Question

Scientists improved Mendeleev’s early periodic table by _____.

using numbers of neutrons and protons to organize the elements by their properties

using atomic number instead of atomic mass to organize the elements

including physical properties of elements such as melting point and density

including chemical properties of elements such as the ability to burn or to tarnish

Answer 1

I think 1888 that’s if my teachers are correct

Answer 2

1888 it should be that thank you have a good day