But around a decade later, the Danish physicist Niels Bohr - who used quantum theory to develop a model of the atom in which electrons orbit the nucleus - predicted that element 72 would be among the transition metals, and closer to zirconium (element 40). The French chemist Georges Urbain originally proposed, in 1911, that element 72 belonged among the periodic table’s rare earth elements, and named it celtium. The battle behind the periodic table’s latest additionsīut the discovery (and naming) of element 72, hafnium, was anything but straightforward. Moseley’s work provided both a more accurate ‘gap map’ and a method for identifying elements from the spectra produced by exposing candidate elements to X-rays. By 1914, just seven gaps remained.Ī breakthrough occurred in 1913, when Henry Moseley, a British physicist, showed that elements could be arranged by their atomic number, or their number of protons. For example, the predicted ‘element 68’, gallium, was identified a few years later, in 1875. To make the table work, he had to leave gaps where as-yet undiscovered elements might be placed. When Mendeleev devised the periodic table’s rough form, he started with 63 known elements. Remarkably, both Mendeleev’s and Lothar Meyer’s schemes were based on elements’ subatomic structure - several decades before the discovery of electrons and protons. Mendeleev’s contribution, and that of the German chemist Julius Lothar Meyer, working independently, provided an order for the elements, along with criteria for classifying them into neat groups. Hafnium also came to represent a hard-won victory against those determined to undermine evidence-based discovery.ĭmitri Mendeleev’s periodic table of elements, created in 1869, emerged from the realization that chemical elements such as oxygen and hydrogen share certain relationships. The find secured not only the periodic table’s legacy but also the future of chemistry.

The element was identified by two scientists working in Copenhagen: Dutch physicist Dirk Coster and Hungarian chemist Georg von Hevesy. But hafnium’s discovery, which was reported in Nature a century ago this week 1, was of disproportionate importance. It’s a greyish metal and is commonly used as a neutron absorber in the control rods of nuclear power plants and nuclear submarines, and as an insulator in computer chips. It’s not your explosive sodium, shimmering mercury or stinky sulfur. Hafnium isn’t a particularly remarkable element. Hafnium is a transition metal named after the Latin name for Copenhagen (Hafnia), where the element was discovered.

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