Atomic number is considered to be a more appropriate parameter than atomic mass for classification of elements in a periodic table. Why?

Explanation

Atomic number is more important than atomic mass because: Atomic number z indicates the number of protons and electrons in an atom of the element. All the physical and chemical properties of elements are due to arrangement of electrons (electronic configuration), which depends on the atomic number. Proton .number. is a characteristic property of an element which remains same even when its atom is charged and in all the isotopes of an element.
Atomic number is different for different elements and increases steadily by one unlike atomic mass.