A periodic table helps us organise all the elements we have discovered so far.
In it's evolution we can see more and more elements being added to it. until we reached 118 elements.
the elements from atomic number 87 start showing radioactivity, which makes them harder to find naturally as compared to the ones that can be seen before these in the periodic table
elements beyond 118 are SO unstable that if you want to study one, you have to manufacture your own
(That is because up until these elements, we were using up only 4 atomic orbitals, namely s,p,d and f. but elements beyond 118 will have a g orbital, which is very unstable)
The most fascinating thing about our modern periodic table is the periodic trends that can be seen. these trends include Electronegativity, Atomic Size, Stability, and much more. They tell us that this arrangement of elements is perfect!