<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> 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>
who redefined the periodic table as being organized by atomic number not atomic weight
who redefined the periodic table as being organized by atomic number not atomic weight
English physicist Henry Moseley
English physicist Henry Moseley