Question

In 1869, Mendeleev organized a periodic table based on atomic weights and arranged elements with similar properties under each other. Gaps were left for elements that were unknown at that time but Mendeleev was able to predict their properties. This was important because it supported the concept of? I know this is not history but I really need help

Answer 1

C. periodicity

Step-by-step explanation:

Answer 2

Periodic Law - the physical and chemical properties of the elements are periodic functions of their atomic numbers.

He knew they would be discovered eventually.