In 1869, just five years after John Newlands put forward his law of octaves, a Russian chemist called Dmitri Mendeleev published a periodic table. Mendeleev also arranged the elements known at the time in order of relative atomic mass, but he did some other things that made his table much more successful.
i hope this helps in some way!
Identifies the number of protons a single atom of the element contains.
The atomic number helps people identify elements according to the number of protons one atom of the element has. It essentially defines the element
