Mendeleev was the first scientist to arrange the known elements into a table. Mendeleev decided to arrange the known elements by atomic weight and allowed Mendeleev to predict the discovery to new elements by finding and placing gaps in the table where there was a jump in atomic weight.
Moseley used the x-ray wave lengths of the elements are arranged them in a table using the experimental data. This new technique resulted in some differences in the two tables like argon and potassium switching paces. cobalt was placed before nickle and tellurium was before iodine.
