Mendeleev predicted the existence of few undiscovered elements based on his periodic table.
True
When Mendeleev proposed his periodic table, he noted gaps in the table and predicted that unknown elements exist with properties appropriate to fill those gaps. The four predicted elements- eka-boron (Eb ), eka-aluminium (Ea ), eka-manganese ( Em) and eka-silicon (Es ) proved to be good predictors of the properties of scandium, gallium, technetium and germanium respectively, with each fills the spot in the periodic table assigned by Mendeleev.