Thorium, element 90 on the periodic table. Extra footage: https://www.youtube.com/watch?v=UHdhcfVVfZA More radioactive videos: http://bit.ly/radioactive_vids Support us on Patreon: https://www.patreon.com/periodicvideos Featuring Professor Sir Martyn Poliakoff. More chemistry at http://www.periodicvideos.com/ Follow us on Facebook at http://www.facebook.com/periodicvideos And on Twitter at http://twitter.com/periodicvideos From the School of Chemistry at The University of Nottingham: http://bit.ly/NottChem Periodic Videos films are by video journalist Brady Haran: http://www.bradyharan.com/ Brady's Blog: http://www.bradyharanblog.com/ Join Brady's mailing list for updates and extra stuff --- http://eepurl.com/YdjL9