<P> Meyer and Mendeleev are considered by some historians of science to be the co-creators of the periodic table, but Mendeleev's accurate prediction of the qualities of undiscovered elements enables him to have the larger share of the credit . </P> <P> In 1864, the English chemist William Odling also drew up a table that was remarkably similar to the table produced by Mendeleev . Odling overcame the tellurium - iodine problem and even managed to get thallium, lead, mercury and platinum into the right groups, which is something that Mendeleev failed to do at his first attempt . Odling failed to achieve recognition, however, since it is suspected that he, as Secretary of the Chemical Society of London, was instrumental in discrediting Newlands' earlier work on the periodic table . </P> <P> In 1914, a year before he was killed in action at Gallipoli, the English physicist Henry Moseley found a relationship between the X-ray wavelength of an element and its atomic number . He was then able to re-sequence the periodic table by nuclear charge, rather than by atomic weight . Before this discovery, atomic numbers were sequential numbers based on an element's atomic weight . Moseley's discovery showed that atomic numbers were in fact based upon experimental measurements . </P> <P> Using information about their X-ray wavelengths, Moseley placed argon (with an atomic number Z = 18) before potassium (Z = 19), despite the fact that argon's atomic weight of 39.9 is greater than the atomic weight of potassium (39.1). The new order was in agreement with the chemical properties of these elements, since argon is a noble gas and potassium is an alkali metal . Similarly, Moseley placed cobalt before nickel and was able to explain that tellurium occurs before iodine, without revising the experimental atomic weight of tellurium, as had been proposed by Mendeleev . </P>

Who created the periodic table by atomic number