The discovery of hafnium and the brief history of industrial development
Following the X-ray study of elements by British physicist mosley, there are 16 elements to be found between barium and tantalum. In addition to element 61 and element 72, the remaining 14 elements have been found, and they belong to today's lanthanum, which was thought to be the rare earth element.
In 1914, some claimed to have discovered element 72, of which Georges Urbain claimed that he discovered element 72 in the rare earth element in 1907 and published his findings in 1911. But his conclusions were overturned after a long debate.
In 1913, the Danish physicist Bohr put forward the quantum theory of atomic structure. Then the electron configuration theory was put forward between 1921 and 1922. Bohr believes that according to his theory, element 72 does not belong to rare earth elements, and zirconium is an element of kin. That is to say, element 72 does not appear in minerals from rare earth elements, but should be found in minerals containing zirconium and titanium.
In early 1923, based on Bohr atomic theory, mo weasley X-ray spectra and friedrich Leon panetta chemical parameters of the theory, some physicists and chemists think element 72 and zirconium properties are similar, and thus do not belong to the rare earth elements.