Glenn Seaborg didn't actually *make* the periodic table. He contributed significantly to its expansion and understanding.

Here's the breakdown:

* Dmitri Mendeleev is credited with creating the first periodic table in 1869.

* Seaborg's contributions came in the 1940s and 50s. He was a key figure in the discovery and characterization of several transuranium elements (elements heavier than uranium). These discoveries led to the placement of these new elements in the periodic table, expanding its structure.

So, while Seaborg didn't create the periodic table, he played a crucial role in expanding its scope and understanding by discovering and characterizing new elements.