Why couldn't Mendeleev organize the entire table during his research?

Mendeleev faced challenges in organizing the entire Periodic Table due to the limited number of known elements at the time and the lack of understanding of atomic structure. Some elements had not yet been discovered, and he had to leave gaps for these unknown elements, predicting their properties based on the patterns he observed. Additionally, discrepancies in atomic weights led to difficulties in placing certain elements accurately, prompting him to prioritize chemical properties over Atomic Mass in some cases.