An element is a chemical substance made up of a particular kind of atom and hence cannot be broken down or transformed by a chemical reaction into a different element, though it can be transmuted into another element through a nuclear reaction.
Almost 40 years separate Shirley Ann Jackson's achievement, as the first African-American woman to earn a Ph.D. in theoretical high energy physics at Massachusetts Institute of Technology, and Jedidah Isler, the first African-American woman to receive a Ph.D. in Astrophysics from Yale.
Mae Jemison becomes the first black female astronaut. 1993 - Shiela Widnall becomes the first secretary of a branch of the U.S. military when she is appointed to head the Air Force. Janet Reno becomes the first woman U.S. attorney general. 1997 - Madeleine Albright is sworn in as U.S. secretary of state.