He perfected the arrangement of the periodic table?

Answer 1

The Periodic Table is more like a collaborated set of work.

Mendeleev started by arranging the elements by properties and mass.

Then, Henry Moseley arranged it by atomic number and properties, which is what we use today.

Then, Noble Gases were discovered, and those were added in.

If you look at the periodic table, it's mostly arranged by mass, too. However, it's, of course, arranged by proton number.

Answer 2

In 1869, a Russian chemist named Dmitri Mendeleev came up with a way of organizing the elements that were known at the time:

He set them out in order of atomic weight, and then grouped them into rows and columns based on their chemical and physical properties.