That's the entire point of the periodic table - what makes it a 'periodic table' rather than 'a list of all the known (or 'found in nature') elements'. When ori

That's the entire point of the periodic table - what makes it a 'periodic table' rather than 'a list of all the known (or 'found in nature') elements'. When originally conceived it included blank spots for yet un-isolated elements and some predictions about their properties could be made. You find an element, it goes into the periodic table. Of elements.