George Washington Carver went on to become a chemist.
The suffix in the sentence is "ist"
Chem is the root word
-ist is a suffix, which means "a person who does an action" and can be used to change a word into a profession.
Other examples of the words with the suffix -ist:
Art = Artist (who creates art)
Tour = Tourist (who is on a tour)
Guitar = Guitarist (who plays guitar)
