Who arranged the modern periodic table? How is it arranged?
Dmitri Mendeleev - arranged the PT through experimentation.
I have answered a similar question, so you can see a more detailed answer there: https://socratic.org/questions/how-were-the-elements-arranged-in-dmitri-mendeleev-s-periodic-table#337149
The Periodic Table was arranged by a Russian chemist, named Dmitri Mendeleev in 1869.
Only a handful of elements were discovered so he didn't have a lot to work with, but what he did was go through each element's property, grouping those with similar results together. Those groups became families.
Now that more elements are discovered, scientists add on to Mendeleev's table. Like recently, Uus, is thought to be a Halogen.
Hope this helps :)