and predicted the existence of another row to the table which were the actinides which were some of the heaviest in atomic weight. Some people dismissed Mendeleev for predicting that there would be more elements, but he was proven to be correct when Ga (gallium) and Ge (germanium) were found in 1875 and 1886 respectively, fitting perfectly into the two missing spaces.

By using Sanskrit prefixes to name "missing" elements, Mendeleev may