Question

1. which of the following best explains why mendeleevs periodic table was organized according to atomic mass rather than atomic number, like modern periodic tables? atomic number is more closely related to reactivity. atomic number had not yet been discovered. atomic mass is unaffected by chemical reactions. atomic mass varies among the isotopes of an element. clear all

Explanation:

Mendeleev created his periodic table in the 19th - century. At that time, the concept of atomic number was unknown. Atomic number was discovered later which led to the modern - day organization of the periodic table.

Answer:

Atomic number had not yet been discovered.