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.
1 Guion Bluford, 1983, became the first black astronaut to travel in space; Mae Jemison, 1992, became the first black female astronaut. 2  Frederick D. Gregory, 1998, was the first African-American shuttle commander.