Given the task definition and input, reply with output. Given a scientific passage and an answer, generate a question for the given answer.

Passage: The periodic table is one of the cornerstones of chemistry because it organizes all the known elements on the basis of their chemical properties. A modern version is shown in Figure 2.7 "A Modern Periodic Table". Most periodic tables provide additional data (such as atomic mass) in a box that contains each element's symbol. The elements are listed in order of atomic number. Answer: chemical properties
The periodic table is one of the cornerstones of chemistry because it organizes all the known elements on the basis of their what?