is the following sentence true or false? Mendeleev used his periodic table to predict the properties of undiscoverd elements..

True: Mendeleev used his periodic table to predict the properties of a undiscoverd element.

True. Mendeleev is known for creating the periodic table of elements. He organized the elements based on their properties and atomic weights. By leaving gaps in the table, Mendeleev predicted the existence and properties of elements that were yet to be discovered.