Who discovered the periodic table of element?
Dmitri Mendeleev, although he did it differently we than it is
right now. He pridected elements, and now, they've been discovered.
Some people discovered elements Mendeleev didn't predict. Most of
them were radioactive, like rutherfordium. (Of course, that element
was synthetic. There are only 92 natural elements.) Mendeleev used
different symbols than we do now, e.g. yttrium was Yt. The elements
Mendeleev predicted were gallium, germanium, and scandium.