* Scandium (Sc)
* Gallium (Ga)
* Germanium (Ge)
He did this based on the following reasoning:
1. Periodic Law: Mendeleev's periodic law stated that the properties of elements are a periodic function of their atomic masses. He noticed gaps in the table where elements with certain expected properties should exist.
2. Predicting Properties: Mendeleev boldly predicted the existence and properties of these missing elements, which he named eka-boron (Sc), eka-aluminum (Ga), and eka-silicon (Ge).
3. Later Discovery: These elements were later discovered and their properties closely matched Mendeleev's predictions, providing strong evidence for the validity of his periodic table.
Mendeleev's willingness to leave spaces and predict the existence of undiscovered elements is a testament to his brilliance and the power of the periodic table.
