseley's work, received one [a Nobel Prize in Physics, in 1924]." Moseley's discoveries were thus of the same scope as those of his peers, and in addition, Moseley made the larger step of demonstrating the actual foundation of atomic numbers
caption: Blue plaque erected by the Royal Society of Chemistry on the Townsend Building of the Clarendon Laboratory at Oxford in 2007, commemorating Moseley's early 20th-century research work on X-rays emitted by elements.
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