Thulium, element number 69, is a hard one to isolate.
Tables charting the chemical elements have been around since the 19th century - but this modern version has a short video about each one. We've done all 118 - but our job's not finished. Now we're updating all the videos with new stories, better samples and bigger experiments. Plus we're making films about other areas of chemistry, latest news and occasional adventures away from the lab.