Question

Why is the periodic table not arranged by atomic weight and instead arranged by atomic number?

Answer 1

The chemical properties are mainly dependent on the electrons, or in some cases the charge of the protons, which is independent of the number of neutrons.So,they are arranged by increasing atomic number…

Answer 2

• Atomic weight doesn't increase in a constant manner with respect to elements increase in atomic number.
• Where as while taking about atomic number it increases in a specific manner so it's easy to arrange a periodic table .

At before Duberinor,Mendeleev tried to use atomic weight but they failed .