Scandium was isolated as the oxide in 1879 by Lars Fredrick Nilson (1840-1899)and was shown by Cleve to be identical with the ekaboron (Eb) predicted by Dmitri Mendeleev.
Mendeleev and the Periodic Table
Mendeleev published the first Periodic Table of the Atomic Elements in 1869. Noting the gaps in the table, he predicted the existence of yet to be discovered elements. The predicted element ekaboron, filled the place in Mendeleev''s Table where scandium is located.