Last night saw the series finale of AMC’s hit show Breaking Bad, about a meek chemistry teacher who, after being diagnosed with cancer, goes on to become a crystal meth-making drug kingpin (well, that’s the simplified version).

During the five seasons of the show, audiences have gotten to see a lot of chemistry, but how accurate has the science been on Breaking Bad? The folks at Bytesize Science spoke to Donna Nelson, Ph.D., an organic chemistry professor who works with series creator Vince Gilligan to keep the content accurate on the show.

Watch the video here below, which was produced by the American Chemical Society, and contains clips from Breaking Bad.