Originally Posted by potter

Where did you get this idea that they say/think they absolutely know for sure how many elements there are? The periodic table consists of the known elements, there might be plenty more out there in the universe we don't know about yet - and when we find them we add them to the periodic table. There's plenty of "gaps" in the table as it stands right now that scientists believe we'll eventually "fill in" as we find the elements.

All of this information is freely available online, and it's something you were likely even taught in grade school. You should probably read the wiki page on simple things like this before asking relatively dumb questions: http://en.wikipedia.org/wiki/Periodic_table

In fact, humans can even create new elements to add to the periodic table (Since the periodic table is a list of elements whose number is the number of protons in their nucleus).

Meet 115, the Newest Element on the Periodic Table

http://news.nationalgeographic.com/n...eriodic-table/


-- Hope that helps